WASH SOLVENT REUSE
IN PAINT PRODUCTION
by
Alice B. Parsons, Kenneth J. Heater, and Robert F. Olfenbuttel
Battelle
Columbus, Ohio 43201
Contract No. 68-CO-0003
Work Assignment No. 3-36
Project Officer
Lisa Brown
Pollution Prevention Research Branch
Risk Reduction Engineering Laboratory
Cincinnati, Ohio 45268
RISK REDUCTION ENGINEERING LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
> Printed on Recydad Papar
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NOTICE
This material has been funded wholly or in part by the U.S. Environmental Protection Agency
(EPA) under Contract No. 68-CO-0003 to Battelle. It has been subjected to the Agency's peer and
administrative review and approved for publication as an EPA document. Approval does not signify
that the contents necessarily reflect the views and policies of the U.S. Environmental Protection
Agency or Battelle; nor does mention of trade names or commercial products constitute recommenda-
tion for use. This document is intended as advisory guidance only to manufacturers of solvent-based
paints in developing approaches to waste reduction. Compliance with environmental and occupational
safety and health laws is the responsibility of each individual business and is not the focus of this
document.
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FOREWORD
Today's rapidly developing and changing technologies and industrial products and practices
frequently carry with them the increased generation of materials that, if improperly dealt with, can
threaten both public health and the environment. The U.S. Environmental Protection Agency (EPA) is
charged by Gongress with protecting the Nation's land, air, and water resources. Under a mandate of
national environmental laws, the agency strives to formulate and implement actions leading to a
compatible balance between human activities and the ability of natural systems to support and nurture
life. These laws direct the EPA to perform research to define our environmental problems, measure the
impacts, and search for solutions.
The Risk Reduction Engineering Laboratory is responsible for planning, implementing, and
managing research, development, and demonstration programs to provide an authoritative, defensible
engineering basis in support of the policies, programs, and regulations of the EPA with respect to
drinking water, wastewater, pesticides, toxic substances, solid and hazardous wastes, Superfund-
related activities, and pollution prevention. This publication is one of the products of that research and
provides a vital communication link between the researcher and the user community.
Passage of the Pollution Prevention Act of 1990 marked a significant change in U.S. policies
concerning the generation of hazardous and nonhazardous wastes. This bill implements the national
objective of pollution prevention by establishing a source reduction program at the EPA and by
assisting States in providing information and technical assistance regarding source reduction. In support
of the emphasis on pollution prevention, the Clean Technology Demonstration (CTD) program has been
designed to identify, evaluate, and/or demonstrate new ideas and technologies that lead to waste
reduction. It continues the efforts of the Waste Reduction Innovative Technology Evaluation (WRITE)
Program. CTD focuses on evaluating and demonstrating technologies available to a particular industry
to minimize pollution at the source. These methods reduce or eliminate transportation, handling,
treatment, and disposal of hazardous materials in the environment. The technology evaluation project
discussed in this report emphasizes the study and development of methods to reduce waste and
prevent pollution.
E. Timothy Oppelt, Director
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
HI
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ABSTRACT
This study evaluates technology for reducing solvent waste by reusing wash solvent in the
manufacture of solvent-borne paint. Solvent used to clean equipment at the end of a production run
is stored for use in subsequent batches of the same or compatible formulations. Three areas were
considered: product quality, pollution prevention, and economics. The benchmark for the evaluation
was solvent-borne alkyd paint manufactured with 100%-new solvent.
The wash-solvent recovery technology as it is practiced at Vanex Color, Inc., Mt. Vernon,
Illinois, produces a product that meets company specifications. Nearly 80% of the wash solvent used
in equipment cleaning is diverted from the wastestream and used in product formulation. On-site
observation, sampling, and laboratory analysis in this study confirm that the physical properties of one
batch of an alkyd house paint manufactured with 80%-wash solvent (mineral spirits) were comparable
to the physical properties of one batch of the same formulation made with 100%-new solvent. The
payback period for this technology was estimated to be about one month, due in part to the low capital
and operating costs. Savings are generated by decreased raw material purchases and reduced volume
of hazardous solvent waste for disposal.
This report was submitted in partial fulfillment of contract Number 68-CO-003, Work
Assignment 3-36, under the sponsorship of the U.S. Environmental Protection Agency. This report
covers the period from November 1992 to September 1993, and work was completed as of January
31, 1994.
IV
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CONTENTS
Page
NOTICE . . ii
FOREWORD
in
ABSTRACT . iv
FIGURE vii
TABLES ." " vii
ACKNOWLEDGMENTS . viii
SECTION 1
PROJECT DESCRIPTION 1
PROJECT OBJECTIVES . ' " ' 1
DESCRIPTION OF THE SITE '.'.'.'.'.'.'. 2
DESCRIPTION OF THE TECHNOLOGY •••••• ^
SUMMARY OF THE APPROACH ...'... '.'.'.'• 5
Product Quality Evaluation 6
Pollution Prevention Potential 6
Estimation of Economics . 6
SECTION 2
PRODUCT QUALITY EVALUATION 7
ON-SITE SAMPLE COLLECTION AND TESTING 7
LABORATORY ANALYSIS AT BATTELLE 10
Grind . . . 19
Gloss 11
Density 1 -\
Percent Solids/Percent Volatiles 12
Viscosity 12
Color 13
PRODUCT QUALITY ASSESSMENT . . . . . . . . .' .' .' . 13
SECTION 3
POLLUTION PREVENTION POTENTIAL -\ 5
WASTE VOLUME REDUCTION 15
WASTE REDUCTION ASSESSMENT ' 17
POLLUTION PREVENTION IMPACT '.'/. 17
SECTION 4
ECONOMIC EVALUATION „ 18
CAPITAL COSTS FOR WASH-SOLVENT REUSE SYSTEM 18
OPERATING COSTS ' i g
ECONOMIC CALCULATIONS '.'.'.'.'.'.'."' 20
ECONOMIC ASSESSMENT ' 20
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CONTENTS (Cont'd)
Page
SECTION 5
QUALITY ASSURANCE 21
FIELD SAMPLING 21
LABORATORY ANALYSIS . . . . 22
COMPANY RECORDS AND INFORMATION FROM INTERVIEWS 24
LIMITATIONS AND QUALIFICATIONS 25
SECTION 6
CONCLUSIONS AND DISCUSSION 26
PRODUCT QUALITY 26
POLLUTION PREVENTION POTENTIAL 27
ECONOMICS 27
DISCUSSION OF IMPACT ' ' '- 27
SECTION 7
REFERENCES . . 30
APPENDIX
RAW DATA FROM LABORATORY ANALYSIS 31
VI
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FIGURE
Paint manufacture schematic/packaging system. ...;.. 4
TABLES
Number
1 SUMMARY OF MEASUREMENTS AND COMPANY HISTORICAL INFORMATION 5
2 SUMMARY TABLE OF FIELD SAMPLES FOR PRODUCT QUALITY ASSESSMENT
AND CRITICAL ANALYTICAL MEASUREMENTS 8
3 RESULTS OF QUALITY-CONTROL TESTS FOR PRODUCT
QUALITY ASSESSMENT PERFORMED AT VANEX 9
4 RESULTS OF TESTS FOR PRODUCT QUALITY ASSESSMENT
PERFORMED AT BATTELLE 10
5. SUMMARY OF PRODUCT QUALITY COMPARING ALKYD HOUSE PAINT
MANUFACTURED WITH 100%-NEW SOLVENT TO ALKYD HOUSE
PAINT MANUFACTURED WITH 80%-WASH SOLVENT 14
6 ANNUAL WASTE REDUCTION THROUGH WASH-SOLVENT
REUSE PROGRAM AT VANEX COLOR, INC 16
7 CAPITAL AND OPERATING COSTS ANALYSIS FOR SOLVENT
REUSE AT VANEX , 19
8 SUMMARY OF QUANTITATIVE QA OBJECTIVES (PRECISION,
COMPLETENESS, AND ACCURACY) FOR CRITICAL MEASUREMENTS 22
9 QUALITY ASSURANCE OBJECTIVES FOR DENSITY DETERMINATION
DATA AT 23°C 24
10 ESTIMATE OF ANNUAL WASTE REDUCTION IF WASH
SOLVENT REUSE IMPLEMENTED THROUGHOUT THE U.S 29
A-1 60° GLOSS READINGS USING HUNTERLAB D48D GLOSSMETER 31
A-2 HEGMAN GRIND 32
A-3 RAW DATA* FOR VISCOSITY AT 25°C 32
A-4 RAW DATA AND CALCULATIONS FOR VANEX ALKYD HOUSE PAINT
PERCENT VOLATILES ASTM D2369 33
A-5 RAW DATA FROM COLOR DIFFERENCE MEASUREMENTS USING CIELAB* 35
A-6 DENSITY DETERMINATION DATA FOR VANEX 2-1 HOUSE PAINT AT 23 "C 35
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ACKNOWLEDGMENTS
Battelle wishes to acknowledge the cooperation and support of Lisa Brown, the EPA Project
Officer, and the technical and administrative staff of Vanex Color, Inc. during the technology evaluation
process. Special thanks to Ken Brandt and Walter Rexing for technical information and production
scheduling that made the program possible.
viii
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SECTION 1
PROJECT DESCRIPTION
This study, conducted by Battelle for the Pollution Prevention Research Branch (PPRB) of the
U.S. Environmental Protection Agency, evaluates a technology for reducing solvent waste by reusing
wash solvent in the manufacture of paint. Solvent used to clean equipment at the end of a production
run is stored for use in the next formulation of the same type of paint.
