Office or Toxic Substances,
United States Environmental Protection Agency
June, 1981

grffl <£>^3
Mention of any product: or company names does not constitute
recommendation or endorsement by the Environmental Protection
Agency or by any of its contractors.

Introduction	v
Chapter One. Advantages and Disadvantages	1
of the Use of Encapsulants
Chapter Two.	The Choice Between 3ridging
and Penetrating Encapsulants	9
Chapter Three. Choosing the Right Encapsulant	14
Chapter Four.	Latex Paints: For Use Only
on Ceraentitious Materials	17
Chapter Five: Encapsulant Application	19
Appendix:	A Test which Indicates Whether
Friable Asbestos-Containing Material
Can Sustain the Weight of an
Encapsulant	25
1.	Appropriate Situations for the Use of Encapsulants
2.	Comparison of Bridging and Penetrating Encapsulants

As part of its program to address the problems caused by friabie
asbestos-containing materials in buildings, the Environmental
Protection Agency has written these Guidelines for the Use of
Sncapsulants on Asbestos-Containing Materials. The practice of
applying an encapsulant to asbestos-containing materials in
buildings in order to control the release of asbestos fibers is
called encapsulation.
The first chapter of this document discusses the advantages and
disadvantages of encapsulation. It is written primarily for -
building owners ana school administrators who have identified
asbestos problems, and is intended to help them decide whether
encapsulation is appropriate in their buildings.
The rest of the document discusses the points to consider when
choosing an encapsulant and the techniques to use when applying
it. This information should be useful to contractors who are
performing encapsulation jobs, as well as to building owners and
school administrators who are preparing contract documents for
encapsulation work or are monitoring work in progress.
The entire document should be used in conjunction with another
SPA publication entitled Asbestos-Containing Materials in School
3ulldinas: A Guidance Document. SPA strongly advises that
anyone concerned witn asoestosproblems in buildings consult
Asbestos-Containing Materials in School Buildings: A Guidance
Document, wnicn discusses in detail tne advantages and
disadvantages of various ways to prevent or reduce exposure to
asbestos. It also discusses proper work practices and worker
protection procedures which apply to removal, enclosure, and
encapsulation jobs.
Copies of Asbestos-Containing Materials in School Buildings: A
Guidance Document are availaole from EPA's Industry Assistance
Office; call toll free 800-424-9065 (in Washington, DC, 554-
1404) .
In addition to Asbestos-Containing Materials in School
3uildinos: A Guidance Document, EPA's Industry Assistance Office
aistributes information on. commercially available encapsulants,
offers individual guidance, and provides the names and addresses
of experts in SPA's Regional offices whom contractors, school
administrators, and building owners can contact for further
assistance. Any interested party is encouraged to call the
Industry Assistance Office.

This guidance document; was prepared by tne Chemical Control
Division of SPA's Office of Toxic Substances with the help of
Mr. William Mirick of Battslle Columbus Laboratories. A number
of EPa and outside experts have reviewed earlier drafts of the
document, and their comments are reflected in this final version.
This document should not be confused with the reports on
encapsulants prepared by 3attelle Columbus Laboratories: their
purpose is to evaluate specific commercially available products,
while this document is intended to provide general guidance on
wnen and how to encapsulate asbestos-containing material.
The guidelines in this document for deciding whether
encapsulation is advisable and for determining what encapsulant
to use are based on the best technology presently available, but
adherence to the guidelines will not necessarily insure that the
proper decisions will be made. Similarly, although the
guidelines for application of encapsulants in Chapter Five are
based on the best currently available technology, and are
designed to reduce building contamination and exposure of workers
to asbestos, adherence to them will not necessarily guarantee a
risk-free procedure for asbestos encapsulation.

