Case Study No. 9 High-Solids Coatings
Design Fabricators
Lafayette, CO
Background
Design Fabricators produces custom store
fixtures and entertainment/ornamental items.
Most of their production consists of coated
wood products made from sheet goods; 60 to
70 percent of the coatings are clear sealers
or topcoats. A small percentage of the
coatings, five to ten percent of total sales, are
used to coat metal or fiberglass. The plant
operates five days a week with two shifts.
The number of hours worked and number of
employees vary seasonally, but averages
close to 200 employees on two 8-hour shifts.
Approximately 25 of those employees are in
the finishing department.
Product sample
in October 1994, Design Fabricators moved into their current location. Prior to the
move, the local community raised concerns over emissions and the odor of the solvent-
borne coatings. The company was interested in pursuing new finishing techniques and
lowering emissions, but they found that information about low-VOC/HAP coatings was
not readily available. By November 1995, alternative coatings were under serious
consideration and were being tested for quality, durability, and cost effectiveness. The
new coating system was fully implemented in early 1996.
Manufacturing and Coating Operations
Most commonly, raw material is
purchased in sheet form. The sheet
goods are then cut to size and edged
with laminate or wood tape if necessary.
Both processes are automated. Some
solid woods, which need to be ripped,
planed, and milled, also are used for
products such as tables and benches.
The components are then taken directly
to either the assembly area or the
finishing department. Depending on the
product, it may be finished before or Finishing department
after assembly. In the assembly area, there are specified areas for different jobs.
Products are assembled and sanded by hand. In the finishing department, the product
is taken into one of the two spray booths and placed on hangers (the larger items are
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rolled in on trolleys). The hangers
are moved manually throughout
the finishing area, with the
operators taking care not to touch
the product until the finish is
cured. Most of the coatings are
applied using air-assisted airless
guns, although a small number of
custom jobs require conventional
spray guns. The coatings are
pumped from 55-gallon drums in
the paint kitchen directly to the
spray guns in the booths. The
only exception is the catalyzed
conversion varnish, which is mixed in 5-gallon batches and put into smaller pumps
located in the spray booth. The stain is applied first and is hand wiped for some
products. The product then is sprayed with a sealer and sanded. Finally, a topcoat is
applied and the product is allowed to air dry. After the finish has cured, the product is
packaged and shipped to the customer.
Conversion to High-Solids, Low-HAP Finishes
Design Fabricators tested several different coatings and suppliers before settling on
their current finishing system. First, waterborne coatings were used on some of the
smaller orders, but they caused several problems. The biggest problem was grain
raise. When a waterborne product is applied to wood, especially the softer species,
the grain of the wood absorbs the water and stands up, or raises. Grain raise results in
a rougher finish that lacks the smoothness that is typically achieved using solvent-
borne coatings. In an attempt to rectify this problem and smooth the grain, additional
sanding was required. However, the operators often sanded through the seal coat.
This would cause the grain to raise again when the topcoat was applied because the
wood was re-exposed to a waterborne coating.
Another problem encountered with the waterborne coatings was drying time. To
prevent the parts from sticking together, waterborne products generally require a much
longer drying time before they can be stacked or shipped. This problem can be helped
by adding drying ovens to speed the curing process. However, additional equipment
would not only be expensive, but would also require more space than the facility can
devote to finishing, A third problem Design Fabricators encountered with their
waterborne coatings was a softer finish that was not as durable. Because of these
difficulties, waterborne coatings were not chosen for the new system.
Design Fabricators next considered UV-cured coatings. Ultraviolet-cured coatings
have the low-VOC/HAP advantage of waterborne products while producing a durable,
high-quality finish. Grain raise is avoided because UV-cured coatings can have up to
100 percent solids and no water. The very-high solids content prevents the VOC and
HAP emissions associated with traditional solvent-borne coatings. The curing time also
Product assembly
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is very short, only a few seconds. However, UV-cured coatings are most feasible for
flatline finishing, making UV finishing impractical for Design Fabricators because of the
wide variety of shaped pieces that they finish.
The final coating system tested by Design Fabricators included a high-solids catalyzed
conversion varnish and low-HAP sealers and stains. The VOC and HAP content of
these coatings is still low due to the high solids content, and the problems experienced
with the waterborne coatings tested by the facility were avoided because the coating is
acetone based. The acetone-based coatings are applied using spray guns, allowing
easy finishing of shaped pieces. The main problem with acetone-based finishes is that
they tend to dry too quickly. However, drying time may be adjusted by adding other
solvents. Acetone also is very flammable, and fire risks are an important issue.
However, because of the high-quality finish and compatibility with the existing finishing
line, the high-solids, low-VOC/HAP system was selected. The new topcoat has around
40 percent solids, where the old topcoat had about 18 percent solids. Gradually, the
old precatalyzed topcoats are being phased out and replaced with the high-solids
catalyzed conversion varnishes. Catalyzed finishes have a higher solids content and
result in a more durable finish. The harder finish is achieved because the coating is
not only dried, but is cured by a polymerization reaction controlled by the amount of
catalyst in the coating.
The transition to high-solids coatings was fairly smooth for Design Fabricators. There
was a learning-curve period of six to eight months during which the operators became
familiar with the new coatings and different coatings combinations were tried to achieve
the best finish possible. Because the new system is compatible with the original
solvent-borne system, the operators were able to make the minor adjustment rapidly.
The coating process did not undergo much change when the coatings were changed.
The new coatings are applied manually using spray guns, as were the old coatings.
Costs
Although the new finishes cost more per gallon ($18 per gallon versus $11 per gallon
for the topcoat), the overall costs are approximately the same because of the higher
coverage associated with high-solids coatings. Design Fabricators feels any slight
increase in cost is worthwhile; the high-solids finishes are not only lower-emitting, they
also produce a quality finish equal to, if not better than, the original solvent-borne
system.
Emissions
According to data provided by the facility, the switch to high-solids coatings resulted in
a considerable decrease in the annual VOC and HAP emissions for the plant. The
coatings changes also served to address the local community's concerns about their
emissions. The new coatings typically average around 1 pound of VOC per pound of
solids. In 1995, before beginning the switch to the lower-emitting coatings, around
44 tons of VOCs were emitted. After the complete conversion to the new system, only
about 36 tons of VOCs were emitted over a 12-month period. Although the difference
seems small, the company's sales increased during that two year period ($10.1 million
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in 1995 versus $13.7 million in 1997). Design Fabricators was able to increase
production and still lower their total mass emissions and their emissions per dollar of
sales.
The reduction in HAP emissions was even greater. In 1995, approximately 20 tons of
HAPs were emitted. By 1998, HAP emissions were almost eliminated, while production
nearly doubled. The new coatings contain from 0.04 to 0.46 pound HAP per pound of
solids. In addition, the glues, cleaning solvent, and stain base contain no HAPs.
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