The Pollution Prevention Research Branch (PPRB) of the U.S. Environmental Protection Agency
is evaluating and demonstrating pollution prevention technologies through the Pollution Prevention
Clean Technology Demonstration (CTD) Program. The goal is to promote the use of clean technologies
that minimize the source of pollution problems in a particular industry. The CTD program is a
continuation of efforts of the Process Engineering Section (PES) of PPRB, which directed the efforts
of the Waste Reduction Innovative Technology Evaluation (WRITE) Program. The CTD program
focuses on the evaluation and demonstration of technologies that can be used within a particular
industry to minimize the source of pollution problems.
To assess this candidate technology for reduction of solvent waste in paint manufacture three
aspects were evaluated: product quality, pollution prevention, and economics. The technology must
produce a quality product and reduce waste or prevent pollution. The economics of the technology
must be quantified and compared with the economics of the existing technology. However, reduction
of operating costs is not an absolute criterion for the use of the prototype technology. There may be
justifications other than saving money that would encourage adoption of new operating approaches.
PROJECT OBJECTIVES
This study evaluates a technology for reducing solvent waste by reusing wash solvent in the
manufacture of paint. Solvent used to clean equipment at the end of a production run is stored for use
in the next formulation of the same type of paint. This study has the following critical objectives:
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• Product Quality: Evaluate the quality of the paint formulated with wash solvent to
ensure that product quality has not been compromised.
• Pollution Prevention Potential: Evaluate the amount of solvent diverted from the
wastestream by this technology.
• Economics: Evaluate the costs and cost savings of this pollution prevention project.
DESCRIPTION OF THE SITE
The site selected for evaluating this technology was Vanex Color, Inc., located in Mt. Vernon,
Illinois. Vanex is a national and international manufacturer of consumer and specialty coatings; its
primary market interests are in the U.S. and Europe. Vanex's primary business and production
operations are staffed by a 32-member team operating out of a 70,000-ft2 manufacturing and
warehouse facility. Annual coatings production volume is approximately 500,000 gal. Vanex focuses
on developing and producing environmentally compatible product lines, including trade sale
architectural paints for interior and exterior surfaces and wood finishing products. Because Vanex
wishes to concentrate on environmentally safe products, the majority (85 to 90%) of the coatings are
based on waterborne technology. However, because some markets continue to rely on solvent-based
formulations, Vanex still produces such products. In the production of solvent-based systems, Vanex
maintains an environmentally conscious stance by following practices it has developed to reduce the
volume of solvent used during manufacture. Wash solvent used to clean production equipment is
categorized and saved. The company reuses wash solvents in the production of subsequent batches
of solvent-based paint formulations.
Solvent reuse technology is one part of a company-wide pollution prevention program instituted
by Vanex to review every wastestream in the office and the production plant with the objective of
minimizing waste. Vanex's strategies include source reduction, raw material substitution, reuse and
recycling of wash solvents where possible, reduction of packaging wastes, recycling of motor oil from
company vehicles, and reuse and recycling of office wastepaper products.
Vanex reports that 80% of all wash solvent generated during solvent-borne paint manufacture
is recycled in house, resulting in an annual cost savings of $15,000. Wash solvent that cannot be
reused (e.g., solvent used to clean equipment after the production of dark custom colors) is shipped
to a fuel blender for use as supplemental fuel in cement kilns.
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DESCRIPTION OF THE TECHNOLOGY
Vanex uses a simple tracking and storage system to handle reuse of the wash solvent. Small
amounts of solvent are used to clean the batch tanks and the dispensing equipment. This solvent is
stored in labeled 55-gal drums for addition back into the same or very similar paint formulations within
90 days.
Only certain coatings are formulated using the stored wash solvents. Product lines selected
for the solvent reuse program were primarily those that could be easily formulated to meet final color
requirements. When these coatings are being formulated, any available wash solvent that can be used
in that particular formulation is blended into the coating formulation during mixing. Fresh solvent is
used for the remaining solvent make-up. The percentage of reused solvent varies from batch to batch,
depending on the amount of stored solvent available at the time of production and the type of paint
being formulated. From 0 to 100% wash solvent may be used.
In the storage area, used solvents are marked as Group 1, Group 2, or Group 3. Mineral spirits
is the primary solvent in solvent-borne coatings produced by Vanex and is the only solvent currently
used in the cleaning process. Group 1 is mineral spirits wash solvent from white, tint, or pastel paint.
Group 2 is mineral spirits wash solvent from clear paint. Group 3 is mineral spirits wash solvent from
gray and light-colored paint. Charts posted for the use of batchmen (formulators) and cleanup workers
list which wash solvent group can be used in the formulation of which paint. The general principal is
that used solvent is added back into the same or very similar formulations. One exception is that of
wash solvent from oil-modified urethanes; it can be used in alkyd formulations, resulting in a tougher
product. The other exception is that no wash solvent is added to the tint bases or pastels because the
titanium dioxide pigment level is critical to later tinting for color matching at the point of sale.
In the past, when Vanex made a variety of colors in the solvent-borne paint and used more
than two solvents, the wash solvent from each formulation was stored separately for reuse. All colors
but white could be added into black batches. The solvent reuse system currently is used for whites,
grays, and clear. Vanex no longer makes enough colored solvent-borne paints such as red, yellows,
or black to justify saving the solvent for reuse. Solvents not selected for reuse are collected in drums,
stored in a waste storage area, and shipped to a solvent blender who processes and sells the mixed
solvent to a cement kiln as a fuel additive.
There is no filtration of the used solvent. During the first 24 hours of storage, pigment settles
out of the wash solvent and collects at the bottom of the drum. When the used solvent is poured from
the storage drums, care is taken to ensure that none of the sediment (mostly pigments) in the bottom
of the drum is added to the formulation. Once the wash solvent has been poured from the drum, the
drum is reused as a wash-solvent storage container until the sediment in the bottom of the drum
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becomes so thick that there is little useable storage space in the drum. At this point, waste solvent
for disposal is added to fill the remainder of the drum, and the drum and its contents are shipped for
disposal. This waste solvent can be generated by equipment cleanup after color batches other than
whites, grays, and clears.
A schematic of the paint manufacturing process is presented in Figure 1, All raw materials are
added to the mixing tank and dispersed using a high-speed dispersion blade that is lowered into the
tank. After all components of the formulation have been added and properly blended, the product is
ready for quality-control testing.
. Mixing Tank (700 gal
capacity)
- Dispersion Blade
Let-down Valve
Vorti-Siv Type
Dispensing Equipment
Outlet VO-1
1-Gallon Paint Cans
.RoD-up Conveyor/Packaging
System
Figure 1. Paint manufacture schematic/packaging system.
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Vanex has a small, efficient on-site laboratory for quality assurance testing, problem solving,
and development of new formulations needed by customers. After mixing, each batch of paint is
tested at 25 °C for viscosity, weight per gallon, gloss, color, and linear flow. Test results are used to
indicate needed adjustments to bring the paint to company specifications. Batches are held for at least
16 hours before final testing and filling.