Encapsulation can solve some asbestos exposure problems easilv
and adequately. In other situations, however, encapsulation Is
dennitely not advisable, and attempts to use encapsulants in
these situations may lead to greater exposure oroblems than wou^
have occurred if nothing had been done."
Encapsulation is often advisable in situations where the
asbestos-containing material is virtually impossible to remove.
For example, asbestos was often spray-applied to extremely
complex surfaces, such as pipe and duct work or ceilings v' th
numerous surface irregularities. Since it would be very
difficult to remove asbestos from such conrolex surfaces,
encapsulation may be a good solution. The"use of encapsulants is
often also advisable on denser, harder materials (cabled
"trowelled-on" or_"cementitious") which contain asbestos.
Although cementitious materials typically do not oresent excosu^a
problems as severe as those caused by fluffy or spongy asbestos-
containing materials, it may be advisable to encapsulate them as
a precaution against future deterioration and damage.
However, encapsulation_is not always advisable even in these
situations.^ Often it is not as easy and inexpensive as it may
appear at ^irst. Further, using an encapsulant on asbestos—
containing fireproofmg material may affect the material's
fireproofing ability, causing problems with the building's fire
rating and ^ire insurance. Encapsulating asbestos—containing
material may also make it difficult to remove the material later
in compliance with c
nand pressure.* Fluffy, spongy asbestos-containing materials are
often hignly friable; if they are, they should not be
encapsulated (see below, page 4).
Given all these variables, the performance of an encapsulant on a
particular piece of asbestos-containing material is
unpredictable. The problem is complicated by the fact that a
given encapsulant may perform very differently when applied to
two different types of material. It may perform extremely well
on one material and fail completely on another. For this reason,
EPA strongly recommends that any encapsulant be tested in the
field on the actual material before a final decision to use it is
made (see Chapter Five, page 21).
The remainder of this chapter discusses some of the advantages
and disadvantages of the use of encapsulants. Each of these
should be considered carefully before any decision is made to
Advantages of Encapsulation
1. Encapsulation can control asbestos exposure problems
without necessitating the removal of the asbestos-
containing material.
Encapsulation may be a practical means of preventing the release
of asbestos fibers into the air and reducing the building users*
exposure to asbestos. Since it should make the removal of the
asbestos-containing material unnecessary, encapsulation retains
most of the advantages of having the material in the building.
Encapsulation avoids the expense and additional time required to
replace the asbestos-containing material, which is often
necessary after removal jobs.
2. Encapsulation is usually the quickest method of
Encapsulation is a less complicated task than the removal of the
asbestos-containing material or the construction of barrier
systems. Removal, in particular, is likely to be a more involved
and time-consuming process, especially since the asbestos-
containing material must often be replaced with a similar, but
asbestos-free, product (fiber glass or cellulose, for example).
* See Asbestos-Containing Materials in School 3uildings: -A
Guidance Document, Part 1, pages 3 and 13, for a more
detailed discussion of friability.

However, this difference in time requirements is not as great as
it may appear at first glance, since certain measures to protect
t;ie workers ana to prevent contamination of tne outside air are
necessary during any corrective action (removal, enclosure, or
encapsulation). These measures add to the time required for any
of these techniques.*
3. Encapsulation is usually the least expensive control
method in the short run.
Since encapsulation is a simpler process than removal, it is
usually less expensive. Prices for any sort of asbestos control
vary widely, depending on local wage rates, the type and location
of the surface area, and the materials which are used.
One should bear in mind that the real cost of any asbestos
control technique is likely to be greater than it first appears,
because factors other than the basic cost of the job must be
included. For example, the costs of periodic inspection for
damage and aging should be included in an economic analysis of
encapsulation. The long-term costs of using encapsulants may
also include periodic recoating, a consideration which may make
encapsulation much more expensive than it looks at first.
4. Encapsulation is often a good control method for
cementitious asbestos-containing material.
Ceraentitious materials are usually composed of asbestos and other
materials (e.g., vermiculite and perlite), mixed with cement.
They are dense and usually fairly hard, and have a coarse,
textured appearance. Although they can be damaged by hand, they
are not fluffy or spongy. They are less than 3/4 inch thick
(usually 1/3 inch to 1/2 inch) and usually contain less than 15%
asbestos. Ceraentitious materials can deteriorate with age and
can be friable, but in general they do not present exposure
problems as severe as those caused by fluffier materials because
their asbestos content and friability tend to be lower.
For cementitious materials in good condition, encapsulation is
often a good solution because it can help to control future
release of fibers easily and inexpensively. However, if
ceraentitious material is water damaged or accessible to the
The protective measures are discussed in Chapter Five of this
document, and in Asbestos-Containing Materials in School
Buildings: A Guidance Document. Furtner information is"
available directly from EPA's Industry Assistance Office (see

building's users, or if it is no: firmly adhering to the
substrate, it should not be encapsulated (see below).
Disadvantages of EncaDsulation
1. The asbestos source remains in the building.
Encapsulation controls the release of fibers from asbestos-
containing material, but it does not provide a lasting solution
since the asbestos remains in the building. For this reason, the
encapsulated material must be checked periodically to ensure that
the encapsulant coat has not been damaged. Whenever the building
is renovated, or whenever repair work is conducted near the
material, the workers must be careful not to damage the sealed
asbestos-containing material. It also appears that encapsulants,
once applied, will deteriorate over time, and that the need for
recoating will recur periodically throughout the life of the
2.	Encapsulated material may be difficult to remove in
compliance with SPA regulations.
When the building is eventually demolished, or when the asbestos-
containing material has to be removed, another serious problem
may occur. Under EPA regulations, before any building containing
friable asbestos-containing material is demolished or before any
friable asbestos-containing material is removed from a building,
the material must be wetted down (to prevent the release of
asbestos fibers into the environment), removed separately, and
Since encapsulants generally form a water-tight barrier, their
use makes subsequent wetting of the asbestos-containing material
difficult at best. Encapsulation may therefore make it difficult
to comply with EPA regulations during later removal or demolition
proj ects.
3.	Encapsulation is not suitable for asbestos-containing
material which has poor cohesive or adhesive strength.
Encapsulation should not be considered on any asbestos-containing
material with poor cohesive strength. Some material with poor
cohesive strength is friable; that is, it can be crushed or
reduced to powder in the hand. Even if material is not friable,
it may have poor cohesive strength: an example is material which
is separating from itself in layers. If materials with poor
cohesive strength are encapsulated, the weight of the encapsulant
may cause them to deteriorate or delaminate even faster.
Similarly, encapsulants should not be applied to asbestos-