SUMMARY OF THE APPROACH
The Quality Assurance Project Plan (QAPP), prepared at the beginning of this study, describes
the detailed approach and scientific rationale used to evaluate the reuse of some percentage of wash
solvent to formulate paint (Battelle, 1993). The evaluation covered product quality testing, waste
reduction estimation, and economic analysis. Table 1 summarizes the critical and noncritical
measurements and data collected from company records for this technology assessment.
TABLE 1. SUMMARY OF MEASUREMENTS AND COMPANY HISTORICAL INFORMATION
Objective of '
Evaluation Sample Type
Product Quality Coating samples from
new solvent batch and
wash-solvent batch
wet drawdown test panel
dry film test panel
Pollution Prevention solvent waste
solid waste
solvent-based coatings
solvent purchased
Economics wash-solvent reuse program
Property
viscosity
density
grind
percent solids
wet color
color
gloss
volume disposed
volume disposed
annual production
annual usage
capital costs
operating costs
waste disposal
• costs
Criteria
measurement*
measurement*
measurement*
measurement
measurement*
measurement*
measurement*
company records
company records
company records
company records
company records
company records
company records
Critical
woo Rflftollo
yes — Battelle
yes — Battelle
yes — Battelle
yes — Vanex
no — Battelle
yes — Battelle
yes
no
no
yes
no
no
no
* Vanex and Battelle measurements.
t Battelle measurement.
* Vanex measurement.
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Product Quality Evaluation
The objective of the product quality testing is to determine whether or not the use of retained
wash solvent to formulate subsequent batches of solvent-based coatings affects the quality of the final
product. The paint formulated with wash solvent should meet the product specifications established
by Vanex for the same paint formulated with 100%-new solvent. The evaluation was accomplished
by running the same series of standard analytical tests on a batch of paint formulated with new solvent
and on a batch of paint formulated with 80%-wash solvent. Two batches of a solvent-borne alkyd
house paint were prepared at Vanex, under the observation of the Battelle Laboratory Manager
conducting this study and sampled for laboratory analysis at Battelle as specified in the QAPP.
Pollution Prevention Potential
The second objective of this evaluation is to show that solvent is diverted from the
wastestream by implementation of the solvent reuse program. The pollution prevention potential of
this system is based on the reuse of wash solvent that formerly was disposed of. The use of wash
solvent in the subsequent formulation of coating products would (1) reduce the amount of wash
solvent that must be disposed of as waste and (2) reduce the amount of solvent that must be obtained
for use in the paint formulations* Data were collected from company records and interviews with key
personnel at Vanex.
Estimation of Economics
The objective of the economic estimation is to determine a payback period or cost reduction
associated with the switch to this technology for reducing the solvent wastestream. The economic
analysis included assessing the amount of solvent diverted from the wastestream and the cost
associated with the disposal of the excess waste solvent if it were not reused in subsequent paint
formulations. Data from company records and from interviews with key personnel were the bases for
the economic calculations.
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SECTION 2
PRODUCT QUALITY EVALUATION
Vanex stores mineral spirits used to clean mixing and dispensing equipment after manufacture
of solvent-borne paint and reuses this wash solvent as part or all of the solvent needed in the
manufacture of subsequent batches of paint. Wash solvent is separated carefully into groups based
on colors and material types that have been identified as compatible. The paint formulated with wash
solvent meets the product specifications established by Vanex for the same paint formulated with
100%-new solvent.
Two batches of a proprietary solvent-borne alkyd house paint were prepared at Vanex under
the observation of the Battelle Laboratory Project Manager, and samples were taken to be analyzed
at Battelle. Batch #46481-7 was formulated with 100 gal new mineral spirits and no wash solvent
(0% wash solvent); Batch #46481-4, with 20 gal new mineral spirits and 80 gal wash solvent (80%
wash solvent).
Samples of each batch were collected for laboratory analysis. The same series of standard
analytical tests was run on both batches. If the measured properties of the batch manufactured with
80%-wash solvent closely match the measured properties of the batch manufactured with 100%-new
solvent, the product quality objective will be met.
ON-SITE SAMPLE COLLECTION AND TESTING
Four 2-qt field samples (Table 2) from each coating batch were collected from the Vorti-Siv
outlet at point VO-1 (shown in Figure 1). These samples, representative of Vanex's final commercial
product, were collected in the retail gallon paint cans that are used to package and ship to the
purchaser. For each batch, one sample was collected at the beginning of the dispensing process (4-1
and 7-1), two samples in the middle of the dispensing process (4-2, 4-3, 7-2, and 7-3), and one sample
at the end of the process (4-4, and 7-4). Sample size was approximate. Samples were assigned
sample ID numbers and labeled as defined in the QAPP.
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TABLE 2. SUMMARY TABLE OF FIELD SAMPLES FOR PRODUCT QUALITY
ASSESSMENT AND CRITICAL ANALYTICAL MEASUREMENTS
Field Sample Type
Number of Field Samples
Field Sample
Number*
Product Quality:
1) batch formulated with 100%- 4 (2 qt each)f
new solvent
2) batch formulated with 80% 4 (2 qt each)'
wash solvent
3) Wet film sample — side-by-side 1 panel for each coating
drawdown of formulation batch evaluated
batch with color standard
7-1
7-2
7-3
7-4
4-1
4-2
4-3
4-4
4 drawdown
7 drawdown
* The 46481- prefix for the Battelle designation for this study is omitted in test
references to samples.
t Three 2-qt samples were tested. Samples 4-3 and 7-3 were held in reserve.
Samples were evaluated in the field by Vanex using the test methods listed in Table 3. These
are standard tests used in the coatings industry as described in ASTM D2932-80 (reapproved in 1988).
Descriptions of the properties and test methods selected for this evaluation were included in the QAPP.
Testing at Vanex was performed by Vanex quality assurance personnel. Vanex performs these
tests after the initial formulation and after a 16- to 24-hour holding period prior to dispensing into
containers. If adjustments to the formulation are made to bring a parameter into a specified range, the
tests are repeated after each adjustment to verify that the quality of the coating meets criteria for
packaging and shipping.
The results of the product quality analyses are shown in Table 3. The paint formulated with
80%-wash solvent compared well to the paint formulated with 100%-new solvent. Table 3 contains
the Vanex quality-control test results for both batches of coatings. Except for the grind determination,
these tests were completed more than 16 hours after formulation and just before paint was dispensed
into consumer cans. The paint made with wash solvent required no adjustments to meet the expected
ranges. The paint formulated with 100%-new solvent required the addition of 2 gal of mineral spirits
to bring the final viscosity from 91 Krebs units to 89 units.
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TABLE 3. RESULTS OF QUALITY-CONTROL TESTS FOR PRODUCT
QUALITY ASSESSMENT PERFORMED AT VANEX
Property (Units)
Viscosity (Krebs Units)
Density (Ib/gal)
(g/ml)
Grind (Hegman Scale)
Linear Flow (sag)
Color
Gloss (gloss units)
Test Method*
ASTM D562-81 (reapproved
1 990)
ASTM D1 475-90
ASTM D1 21 0-79 (reapproved
1988)
ASTM D4400-89a
Visual comparison with stored
standard
ASTM D523-89 (60°)
Vanex
RangeT
88±2
10.36 ±0.05
(1 .24.+. 0.0)
>5
12
Match stored
standard
>80
New-Solvent
Batch
89
10.37
(1,24)
6 +
12
yes
87.1
Wash-Solvent
Batch
89
10.40
(1.25)
5 +
12
yes
86.6
* American Society for Testing and Materials, 1992 Annual Book of ASTM Standards, Vol. 06.01,
"Paint — Tests for Formulated Products and Applied Coatings".
t Approved range for Vanex #2-1 alkyd housepaint.
According to Vanex personnel, there has been no noticeable increase in the frequency with
which adjustments are needed to bring batches manufactured with wash solvent into specifications.
The field experience supports this claim in a limited way. The coating batch manufactured with new
solvent required one adjustment to bring viscosity into the specified range. The coating batch
manufactured with wash solvent required no adjustment.
The "fineness of grind" determination (ASTM 1210) is performed at the end of the pigment
dispersion step prior to letdown. For satisfactory pigment dispersions, Vanex wants the grind at this
point to be at least a "5" on the Hegman scale. The new solvent batch was rated as a "6 + " and the
wash-solvent batch, a "5 + " on the Hegman scale.
The critical color measurement for the paint batches being evaluated was the visual match of
wet color by the Vanex quality-control staff. For each of its product lines, Vanex maintains a stock
of sample coatings that are used as color standards. The color of the coating being formulated is
checked against these coatings by performing a visual comparison on a wet side-by-side drawdown
of the batch and the appropriate color standard. Any color deviations noted are corrected for by
additions of small amounts of tint, until a match with the standard is obtained. The Vanex quality-
control staff judged the wet color of both batches matched the wet color of the standard without
adjustment.
The other quality-control tests performed by Vanex and listed in Table 3 were not selected as
"critical measurements" for comparison of the paint batches in this technology evaluation. However,
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these data for the two batches indicate a close match for the tested parameters. Vanex rated these
two batches of alkyd house paint as comparable in quality. The batches were dispensed into cans for
shipment to customers.
LABORATORY ANALYSIS AT BATTELLE
Table 4 lists the results of the Battelle laboratory analysis of the field samples collected during
the site visit. Raw data for each test are included in the appendix to this report. Quality assurance
data are found in Section 5, "Quality Assurance."
TABLE 4. RESULTS OF TESTS FOR PRODUCT QUALITY ASSESSMENT
PERFORMED AT BATTELLE
Property (Units)
Test Method*
New Solvent Batch Wash-Solvent Batch
Viscosity (Centipoises)
Density (Ib/gal)
Grind (Hegman Scale)
Percent Solids (%)
Percent Volatiles {%)
Color (A E) CIELAB
Gloss (gloss units)
ASTM D2196-86 (reapproved 1991)
ASTM D1475-90
ASTM D1210-79 {reapproved 1988)
ASTM D23 69-90
ASTM D2369-90
ASTM D2244-89
ASTM D523-89
4000
data not valid
8
73.4
26.6
Standard for comparison
79.4
4000
data not valid
8
73.5
26.5
0.2
81.6
* American Society for Testing and Materials, 1992 Annual Book of ASTM Standards, Vol. 06 01
"Paint — Tests for Formulated Products and Applied Coatings".
Grind
Grind was assessed using standard equipment and methods outlined in ASTM D1210-79
(reapproved 1988): "Standard Test Method for Fineness of Dispersion of Pigment Vehicle Systems."
Macroscopic solid contaminant or poorly dispersed (agglomerated) solids would affect the grind results.
Results for the "fineness of grind" analysis on the final coatings are the same for both the new
solvent and wash-solvent batches at 8 Hegman units. Both coatings had a uniform dispersion of
particles with no evidence of agglomeration or gross solid particulate contamination. There was no
discernible difference in test performance between the paint manufactured with new solvent and the
10
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paint manufactured with wash solvent. Battelle results (8 Hegman units) indicate a slightly finer grind
than do the Vanex test results (5+ and 6+ Hegman units). However, the tests at Vanex directly
followed the pigment dispersion step while Battelle tests were made on the final formulated coating.
Gloss
Gloss measurements were made on dry film on a HunterLab Glossmeter in accordance with
ASTM D523-89: "Standard Test for Specular Gloss" and the QAPP. Gloss measurements are a gauge
of the appearance of the coating as it is applied to a substrate. The experimental gloss determinations
made at Battelle for the two batches are statistically different from each other at the 95%-confidence
level based on the nine data points determined for each. Based on ASTM variation allowable at the
95%-confidence level for reproducibility between laboratories, results for gloss could have been 80 .±
3.5 (76.5 to 83.5) gloss units. Gloss for the wash-solvent batch had a mean of 81.6, meeting Vanex's
specification that the gloss of alkyd house paint be greater than 80. Gloss for the batch formulated
with 100%-new solvent had a mean of 79.4, or 0.6 of a gloss unit below the Vanex target. Both of
these gloss averages fall within the 3.5 gloss units variation allowed at the 95%-confidence level for
reproducibility between laboratories.
The critical objective for gloss in this evaluation is that the gloss of the batch formulated with
wash solvent should be as good as the gloss of the new-solvent batch. For this paint, Vanex considers
a higher gloss more desirable than a gloss lower than 80. In testing at Battelle, the gloss of the wash-
solvent batch tested slightly higher than that of the new-solvent batch but not statistically different.
At Vanex the new-solvent batch had a slightly higher gloss than the wash-solvent batch but
not statistically different. The variation between the gloss measurements at Vanex and those at
Battelle could be attributable to the use of different instruments for gloss measurement in the two
laboratories. In both tests, the new-solvent batch and the wash-solvent batch had gloss measurements
that met or exceeded Vanex product specifications for this paint formulation.
Density
Density measurements were performed in accordance with ASTM D1475-90: "Standard Test
Method for Density of Paint, Varnish, Lacquer, and Related Products." The density of the coating was
measured to compare the consistency of the two paint sample batches. Agreement of density
measurement can indicate that the solid and liquid components of the coating formulation were added
in the correct proportions.
11
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Density data measured at Battelle for the field samples were not considered valid for comparing
product quality. A detailed explanation can be found in Section 5, "Quality Assurance," where QA for
the data is summarized in Table 9. Data collected for replicates from the same field sample met the
requirements for the 95%-confidence limit. However, the means of the density data for multiple field
samples of the same sample coating batch did not meet the requirements for the 95%-confidence
level. During Vanex quality-control tests, the density determination represented one sample per batch,
rather than multiple samples taken at different times from the same batch. There is no background
data for comparison. The testing specified in the QAPP for this evaluation was more rigorous than
standard industry practice. The determinations of density were inconclusive for meeting the product
quality objective.
Percent Solids/Percent Volatiles
Percent solids/percent volatiles was determined according to ASTM D2369-90: "Standard Test
Method for Volatile Content of Coatings." The percent-solids (nonvolatile) content was determined
by subtracting the percent-volatiles content from 100%. In paint manufacture, this test is used for
one check of the solvent level in a paint. It is important for proper viscosity and film formation that
the solvent level be consistent. This measurement was used in this evaluation as a basis for
determining whether solid contaminant materials are introduced into the formulation when the wash
solvent is used.
Determinations were made on replicate samples from three field samples collected for each
coatings batch. The test was repeated on two separate days by the same technician. The average
percent solids for the coating batch manufactured with new solvent was 26.6%; the percent volatiles,
73.4%. The average percent solids for the coating batch manufactured with wash solvent was
26.5%; the percent volatiles, 73.5%. There is no statistical difference between these batches of
coatings based on determination of the percent solids/percent volatiles. Based on percent
solids/percent volatiles determination, the use of wash solvent did not affect the solids and volatiles
content of the paint formulated.
Viscosity
The measurement of viscosity was performed in accordance with ASTM D2196-86: "Standard
Test Method for Rheological Properties of Non-Newtonian Materials by Rotational (Brookfield)
Viscometer." Although this is not the viscosity test used routinely at Vanex, it is a widely accepted
test method for evaluating viscosity in the coatings industry. Viscosity is a critical property for
12
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coatings. The viscosity of the coating impacts the paint application methods and the thickness at
which the coating can be applied without running or sagging.
The average viscosity for the new-solvent batch measured 4000 centipoises. For the wash-
solvent batch, the average viscosity measured 4000. These viscosities are not statistically different
at the 95%-confidence level for this test. Based on the viscosity determination, no difference was
found between the coatings batch manufactured with wash solvent and the coatings batch formulated
with new solvent.
Color
Battelle performed a "noncriticar instrumental measurement of dry film color in accordance
with ASTM D2244-89: "Standard Test Method for Calculation of Color Differences From
Instrumentally Measured Color Coordinates." A MacBeth 2000 Color Analyzer was used to provide
quantitative background information on color difference. Because Vanex does not use instrumental
color analysis routinely, no data are available to establish the range of results for color differences that
might be acceptable for this particular alkyd paint from batch to batch. However, in practice, a color
difference of less than 0.5 is considered below the limits of detection. A color difference of 1.0 or less
is considered a commercial match.
The results of the instrumental analysis are shown in Table 4 as color difference calculated by
the CIELAB formula. When the batch manufactured with wash solvent was compared to the batch
manufactured with new solvent, the color difference was 0.2. Therefore, the instrumental analysis
of color indicated no significant difference in color between the batch made with 100%-new solvent
and the batch made with 80%-wash solvent. This agrees with the results of the Vanex wet color
determination. This color measurement test was not "critical" to the determination of product quality
in this evaluation.