containing material which has poor adhesive bonding to the
substrate. The substrate is the underlying surface (for example,
concrete or structural steel) to which the ascestos-containing
material has been applied. If an encapsulant is applied to
material with poor adhesion to the substrate, the additional
weight of the encapsulant inay cause the material to separate
completely from the substrate and fall.
A simple test which has been used widely to determine whether
asbestos-containing material has sufficient cohesive and adhesive
strength to sustain the weight of an encapsulant is described in
the appendix to this document (page 25).
4. Encapsulation is not suitable for materials which are
accessible to the users of the building.
Encapsulants are designed to withstand some impact and
abrasion. However, EPA knows of no encapsulant which can
withstand repeated impact, and if encapsulated material is
damaged by accident or vandalism asbestos fibers may be
released. This problem is one of the major limitations of the
usefulness of encapsulants.
Because of this limitation, encapsulation should not be
considered on asbestos-containing materials which are accessible
to, or routinely disturbed by, the building's users. Surfaces
which are less than about ten feet from the floor or are
routinely disturbed during maintenance, as well as surfaces such
as the ceilings of gymnasiums (which can be damaged by balls and
other objects), should not be encapsulated.
5. Encapsulation is not suitable for water damaged
In any case where the asbestos-containing material has been
damaged by water from roof or plumbing leaks, or where such
damage might occur, encapsulants should not be used. Water
leaking through asbestos-containing material will dissolve some
of the binders that hold it together and to the substrate. This,
means that water damaged materials tend to have poor adhesive and
cohesive strength, and encapsulants are not appropriate for such
In addition, if areas subject to water damage are encapsulated,
water may be trapped in the material behind the encapsulant,
dissolving still more of the binding agent. Eventually the
combined weight of the encapsulant and the trapped water may
cause the asbestos-containing material to fall,"taking the
encapsulant layer with it and releasing asbestos fibers into the
surrounding air.
If the source of the water damage is repaired and the damaged

material is selectively removed and replaced, encapsulation may
oe considered if the other conditions outlined in this chapter
are met.
6. Encapsulation is not advisable for asbestos-containing
materials more than one inch thick.
Encapsulation also should not be considered on asbestos-
containing materials which are more than an inch thick. Tests
have indicated that even the best penetrating encapsulants, which
are designed to saturate asbestos-containing material and bind it
together and to the substrate, cannot completely penetrate
material which is more than one incn thick.* Users of
encapsulants should not expect penetration of greater than one
inch; tnerefore, encapsulants cannot be expected to improve the
adhesion of a thicker material to the underlying surface. The
weight added to the material by any bridging or penetrating
encapsulant may cause a failure of the material's cohesive or
adhesive strength. The exception to this rule is asbestos-
containing material insulation material on pipes and ducts, which
may be suitable for encapsulation even if it is more than one
inch thick.
7.	Encapsulation is not advisable in buildings and rooms
which are subject to vibration.
Vibration appears to possess the ability to shake spray-applied
asbestos-containing material from the substrate even if the
material has been encapsulated. In buildings and rooms which are
subject to high vibration, encapsulation is not advisable. This
problem is most serious in airports, in buildings near heavily
travelled roadways or railroads, and in rooms with heavy
machinery or fans. However, EPA also recommends strongly that
asbestos-containing materials in rooms beneath gymnasiums and
other high-activity areas not be encapsulated.
8.	Encapsulation of asbestos-containing fireproof i.^g
material may reduce the fireoroofing qualities of the
Asbestos-containing material often functions in buildings as
fireproofing. If it is encapsulated, its fireproofing qualities
may be impaired. This, in turn, may affect the fire rating of
the building.
* The tests are described in Evaluation of Encapsulants for
Soraved—On Asbestos-Containing Materials in 3uildings, a
report preparec :or EPA oy 3atcelie Co-i-umous Laooracories.