PRODUCT QUALITY ASSESSMENT
The alkyd house paint formulated with 80%-wash solvent meets or exceeds Vanex's
specifications for this product in terms of grind, viscosity, linear flow, wet color, and gloss. The
product satisfies the quality-control standards at Vanex. Paint manufactured with some percentage
of wash solvent has been sold by Vanex for several years with no indication of unsatisfactory
appearance or performance in the field.
13
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Results of the critical measurements for the product quality analysis in this evaluation are
summarized in Table 5. Data from density determinations are not included because data did not meet
all the quality-control objectives. No decrease in quality was evident from the laboratory analysis of
the field samples of this alkyd house paint. The batch manufactured with 80%-wash solvent compared
very well with the batch manufactured with 100%-new solvent. Although the sampling and analysis
were limited to two batches, these samples did represent the extremes of wash-solvent use for this
formulation. In other formulations, Vanex has completely replaced the new solvent with wash solvent.
However, in the alkyd formulation sampled, 20 gal of new solvent is required to dilute, or cut, the long
oil alkyd for better mixing. If wash solvent is used for the cutting, the long oil alkyd is sometimes
agglomerated and will not disperse in the paint-mixing process.
TABLE 5. SUMMARY OF PRODUCT QUALITY COMPARING ALKYD HOUSE PAINT
MANUFACTURED WITH 100%-NEW SOLVENT TO ALKYD HOUSE
PAINT MANUFACTURED WITH 80%-WASH SOLVENT
Property
Wash-solvent Batch Compared with New-solvent batch is
Viscosity
Grind
Percent solids/percent volatiles
Wet Color
Gloss
Density
not significantly different
the same
not significantly different
the same
not significantly different
inconclusive
Although the sample size (two batches) was limited, the quality-control tests at Vanex and the
laboratory analysis at Battelle indicate that the quality of this solvent-borne alkyd house paint made
with wash solvent is comparable to the product quality of the same paint made with 100%-new
solvent. These results compare well with the experience that Vanex has accumulated during several
years use of this wash-solvent recovery system.
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SECTION 3
POLLUTION PREVENTION POTENTIAL
The pollution prevention potential of this system is based on the reuse of wash solvent that
formerly was disposed of. The use of wash solvent in the subsequent formulation of coating products
would (1) reduce the amount of wash solvent that must be disposed of as waste and (2) reduce the
amount of solvent that must be purchased for use in the paint formulations. Interim storage for reuse
must not contribute to pollution. Information from company records and from interviews with key staff
was gathered to determine the volume of mineral spirits diverted from the wastestream by
implementation of the reuse program at Vanex.
WASTE VOLUME REDUCTION
A major source of solvent waste in the manufacture of solvent-borne paint is the solvent
required to clean the mixing and dispensing equipment between batches. Employees at Vanex make
a conscious effort to minimize the amount of solvent required for cleaning by techniques such as
scraping the mix tanks to remove many paint solids before solvent cleaning. Workers minimize cleanup
of work areas and equipment by taking care when adding raw materials and dispensing finished
batches. When possible, they arrange production schedules so that similar batches of paint are mixed
and dispensed one after another to eliminate cleanup between batches.
From 15 to 20 gal of solvent are required to clean equipment between batches. This wash
solvent is labeled and stored in 55-gal drums for addition back into the same or very similar paint
formulations within 90 days. At Vanex, 80% of the wash solvent is reused in paint formulation. Wash
solvent that cannot be reused is shipped to a fuel blender for use as supplemental fuel in cement kilns.
(Note: Depending on the formulations involved, other operations could reuse more than 80% of their
wash solvent.)
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Calculations based on 1992 production figures and background information collected during
the two site visits to Vanex (Table 6) demonstrate two areas of waste reduction potential of this
technology as it is practiced at Vanex for manufacture of solvent-borne paints:
• Solvent waste for disposal was reduced from 75 drums to 15 drums.
• Volume of mineral spirits purchased for paint manufacture was reduced by nearly 16%.
TABLE 6. ANNUAL WASTE REDUCTION THROUGH WASH-SOLVENT
REUSE PROGRAM AT VANEX COLOR. INC.
Vanex Production Data:
Production in 1992 of solvent-borne paints: 82,500 gal (312,000 L)
Average batch size 400 gal (1,500 L)
Estimated number of batches/year: 206 batches
Quantity of mineral spirits used to clean 20 gal (75 L)
tanks and equipment between batches:
Wash Solvent Calculations:
Without Reuse
Solvent required for cleanup only 4,120 gal (15,600 L)
(206 batches X 20 gal/batch)
Wash solvent disposed 4,120 gal (15,600 L)
With Reuse
Solvent required for cleaning only 4,120 gal (15,600 L)
(206 batches X 20 gal/batch)
Solvent reused for formulation 3,300 gal (12 500 L)
(80% X 4,120 gal)
Wash solvent disposed 820 gal (3,100 L)
Waste Reduction 3,300 gal (12,500 L)
It should be noted that the 15-drum figure for waste disposal does not include solid waste from
tank scrapings or disposal of off-specification paints. The volume of these wastes is not affected by
the solvent reuse system. Also, the ratio of 100 gal mineral spirits per 400 gal solvent-borne paint
produced is based on the formulation of the alkyd house paint tested in this evaluation. Vanex makes
other proprietary solvent-borne formulations that could have slightly higher or lower mineral spirits
content. The percentage of mineral spirits in other solvent-borne formulations and the production
volume of each type is proprietary.
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WASTE REDUCTION ASSESSMENT
Vanex uses a simple storage and tracking system to divert 3,300 gal of mineral spirits {60
drums per year) from the wastestream to product formulation, This represented an 80% reduction in
mineral spirits disposed of as waste in 1992. This reduction occurred with little change to the paint
production process at Vanex. The volume diverted from the wastestream could vary from year to year,
depending oh the product mix and the annual production. However, this low-tech system has
produced an appreciable reduction in solvent waste at Vanex.
POLLUTION PREVENTION IMPACT
Interim storage of wash solvent for reuse at Vanex does not create an additional source of
pollution. Wash solvent is stored in closed barrels in the same way that waste solvent is stored to
await disposal. The maximum storage on site for any waste is 90 days. Wash-solvent recovery
storage drums are dated; solvent that is not reused for paint manufacture in less than 90 days is
disposed of as waste solvent with the normal waste pickup. Vanex plans production schedules so as
to avoid disposal of any reusable wash solvent. Waste solvent from the manufacture of solvent-based
paint at Vanex is hazardous waste because of its flash point. All paint-manufacturing waste is handled
and disposed of by Vanex in accordance with the applicable local, state, and federal regulations. The
wash-solvent recovery system does not generate any additional waste at Vanex.
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SECTION 4
ECONOMIC EVALUATION
The objective of the economic estimation is to calculate a payback period and/or cost reduction
associated with implementation of this technology for reducing the solvent wastestream. Economic
estimations for evaluating the technology are based on capital and operating costs.
CAPITAL COSTS FOR WASH-SOLVENT REUSE SYSTEM
The wash-solvent reuse system used by Vanex did not have significant capital costs. No
equipment was purchased, no additional storage area was needed, and no additional energy- or air-
supply systems were required. Total expenditure to implement the system is estimated by Vanex
personnel to be less than $1,000 for both materials and labor.
The Vanex technical staff put together the master list of wash solvents and paints that could
be formulated with the wash solvents, based on the chemistry of the polymers, the color of the
pigments, and the gloss required in the paint being mixed. Initially, wash solvents stored for reuse
were assigned to one of six mixing groups called solvent-recovery groups. A copy of the master list
was posted on a clipboard for ready access in the storage area. The solvent-recovery groups now are
down to three due to decreased production of solvent-borne paint at Vanex.
A storage area was marked off with paint stripes on the floor to create sections for each
designated wash-solvent group. Fifty-five-gal drums that had held purchased raw materials were
cleaned and labeled for holding stored solvent. Periodically, as the solids build up in the bottom of a
storage drum, the drum is used for disposal of waste solvent and a replacement drum is labeled For
holding and storage of useable wash solvent. Labeling of the drums and storage area was accom-
plished by the regular maintenance staff. Therefore, capital costs for implementation of the wash-
solvent reuse system at Vanex were negligible.