SPA is currently conducting further research into this aspect cf
encapsulation. Although it does not preclude consideration of
the use of encapsulants, building owners may wish to consider
this factor before making a decision to encapsulate.
9. Encapsulation may reduce or destroy the acoustical
properties of the asbestos-containing material.
Asbestos-containing materials were often applied for acoustical
insulation. If an encapsulant is applied to asbestos-containing
material, the ability of the material to deaden sound tends to be
However, this factor does not, by itself, preclude the
possibility that encapsulation is feasible. The other techniques
for controlling asbestos exposure also have detrimental effects
on the acoustical properties of asbestos-containing materials.
Enclosure may also reduce the acoustical properties of the
material. If asbestos-containing material is removed, it often
must be replaced by an environmentally acceptable substance with
similar acoustical qualities, such as fiber glass or cellulose.
* * *
In summary, encapsulation can be a practical method to control
the release of asbestos fibers, but certain limitations make it
useful only in a relatively small number of cases. Where
asbestos-containing material is accessible to the users of the
building, has poor cohesive or adhesive strength, is water
damaged, or is more than an inch thick, encapsulation is not
recommended. Encapsulation is also not recommended on friable
materials. EPA estimates that encapsulation is an appropriate
control technique in no more than 10% to 15% of all cases where
asbestos-containing material requires corrective action.
The following chart combines most of the information presented in
this chapter in a simple format designed to help b-iilding owners
and scnool administrators decide whether encapsulation is
apDropriate in their buildings. It is designed on.1-/ to
suDolement the discussion and should not be used by itself.


If tne decision to encapsulate has already been made, the next
question is whether to use a bridging or a penetrating
encapsulant. The purpose of a bridging encapsuiant is to form a
tough membrane over the surface of the asbestos-containing
material which should prevent the release of asbestos fibers. A
penetrating encapsulant is designed to saturate the material and,
as it dries, to bind the asbestos fibers to one another and to
the other substances in the material.
Penetrating encapsulants, in general, have lower viscosities than
bridging encapsulants. This means that they are thinner and flow
more easily. Viscosity is measured in centipoises; water, for
instance, has a viscosity of one centipoise. Penetrating
encapsulants usually have viscosities up to one hundred
centipoises, while many bridging encapsulants are so thick that
their viscosity is measured in thousands of centipoises.
Penetrating encapsulants usually also have a lower solid content
than bridging encapsulants.
Another difference between bridging and penetrating encapsulants
is that bridging encapsulants are almost always pigmented for
aesthetic purposes. On the other hand, almost no penetrating
encapsulants contain pigment because its presence would inhibit
their penetration. Dyes (not pigments) can be added to
penetrating encapsulants to color them (see Chapter Five, page
The choice of what kind of encapsulant to use often depends on
the characteristics of the material which is to be
encapsulated. This chapter discusses a number of characteristics
of asbestos-containing material and shows how each affects the
choice between bridging and penetrating encapsulants.
As explained in Chapter One, material with high friability should
not be encapsulated. If, however, the decision has been made to
encapsulate asbestos-containing material which is moderately
friaole and less than one inch thick, penetrating encapsulants
are preferable. Penetrating encapsulants are designed to reduce
the friability of the material by soaking into it, binding the
fibers together, and increasing the material's cohesive strength.
Because bridging encapsulants are not designed to penetrate into
the asbestos-containing material, they will not increase its

cohesive strength. The use of bridging encapsulants on friable
material may make the problem worse, because the weignt of the
encapsulant may make the material delaminate even faster.
There are two exceptions to this point; One is discussed below
(page 12) in the section on the shape of the surface: for
friable asbestos-containing material on complex surfaces such as
pipes and ducts, a bridging encapsulant may actually be
preferable to a penetrating one. The second relates to
ceraentitious materials, which, even if they are somewhat friable,
may be treated with a bridging encapsulant (see pages 11-12).
water Damage
With regard to water damaged materials, there is no real
distinction between bridging and penetrating encapsulants. For
the reasons given in Chapter One, water damaged material should
not be encapsulated.
Imperfect Adhesion to the Substrate
Asbestos-containing material which adheres imperfectly to the
substrate should not ordinarily be encapsulated either with
bridging or with penetrating encapsulants, since the additional
weight of the encapsulant may cause the material to fall. If an
encapsulant penetrates all the way through the material to the
substrate and binds it to the substrate, this problem may be
avoided, but this will not often be the case.
Bridging encapsulants, which are not designed to penetrate
through the material, will obviously not improve the material's
adhesion to the underlying surface. Most penetrating
encapsulants penetrate less than an inch into spray-applied
asbestos material, and are unlikely to bind thicker asbestos-
containing materials to the substrate. If the material adheres
imperfectly to the substrate, it should be removed or enclosed
rather than encapsulated.
Most surfaces in any building are occasionally exposed to damage
from the building's users,. On surfaces for which this exposure
occurs routinely, encapsulation is not recommended (see Chapter
One, page 5). If, however, the decision is made to use an
encapsulant on a surface which is disturbed occasionally by
custodians and maintenance workers, a penetrating encapsulant is
probably preferable.