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OPERATING COSTS
The major operating costs associated with the wash-solvent reuse system are given below
(Table 7). Vanex has seen no change in labor costs for paint formulation. Labor costs are the same
whether wash solvent is disposed of or stored for reuse. The wash solvent must be collected in drums
in both cases. Labor for adding the wash solvent to the paint formulation is not a significant added
cost to the mixing operation. At Vanex, addition of raw materials to the mix tank is partly by hand
from drums or bags. New solvent is available by pump from bulk storage tanks, but Vanex employees
report that addition of one or more drums of stored wash solvent is not time-consuming. No additional
electricity is required. Drums are lifted to the raised mixing platform by forklift along with other raw
materials such as bags of dried pigment.
TABLE 7. CAPITAL AND OPERATING COSTS ANALYSIS FOR
SOLVENT REUSE AT VANEX
Vanex's Capital Cost:
Total estimated costs for labor and signage materials
$1,000
Comparison of Vanex's Ooeratina Costs*
Without
Solvent
Reuse
With 80%
Solvent
Reuse
Cost Item
Solvent for cleaning only
Solvent waste disposal
Total Without Reuse
Solvent not reused
Solvent waste disposal
Total With Reuse
Annual savings with reuse
Annual Amount
4, 120 gal
75 drumst
820 gal
15 drumst
of 80% of wash
Unit Cost
$0.79/gal
$150/drum
$0.79/gal
$150/drum
solvent:
Annual Cost
$ 3,250
$11,250
$14,500
$ 650
$ 2,250
$ 2,900
$11.600
* Electricity, maintenance, labor are the same for both cases.
t Fifty-five-gal drums.
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ECONOMIC CALCULATIONS
A simple payback period calculation for this technology evaluation can be performed with the
capital and operating costs. The cost savings in this system come from the reduction of disposal
charges and the reduction of solvent purchases.
Payback = capital costs
savings in annual operating costs
Capital costs at Vanex, including materials and labor, to implement the wash-solvent recovery
system were less than $1,000.
Total operating savings are $11,600; this includes savings on both waste disposal and raw
material purchases based on 1992 figures. Operating costs are affected also by reducing the volume
of new solvent purchased. Because solvent prices fluctuate with the market and the volume
purchased, these savings vary somewhat.
Disposal for hazardous waste in drums costs about $150/drum, or $ 11,250 for disposal of the
75 drums of wash solvent annually if no solvent is reused. Cost for disposing of the 15 drums after
implementation is $2,250 for an annual savings of $9,000. Waste disposal costs differ geographically
and probably will continue to rise.
The recovery of 3,300 gal of wash solvent for use in paint manufacture reduces solvent raw
material purchase by that amount. Based on a cost of $.79 per gal for mineral spirits, this represents
a savings of about $2,600.
ECONOMIC ASSESSMENT
The payback period for implementation of the wash-solvent recovery system at Vanex was
approximately one month. Savings for other companies instituting similar systems will vary with
production volumes and the volume of wash solvent recovered from the wastestream.
Payback = $1,000
$11,600
Payback ^_one month
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SECTION 5
QUALITY ASSURANCE
A Quality Assurance Project Plan (Battelle, 1993) was prepared and approved by the EPA
before testing began. This plan outlined a detailed design for conducting this technology evaluation,
including parameters for field sampling, laboratory analysis, and data reduction. The quality assurance
objectives included in this QAPP are discussed below.
FIELD SAMPLING
Two batches of a solvent-borne paint were manufactured at Vanex under the observation of
the Battelle Laboratory Project Manager as detailed in the QAPP. The formulation was the same for
both batches, but one was made with 100%-new solvent (mineral spirits) and the other with 80%-
wash solvent.
Field samples were collected during the regular dispensing step in accordance with the QAPP.
All samples were collected in a manner that would make them representative of the coatings batch
being manufactured. Samples were taken at different times during the letdown of the coatings to
increase the random nature of the sampling. The laboratory manager labeled, sealed, and documented
each sample description and sample identification number.
Representativeness is the degree to which a sample or group of samples is indicative of the
population being studied. Representativeness normally is achieved by collecting a sufficiently large
number of unbiased samples. The field samples collected in this technology evaluation comprise a
small sample of the range of products manufactured by Vanex using some percentage of wash solvent
in place of new solvent. The ratio of wash solvent to new solvent varies in production from one batch
to the next. The conclusions about product quality in this evaluation have been confined to
conclusions that can be drawn from this limited sample. However, the two coatings batches
manufactured for this evaluation represent the extremes of wash solvent use for this alkyd house paint
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— one batch had no wash solvent and the other had the maximum 80%-wash solvent. If differences
in quality are detectable, the comparison of these two sample batches should reveal them.
Two deviations from the planned field sampling procedure occurred and were approved by the
Battelle Study Leader. First, field samples were collected in the 1-gal consumer paint cans regularly
used by Vanex rather than in the sampling containers specified in the QAPP. This change allowed
sampling to be less intrusive in the dispensing operation and helped meet safety precautions for
shipping. Second, samples of approximately 2 qt each were collected, instead of the 1-L samples
planned in the QAPP. The planned quality-control tests were performed by Vanex staff, and both
batches of paint met Vanex's specifications for this type of solvent-borne paint.
LABORATORY ANALYSIS
All analyses were performed as proposed in the QAPP. Table 8 summarizes the achievement
of the QA objectives for the critical measurements. More detailed information on the 95%-confidence
levels for each ASTM Test Method is included in the appendix with each tabulation of raw data.
TABLE 8. SUMMARY OF QUANTITATIVE QA OBJECTIVES (PRECISION, COMPLETENESS,
AND ACCURACY) FOR CRITICAL MEASUREMENTS
Test Property
(units)
ASTM D21 96-86
Viscosity
(centipoises)
ASTM D1 475-90
Density (grams/gal)
ASTM D1 210-79
Grind
(Hegman Units)
ASTM D2369-90
Percent Solids/
Percent Volatiles
(%)
Vanex Procedure
Wet Color Match
ASTM D523-S9
Gloss
(gloss units)
Number of
Determinations
(9) — 3 replicate tests on each
of 3 wet samples from each
formulation
(9) — 3 replicate tests on each
of 3 wet samples from each
formulation
(9) — 3 replicate tests on each
of 3 wet samples from each
formulation
(9) — 3 replicate tests on each
of 3 wet samples from each
formulation
1 for each batch evaluated
(9) — 3 replicate tests on each
of 3 samples (dry films) from
each formulation
Precision*
Yes — results differ
by less than
9.5%.
No — results differ
by more than
0.6%.
Yes — results differ
by less than 1
Hegman unit.
Yes — results differ
by less than 1 .5%
except for one
measurement1.
Not applicable.
Yes — results differ
less than two
gloss units.
Completeness
Goal =80%
Actual = 100%
Goal =80%
Actual = Invalid
Goal = 80%
Actual = 100%
Goal =80%
Actual = 94%
100%
Goal =80%
Actual = 100%
Accuracy
Yes — viscosity determined for
standard oil was ± 5% of stated
viscosity.
Yes-— density determined for
distilled water is ±0.6% of the
known density of distilled water
at 23 'C.
Yes — sample results compared
to graphic standards using
calibrated gage.
Yes — sample compared to sam-
ple with known solids content.
Not applicable.
Yes — no drift of calibrated tile
measurements.
* 95%-confidence level as defined by the ASTM Test Method.
t One measurement flagged as suspect.
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Analytical data for grind, viscosity, color, and gloss were judged valid. One data point was
flagged as invalid in the percent-solids/percent-volatiles analysis. This data differed more than the
1.5% specified at the 95%-confidence level for this ASTM Test Method (See Table A-4 in the
appendix). The mean for this determination was calculated both with and without the suspect data
point, and both results were statistically the same. The Battelle Study Leader decided to flag the
suspect data point as invalid. The completeness goal for this analysis was 80%. Including the one
invalid data point, 94% completeness was obtained.
The density data for the samples met 0.6% variation at the 95%-confidence limit for the
replicate measurements within each field sample. However, the mean densities of samples 4-1, 4-2,
and 4-4 (samples from the same coatings batch) differ by more than the 0.6% variation that is
acceptable for samples that represent the same population. The same is true for samples 7-1, 7-2,
and 7-4. The variation between the means of the field samples is greater than the 0.6% acceptable
at the 95%-confidence level. The control determination of the density of distilled water run with these
samples was within 0.6% of the known density of distilled water at 23 * C. The density determination
was repeated with similar results. Therefore, the raw data as recorded (Table A-6 in the appendix) do
not meet the quality assurance standards specified in the QAPP.
The internal consistency of the measurements for each field sample and for the control sample
of distilled water indicate that the test procedure was performed accurately. However, the densities
of the field samples collected at different points in the dispensing process appear to vary more than
is allowable for identical samples tested in the same laboratory by the same operator. The determined
density values suggest that the field samples varied somewhat in density. It should be noted that this
sampling and testing matrix is more rigorous than routine quality-control testing used in the coatings
industry. In industry testing, one sample from large batches (>400 gal) is checked for density, not
multiple samples from different areas of the tank. The test plan in the QAPP for this coatings
parameter may require a higher standard than is used in the coatings industry.
The density data do not meet the quality assurance objectives defined in the QAPP. The data
and the objectives are summarized in Table 9. The Battelle Quality Assurance Officer, the Battelle
Study Leader, and the Laboratory Project Manager determined that analysis of the reserve samples
likely would not alter these results.
Viscosity, grind, and gloss test results for each batch are reported as the mean of nine
determinations. Percent-solids/percent-volatiles test results are reported as the mean of 18 determina-
tions for the wash-solvent batch and 17 determinations for the new-solvent batch (one data point
flagged). Wet color, the critical color determination for this evaluation, is based on a visual
examination of side-by-side drawdowns of the batch being tested and a stored color sample of like
paint.
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TABLE 9. QUALITY ASSURANCE OBJECTIVES FOR DENSITY DETERMINATION DATA AT 23 "C
Sample it
W
Density, Ib/gal
Within Sample Set
Between Field
Samples
Wash Solvent
4648 1-4-1 -A
46481 -4- 1-B
46481 -4- 1-C
46481-4-2-A
46481-4-2-B
46481-4-2-C
46481-4-4-A
46481-4-4-B
46481-4-4-C
241.05
241.06
241.05
241.78
241.77
241.73
241.60
241.61
241.60
10.23
10.23
10.23
10.31
10.30
10.30
10.28
10.28
10.28
Valid*
Valid*
Valid*
In valid *
New Solvent
4648 1-7-1 -A
4648 1-7- 1-B
4648 1-7- 1-C
46481-7-2-A
46481-7-2-B
46481-7-2-C
46481-7-4-A
46481-7-4-B
46481-7-4-C
Distilled Water
Distilled Water
Distilled Water
241.59
241.60
241.60
239.52
239.57
239.55
242.41
242.60
242.48
221.99
222.00
222.00
10.28
10.28
10.28
10.08
10.08
10.08
10.36
10.38
10.38
8.32 at 23'C
8.33 at23°C
8.33 at23°C
Valid*
Valid*
Valid*
Valid
Invalid1
Valid compared
to known densi-
ty
* Results valid at 95%-confidence level if difference is less than 0.6%.
t Results (mean of multiple determinations) are valid at 95%-confidence level if
difference is less than 0.6%.
COMPANY RECORDS AND INFORMATION FROM INTERVIEWS
The representativeness of pollution prevention potential data and economic data from company
historical records is as good as possible, given the sources available to the project team. Calculations
are based on 1992 data provided by Vanex. However, assumptions were made to work around
proprietary information {e.g., product formulations, business sensitive records, raw material prices).
At the request of Vanex, actual copies of company records were not collected. The Battelle Study
24
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Leader chose representative data for the longest time period available. The data collected are
documented in the Laboratory Record Book and in this final report.
LIMITATIONS AND QUALIFICATIONS
Given the QA assessment cited above, results of the field collection of samples, the data
collected from company records, and the laboratory testing can be considered valid bases for drawing
conclusions about the product quality, pollution prevention potential, and economics of this wash-
solvent reuse system. Density data differ more than 0.6% (95%-confidence level) from one field
sample to the next for the same coatings batch. Therefore, density data are considered invalid for
comparing product quality. The calculations of waste reduction and of economics are based on certain
assumptions about coatings formula and batch size. Assumptions made for the calculations are
identified in the text and figures so that readers can simulate specific paint-manufacturing scenarios
for their own products and processes.
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SECTION 6
CONCLUSIONS AND DISCUSSION
Vanex Color has instituted an aggressive pollution prevention program that has been recognized
by the National Paint and Coatings Association as one of the most effective in the coatings-
manufacturing industry {Greenfield, 1993; O'Neill, 1992). One element of this pollution prevention
program is reducing solvent waste by reusing wash solvent to cleanup equipment between batches
of paint. In the past, this cleaning solvent was disposed of as waste.
On-site evaluation of the wash-solvent recovery system included product quality, pollution
prevention potential, and economics. Wash solvent is the primary source of solvent waste in the paint
manufacturing process. While a number of companies now are using variations of this concept, there
has not been a rigorous analysis of the environmental or economic impacts.
PRODUCT QUALITY
The objective of the product quality testing was to determine whether or not use of retained
wash solvent in the formulation of subsequent batches of solvent-based coatings affected the quality
of the final product. Two batches of a solvent-borne alkyd house paint were prepared at Vanex under
the observation of the Battelle Laboratory Project Manager and sampled for laboratory analysis at
Battelle. One batch was made with 100%-new solvent; the other, with 80%-wash solvent. The same
series of standard analytical tests was run on representative samples of each batch.
Although the sample size (two batches) was small, the quality-control tests at Vanex and the
laboratory analyses at Battelle indicate that the product quality of this solvent-borne alkyd house paint
made with recovered wash solvent is comparable to that of the same paint made with 100%-new
solvent. These results compare well with the experience that Vanex has accumulated while using this
wash-solvent recovery system for several years in a variety of paint formulations. Every batch of paint
formulated at Vanex must meet company QA standards established for that paint type.
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POLLUTION PREVENTION POTENTIAL
The pollution prevention potential of this system is related to the reuse of wash solvent that
formerly entered the wastestream. The reuse of wash solvent in the subsequent formulation of coating
products (1) reduces the amount of wash solvent that must be disposed of as waste and (2) reduces
the amount of solvent that must be purchased for use in the paint formulations. Interim storage of the
wash solvent prior to reuse does not contribute to additional pollution, Vanex is able to reuse about
3,300 gal of mineral-spirits wash solvent per year.
ECONOMICS
The payback period for implementation of the wash-solvent recovery system at Vanex was
about one month. Vanex has estimated yearly savings through the wash solvent recovery system at
$15,000. The conservative estimate, based on figures from 1992, that resulted from Battelle's
calculations in this technology evaluation was $11,600 per year . Capital costs in the first year were
estimated at less than $1,000.
Savings for other companies instituting similar systems will vary with production volumes and
volumes of wash solvent recovered from the wastestream. Waste disposal costs probably will
continue to rise. Operating costs are reduced by reducing the volume of new solvent purchased.
Solvent prices fluctuate with the market and the volume purchased. Therefore, these savings vary
somewhat.
DISCUSSION OF IMPACT
The major source of solvent waste in paint manufacture is wash solvent used to clean tanks
and equipment. The very simplicity of this technology makes it desirable for paint companies actively
pursuing reduction of solvent waste. It is especially useful for small-to-medium companies
manufacturing several solvent-borne paints in small production batches.
The wash-solvent recovery system can be used by manufacturers of solvent-borne paint to
reduce the volume of solvent waste without affecting product quality. Sound experience and
knowledge of the chemistry of the paint formulations are needed to plan a reuse protocol for a
particular facility. This technology system can produce cost savings with little capital outlay for
implementation and little or no increase in operating expenses.
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Other companies besides Vanex are using a similar system. Jamestown Paint has identified
products in which wash solvents from other, compatible products can be used and has set up a system
for storing and reusing wash solvent whenever possible (Maty, 1993). Other companies reuse wash
solvent in different ways to reduce waste. For example, Red Spot Paint & Varnish Co. reuses cleaning
solvents for multiple cleaning operations until the solids content is higher than 1.5% before off-site
recycling. This change is reported to have reduced their wash-solvent volume from 1000 gal per day
to 100 gal (Beels, 1990; Ruthenburg, 1993).