Tests conducted for EPA indicate that penetrating encapsulants
are sligntly more susceptible to damage from impact and abrasion
than bridging encapsulants.* However, the consequences of
failure in the case of a bridging er.capsulant are liXely to be
more severe. The membrane created by a bridging- encapsulant
covers, but does not bind, the asbestos fibers behind it. If
this membrane is damaged, fibers can easily escape into the
air. Penetrating encapsulants, on the other hand, should
continue to hold the fibers in clumps, preventing their
widespread release into the air.
However, the use of a penetrating encapsulant is no guarantee of
success. If asbestos-containing material which has been treated
with a penetrating encapsulant is damaged, the clumps of fibers
falling'to the floor may be ground underfoot and may eventually
bring about increased levels of exposure. Further, unless the
encapsulant has penetrated completely through the material,
unencapsulated material may be exposed when the encapsulant is
damaged. Hence, although penetrating encapsulants are preferable
to bridging encapsulants on material which will be exposed to
human contact, the best solution for material which is frequently
contacted is removal or enclosure.
Acoustical Properties
Asbestos-containing material which serves as acoustical
insulation (e.g./ in auditoriums and theaters) is liJcely not to
function as well after any encapsulant has been applied.
Sprayed-on material absorbs sound because of its dead air spaces
and because of its irregular surface. Penetrating encapsulants
reduce the dead air space, while bridging encapsulants create a
smooth layer on the surface. Either will impair the material's
acoustic properties to some extent.
Cementitious Materials
Cementitious materials are described in Chapter One, page 3, and
in Chapter Four, page 17-. It, is important to recognize the
distinction between cementitious materials, which are dense and
relatively hard, and fluffy, spongy asbestos-containing
materials. Although both may deteriorate with age and either may
be friable, cementitious materials typically present less severe
exposure problems because of their thinness, lower susceptibility
to damage, and generally low asbestos content.
* The tests are described in Evaluation of Sealants for
Soraved-On Asbestos-Containing Materials in 3uildings (see
cootnote to page 5).

For ceraentitious materials/ a bridging encapsulant is preferable
to a penetrating encapsulant. A bridging encapsulant should
effectively prevent the release of fibers from cementitious
materials. If the material is hard, completely undamaged, and
inaccessible to building users, the use of a good quality latex
paint with a high rubber content may also provide adequate
protection against future fiber release (see Chapter Four).
The Shape of the Surface
Asbestos-containing material on a large, flat ceiling without
projecting beams or other irregularities is not well suited to a
bridging encapsulant, unless the material is ceraentitious and in
good condition. On complex surfaces involving numerous beams,
pipes, and ducts, however, a bridging encapsulant may well be
preferable* It will wrap around the irregularities in the
surface, enveloping the material and binding it within the
continuous membrane of the encapsulant.
Surfaces Which Have Previously Been Encapsulated or Painted
Penetrating encapsulants are not suitable for use on material
which has already been encapsulated or painted. They cannot
penetrate the water-tight surface formed by the old coat of
encapsulant or paint, and thus cannot function properly. Heavy
accumulation of dirt or soot on the surface of asbestos-
containing materials may also prevent the penetration of
When recoating a surface that was previously encapsulated with
either a penetrating or a bridging encapsulant, a bridging
encapsulant should be used. It is important to choose an
encapsulant which can adhere to the older encapsulant layer: for
example, if a butyl rubber bridging encapsulant was used in the
first place, it is probably advisable to recoat it with a similar
product. Note that material which is poorly attached to the
substrate should roc be encapsulated, even if it has previously
been painted.
For material which has previously been treated with latex paint,
it may be advisable to recoat it with a good- quality, high rubber
paint (see Chapter Four).
A table summarizing the differences between bridging and
penetratihy encapsulants appears on the next page. It is
designed to supplement the discussion in this chapter and should
not be used by itself.

Bridging Penetrating
encapsulant encapsulant
Improves cohesive stren
The field of asbestos encapsulation is a new one, and both
contractors and building owners suffer from a lack of hard
information about how different encapsulants compare with one
anotner. This chapter offers general guidelines to help
contractors and building owners choose an encapsulant.
The best way to choose an encapsulant is to field test
encapsulants on the material to be encapsulated. When POf^ible,
field trials should be performed prior to the anal
an encapsulant. The information in this chapter, combined with
the knowledge gained from field tests, should insure that a
proper encapsulant is selected.
This chapter does not contain information on
For information on currently available encapsulants, please
contact EPA's Industry Assistance Office (see Introduction).
The American Society for Testing and Materials (ASTM) ^writing
standards by which encapsulants can be nudged. ASTM Plans to
publish these standards at some time m late 1981 or 1982.
This chapter is based on early versions of the ASTM standards.
It discusses a number of characteristics of encapsulants which
one should consider carefully before choosiijg a specific
Droduct These general characteristics can be used with the
in?flp7BaHrtn nn soecific products which is available from EPA s
lSdS«~^S!StaSce 0«i« to choose the best encapsulant for .
The first three characteristics are especially
important^ 'Siy IA toxicity, fl^Uitv, and method of
should not release toxic substances into the air
it is aSolied. Solvent-based encapsulants, or encapsulants
far which the* vehicle (the liquid in which the solid parts of the
are suspended) consists entirely of•hydrocarbons, are
®St ?ecomended because their use may be dangerous to workers.
For more information, contact ASTM at 1916 Race Street,
Philadelphia/ Pennsylvania 19103.