Using the production figures for solvent-borne coatings and the Vanex wash-solvent recovery
rate, it is possible to estimate the impact that this technology could have on wash-solvent waste
reduction per year in the U.S. According to U.S. Department of Commerce figures for 1992,
production of paints in the U.S. was 1.10 billion gal (Bureau of Census, 1993). This production is
reported for three coatings groups: architectural coatings, industrial-product coatings, and special-
purpose coatings. There is significant lack of agreement in the technical literature between available
industry figures and market-share analyses concerning the volume of solvent-borne coatings
manufactured in the U.S. each year. However, it is well accepted that environmental pressures are
decreasing the percentage of solvent-borne coatings produced. The percent of coatings produced in
the U.S. in 1992 that are solvent-borne has been cited from a low of 62% to a high of 75% (Paint &
Resin, 1991; Mercuric, 1992; Seymour, 1991; Schrantz, 1993). Because the percentage is decreasing
yearly, Battelle based calculations of potential impact on the low 1992 percentage of 62% (682 million
gal).
As the calculations in Table 10 show, equipment cleaning in production of solvent-borne paint
may generate as much as 13.6 million gal (248,000 55-gal drums) of wash-solvent waste. Recovery
of 80% of this wash solvent could reduce the volume of solvent waste requiring disposal from 13.6
million gal to 2.7 million gal, a reduction of 10.9 million gal.
This evaluation of the wash-solvent recovery system at Vanex has accomplished the program
objectives for product quality, pollution prevention potential, and estimation of economics. Wash
solvent used in the manufacture of similar solvent-borne paint did not lower product quality. Solvent
waste entering the wastestream was reduced by 60 drums per year at Vanex, and no additional
pollution was produced by the technology. The payback period for implementation was about one
month. Many small-to-medium paint manufacturers could use a similar practice to reduce solvent
waste from the manufacture of solvent-borne paint.
28
-------
TABLE 10. ESTIMATE OF ANNUAL WASTE REDUCTION IF WASH
SOLVENT REUSE IMPLEMENTED THROUGHOUT THE U.S.
Assumptions Based on Industry Data:
Annual production of solvent-borne paints:
Estimated number of batches @ 1,000 gal/batch:
682 million gal
(2,580 million L)
682,000 batches
Quantity of mineral spirits used to clean
tanks and equipment between batches:
20 gal/batch
(75 L)
Wash Solvent Reduction Calculations:
Without Reuse
Solvent required for cleanup only
(682,000 batches X 20 gal/batch)
Wash solvent disposed
With 80% Reuse
Solvent required for cleanup
(682,000 batches X 20 gal/batch)
Solvent reused for formulation
(80% X 13.6 million gal)
Wash solvent disposed
(13.6 - 10.9 million gal)
13.6 million gal
(51.5 million L)
13.6 million gal
(51.5 million L)
13.6 million gal
(51.5 million L)
10.9 million gal
(41.3 million L)
2.7 million gal
(10.2 million L)
Waste Reduction
10.9 mijlion gal
(41.3 million L)
29
-------
SECTION 7
REFERENCES
American Society for Testing and Materials. 1992. Annual Book of ASTM Standards.
Battelle. 1993. Quality Assurance Project Plan (QAPP) for Waste Solvent Reuse in Paint
Production. Submitted to U.S. EPA by Battelle, Columbus, Ohio.
Beels, G. 1990. "The Pollution Solution—Reducing Waste in Paint Manufacturing." Industrial
Finishing, March, 1990, E-32.
Greenfield, D. 1993. "Award Winners Slow Waste Flow to a Trickle." Modern Paint and
Coatings 83(1):6-10.
Maty, J. 1993. "Winning the War on Waste." American Paint & Coatings Journal, May 17,
1993, 36-42.
Mercuric, A. 1992. "Advances in Water-Borne Coatings for the 1990s." American Paint &
Coatings Journal, January 20, 1992, 36-45.
O'Neill, D. 1992. "Small Company, Big Recognition: Southern Illinois-based Vanex Color Reaps
Honors, Benefits From Efforts to Reduce Waste Generation." American Paint Journal,
76(44) :38-43.
Paint & Resin. 1991. "Rapid Growth Seen for Water-Borne Coatings." Paint & Resin, June 15,
1991, 14-15.
Ruthenburg, J.C. 1993. "Waste Minimization Pays Big Dividends at Red Spot Paint Co."
American Paint & Coatings Journal, 77(52):42-45.
Schrantz, J. 1993. "Industry Outlook:HeaIthy." Industrial Paint & Powder, 69(10):20-23.
Seymour, R.B. 1991. "New Horizons in Waterborne Coatings." Paint & Resin, October 1991,
14-15.
U.S. Department of Commerce. 1993. Paint, Varnish, and Lacquers. Bureau of the Census,
Current Industrial Reports.
30
-------
APPENDIX
RAW DATA FROM LABORATORY ANALYSIS
TABLE A-1. 60° GLOSS READINGS USING HUNTERLAB D48D GLOSSMETER
Sample No.
46481-4-1
46481-4-2
46481-4-4
46481-7-1
46481-7-2
46481-7-4
60° Gloss Readings*
1
81.6
81.5
82.0
79.3
80.1
79.0
2
81.6
81.2
81.7
79.2
79.9
78.9
3
81.6
81.3
82.0
79.8
80.2
78.7
Average
81.6
81.3
81.9
79.4
80.0
78.9
At the 95%-confidence level, all data are valid, i.e. differ by no more than 0.9
gloss units for determinations of same sample.
31
-------
TABLE A-2. HEGMAN GRIND
Sample No.
46481-4-1
46481-4-2
46481-4-4
46481-7-1
46481-7-2
46481-7-4
Battelle
Hegman Units*
(average of three readings)
8
7-3/4
8
8
8
8
* At the 95%-confidence level; all data are valid, i.e differ by no more
than 3/4 Hegman units for the same sample.
TABLE A-3. RAW DATA* FOR VISCOSITY AT 25°C
Reading, cps
Sample No.
46481-4-1
46481-4-2
46481-4-4
46481-7-1
46481-7-2
46481-7-4
1
4175
3925
3900
4125
3875
3850
2
4150
3925
3950
4125
3875
3862
3
4150
3950
3950
4150
3950
3900
Raw data as recorded. Three digits are significant.
32
-------
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-------
TABLE A-5. RAW DATA FROM COLOR DIFFERENCE MEASUREMENTS USING CIELAB*
Sample #
46481-4-1
46481-4-2
46481-4-4
46481-7-1
46481-7-2
46481-7-4
L
93.71
93.65
93.67
93.84
93.88
93.81
A
-1.58
-1.49
-1.60
-1.58
-1.61
-1.57
B
1.77
1.68
1.69
1.93
1.97
1.98
Yl
2.53
2.43
2.35
2.85
2.90
2.96
AE
0.2
0.2
0.2
t
t
t
* Macbeth MS-2000, Illuminant C; each reading is the average of three readings.
t Results of 7-1, 7-2, and 7-4 averaged for use as standard for color difference calculations.
TABLE A-6. DENSITY DETERMINATION DATA FOR VANEX 2-1 HOUSE PAINT AT 23 °C
Sample #
w
k/v*
Density, Ib/gal
Wash Solvent
4648 1-4-1 -A
46481 -4- 1-B
46481 -4- 1-C
46481-4-2-A
46481-4-2-B
46481 -4-2-C
46481-4-4-A
46481 -4-4-B
46481-4-4-C
241.05
241.06
241 .05
241.78
241.77
241.73
241.60
241.61
241.60
138.83
138.83
138.83
138.83
138.83
138.83
138.83
138.83
138.83
0.1001013
0.1001013
0.1001013
0.1001013
0.1001013
0.1001013
0.1001013
0.1001013
0.1001013
10.23
10.23
10.23
10.31
10.30
10.30
10.28
10.28
10.28
New Solvent
4648 1-7-1 -A
46481 -7-1 -B
46481 -7-1 -C
46481 -7-2-A
46481-7-2-B
46481 -7-2-C
46481-7-4-A
46481-7-4-B
46481-7-4-C
Distilled Water
Distilled Water
Distilled Water
241.59
241.60
241 .60
239.51
239.57
239.55
242.41
242.60
242.48
221.99
222.00
222.00
138.83
138.83
138.83
138.83
138.83
138.83
138.83
138.83
138.83
138.83
138.83
138.83
0.1001013
0.1001013
0.1001013
0.1001013
0.1001013
0.1001013
0.1001013
0.1001013
0.1001013
0.1001013
0.1001013
0.1001013
10.28
10.28
10.28
10.08
10.08
10.08
10.36
10.38
10.38
8.32 at23°C
8.33 at23°C
8.33 at23°C
W = weight of cup plus sample.
t W = weight of cup empty.
t k/v = factor specific to actual cup used in testing calculated in cup calibration process, ASTM
D1475.
35
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