The roons where encaDSulants are applied should be isolated by
olast1' c' bar-ie^s * and if the encapsulant does release toxic
Plastic bar^e.s ano	workers could cuickiy be in
runes m tne enclosed space cue wu_.-*=i.=
serious danger.
The eneaDsulant also should not release any toxic materials after
it is dry? Even if it barns, the encapsulant should not release
toxic gases or an undue amount of smoke.
For information on the toxic ^as.|®?®*2nc*noff ice^or^rit*' to
Please contact tne EPA Industry	^rlirSances on
the manufacturers	^ Burfau of Standards's Technical
Holes 7lf ^d sea" Manufacturers should be willing to supply
this information?' since this is an important characterise of
any encapsulant.
The encapsulant, once applied, should not be flammable. This is
specially important because asbestos-containing material usually
serves as a fire retardant in buildings? use of an encapsulant
which impairs these fire retardant properties may endanger the
lives of the building's users.
Shcapsuian-t manufacturers generally run tests on their products
to insure that they will not increase the flammability of the
encapsulated material. By contacting the SPA Industry Assistance
Office, or by writing to manufacturers and asking for the results
for their products of ASTM Standard Test S 162, contractors and
building owners can get an idea of how encapsulants compare. SPA
recommends strongly that encapsulants be used which have Class
"A" fire ratings based on this test.
Method of Aoplication
rnt.	.	brush on friable asbestos-containing
.he use of a roller or b;rusia on d	fiber releaSe.
SSS £e*a&r=a& by spray e,uip*ent.
Encapsulants which.»ust *	^Ls'S^n
the asbestos-containing	therefore are more likely to
applied by airless sp'-«'from the surface of the material,
dislodge asbestos fibers from the
* See Asbestos-Containing Materials in School Buildings? a
Guidance Document, Fa£t 1, pp. 20-25, for information on
isolation of the work area. Further information is available
from SPA's industry Assistance Office.

Encapsulants which can be applied by airless spray equipment are
therefore preferable to those which must be applied by air
Other Qualities
There are six other characteristics described by 3attelle or ASTM
as desirable properties of encapsulants. The first four are
essential, while the last two are less critical. Each is
discussed briefly below.
The encapsulant should either penetrate into the material and
bing tne cioers cogetner, or cora a tough membrane over the
surface of tne material. These qualities are- discussed in
aetail in Chapters One and Two, and should be considered
The encapsulant should be able to withstand some abuse
witnout allowing the release of any fibers, particularly in
cases where the asbestos-containing material"is likely to be
occasionally disturaed.
3.	The encapsulant shoCtld be water insoluble when cured.
4.	The encapsulant should still have sufficient integrity, after
a minimum of six years, to allow recoating. In other words,
it should be fairly auraole.
5.	The encapsulant should not destroy the acoustical properties
or tne asbestos-containing material. This quality is"
ooviously more important in some cases than in others, and
any encapsulant will probably impair the acoustical
properties of the encapsulated material to some extent (see
above, pages 7 and 11). Building owners who plan to
encapsulate auditoriums or theaters may wish to contact an
acoustical consultant or acoustical engineer.
6.	The encapsulant should allow for topcoatlng bv conventional
pamcs wnere this is required for aestnetic reasons^ This
quality, again, will be more important in some cases than in
* * *
These guidelines, used in conjunction with the information
available from EPA's Industry Assistance Office, should help
contractors and building owners select an acceptable'
encapsulant. However, the best way to tell whether an
encapsulant will perform on a given surface is to field test it
by applying it to a small section of the surface (see page 21).
EPA recommends that several encapsulants be field tested in this
manner before a final decision is made regarding which one to
1 £.

The application of latex paint as a control technique for anv
asbestos-containing material which is fibrous, fluffy, spongy, or
highly friable is not recommended. Latex paints are not*designed
to encapsulate such materials and cannot be expected to do so
effectively. Latex paints should be considered for use only on
undamaged cementitious materials, such as acoustical plasters.
The major component of a cementitious, acoustical plaster is
usually a dense, non-fibrous mixture of granular material. The
only fibrous component is the asbestos, usually at a
concentration of less than 15%. This material has a coarse sand,
textured appearance and is most often 1/8 inch to 1/2 inch thick,
with a maximum thickness of 3/4 inch. Such materials are friable
if they are soft and can easily be indented by hand pressure, and
if a powder residue remains on the hand when the material is
If asbestos-containing material is unsuitable for encapsulation,
it is not suitable for application of latex paint either. The
limitations of latex paint are even more acute than those of
encapsulants, so latex paint should not be applied to any
asbestos-containing material which is water damaged, accessible
to the building's users, more than 3/4 inch thick, or adhering
poorly to the substrate.
Cementitious material may be considered for treatment with latex
paint if the material is in good condition, has not been damaged
by water,* and is not easily accessible. For cementitious
asbestos-containing materials which have previously been covered
with latex paint, a coat of good quality latex paint with a high
rubber content may be the most effective treatment because it is
most likely to adhere to the older layer of paint.
Although research on the use of latex paint to encapsulate
cementitious asbestos-containing materials has been very limited,
* If the cementitious material has small, isolated water
damaged areas, treatment with latex paint may be considered
if the source of the water damage is repaired and the damaged
material is removed and replaced. This applies only if the
material is otherwise in good condition and is not accessible
to building users.

trie following guidelines are offered to aid in the selection of
an appropriate latex paint.
Two ma^or components in latex paint are the pigment and the
vehicle (the vehicle is the liquid in which the pigment is
suspended? it contains mainly water). The label"should show the
percentage, by weight, of pigment and vehicle. Often the vehicle
percentage is subdivided into percent water and percent vehicle
resin solids or vehicle binder solids.
Good quality latex paint has a 60% or more vehicle content with a
high percentage of vehicle resin solids: of the vehicle, at
least 25% should be vehicle resin solids. If the percentage of
venicle resin solids is not stated on the label, it can be
determined by subtracting the percent pigment from the percent
total solids. In general, the higher the percentage of~vehicle
resin solids, the more durable and more flexible the coat of
paint will be. If the latex paint does not have a high
percentage of vehicle resin solids, it may be inflexible and
become brittle or crack with age. Accidental disturbance of the
coating by building users, or uneven settling of the building,
may easily crack or otherwise damage inflexible latex membranes,
allowing the release of asbestos fibers.
The application rate of latex paint should be 75 to 100 square
feet per gallon. This application rate should result in a
membrane with a dry film thickness greater than 4 mils
(0.004 inch). An airless spray gun should be,used to apply the
paint. E?A recommends that the ceoentitious material first be
sprayed with a light mist coat with the gun held 18 to 24 inches
away from the material. This light mist coat should seal loose
fibers into the surface and prevent the cementitious material to
continue to soak up the latex paint rather than build a
membrane. Once this has been allowed to dry completely, a
thicker coat can be added? this two-step application is
considered to be the first coat.
Wait until each coat dries before adding another one. Each
subsequent coat should be applied at a 90 degree angle to the
direction of the preceding coat application. This application
technique should prevent any holes or voids from being formed in
the membrane and should assure complete coverage of the
cementitious material.
Note that, in the application of latex paint, all die precautions
described in Chapter Five should be followed, just as though an
encajjsulant was being applied.
Once again, the use of latex paints should be considered only on
cementitious material in good condition. For any spongy or
jflu'f xiy'material containing asbestos, the use ot latex paints is
not recommended.

The importance of proper application of an encapsulant cannot be
overstressed. The quality of the contractors1 work will not only
determine the effectiveness of the encapsulation/ but may also
affect the health of the workers themselves.' Many failures of
encapsulated materials are due to poor application rather than
the quality of the encapsulant or the material that was
encapsulated. No encapsulant/ if improperly applied, can prevent
the release of asbestos fibers; careless procedures can easily
expose workers and the building users to asbestos, as well as"
involving additional costs to correct the problems caused by the
failure of the application. For these reasons, all contractors
wno are preparing to encapsulate asbestos-containing materials,
and all administrators who are writing contract documents, should
read this chapter carefully.
Applicable Regulations and Further Information
The Occupational Health and Safety Administration (052A)
regulates workplace practices and the levels of airborne asbestos
to which workers may be exposed. EPA also has issued regulations
which govern emissions from asbestos work and asbestos disposal,
and has developed general recommendations for use in preparing
encapsulation contracts* If the recommendations are used in
preparing contract documents, and if the contract specifications
are strictly enforced, workers and users of the building will bt
protected from undue exposure to asbestos.
Asbestos-Containing Materials in School Buildings: A Guidance
Document contains the complete text of the 0S3A ana EPA
regulations governing encapsulation work as well as sample
specifications for encapsulation contracts. Further information
on proper work area set-up, worker protection, and work practices
is available from the EPA Industry Assistance Office (see
Materials and Equipment
Encapsulation requires not only all materials standard for indoor
paint application but a number of others as well. Respirators
and disposable clothing for workers, as well as sealable
impermeable containers for the disposal of asbestos-contaminated
waste, are required by OSHa regulations. Plastic sheeting and
duct tape to seal off the work, area, and portable shower
facilities for worker decontamination, are recommended by EPA.

Contractors desiring mors information on materials should contact
tne EPA Industry Assistance Office.
EPA recommends that encapsulants be applied to the asbestos-
containing material with airless spray equipment. Although the
use of an airless gun does not completely eliminate the
dislodging of asbestos fibers during the encapsulation job, this
release is substantially less than is the case with conventional
air spray equipment.
.Worker Training
SPA strongly recommends that all workers be thoroughly educated
in a number of subjects related to encapsulation before they
begin work. These subjects include the use and maintenance of
respirators, the use of protective clothing, proper safety
procedures, personal decontamination procedures, techniques to
control fiber release in the work area, and proper application
procedures. OSHA requires that each employer establish a program
to train workers in the care and use of respirators and to ensure
proper storage of respirators when they are not in use.
Construction of Decontamination Area and Preparation of Work Area
Before encapsulation work begins, a decontamination area should
be constructed and the work area should be sealed off from the
rest of the building. These procedures are discussed in
considerable detail in Asbestos-Containing Materials in School
Buildings: A Guidance Document, so they are not treated
extensively here.
Briefly, the procedures involve the construction of a clean room
and a contaminated equipment room with a shower between them, and
with airlocks consisting of plastic curtains to prevent the
escape of fibers into the outside air. The work area should tog
completely isolated from the rest of the building with barriers
constructed from 4- to S-mil polyethylene sheets, and floors and
walls in the work area should be covered with polyethylene 5u.*-sts
as well.
Work Practices and Personal Decontamination Procedures
These topics, too, are covered in Asbestos-Containing .Materials
in. School 3uildinqs: A Guidance Document, and further
"Inrormation is available from £*a's industry Assistance Office.
Contractors and specification writers should avail themselves of
this information. Any person entering the work area must wear a
suitable respirator and disposable clothing. So clothing which
win be worn in the street can be worn in the work area. The
same also apolies to shoes: if shoes are worn in the work area,
they must be*left in the contaminated room at the end of each
work shift.

No one may remove bis or her respirator while in the work area.
l6ctvinQ til© wojt3c sxsa^ wo-rksrs niusw jtqitiovs wiisir
contaminated disposable clothing and, in the shower, saturate
UunlVM and their respirators thoroughly becore removing their
respirators. They should clean themselves and their respirators
thorougnly before changing into their street clothing.
Compliance with these specifications is necessary to protect the
health of the workers and prevent contamination of the outside
Field Testing of Encapsulants
SPA recommends that the contractor and building owner arrange to
field test several encapsulants before a final decision is made
as to which to use. This will not only insure that_the
encapsulant which is used is suitable for the material, but will
also enable the contractor to gain first—hand experience in
applying the particular encapsulant to the particular surface.
After the work area has been isolated with polyethylene from the
seat of the building, field test the encapsulants by applying
each to a small area of surface. The contractor should use the
techniques and orocedures he expects to use on the surface area
as a whole and*observe the results to see which encapsulant will
So the best job. He can also experiment with different drying
times, pressure settings, and so forth, and select the best
techniques when he begins the application©f the encapsu^ant
selected. In testing an encapsulant m the field, the building
owner should check that the encapsulant cures to a durable finish
in a reasonable time and that it adheres
containing material. He should also take a small core sample
firom the test patch to check the thickness of the coating (for a
building encapsulant or thickness of^on (for a
Penetrating encapsulant).
^Pplir^tion of Encapsulant
pressure of airless spray equipment is adjustable The
«orr®ct nozzle pressure varies from 400 to 1500 pounds per square
inch, depending'primarily on the encapsulant's viscosity and
s«condarily on its solids content. In general, the lower a
substance's viscosity and percentage of solids, the lower the
Pressures at which it can be sprayed- Since higher pressures
cause more asbestos fibers to be blown away from the surface, the
tncnas away. An appropriately sized tip will spray tne
encapsulant in a fan approximately eight inches" wide ?* it will
also distribute the encapsulant uniformly within the fan. An
improper tip will often concentrate the encapsulant at the fan's
Particularly on mors friable material, it is usually a good
practice to apply first a light mist coat of the encapsulant.
The purpose of this preliminary coat is to moisten and seal loose
fibers and keep them from breaking away from the surface. This
mist coat should be applied in threa or four quick passes with
the gun held IS to 24 inches from the surface."
After an area of 16 to 20 square feet has been given the mist
coat, the applicator can proceed immediately to apply a heavier
coating of the encapsulant, using eight or ten passes with the
gun held 10 to 12 inches from the material. The gun should be
kept in constant motion to create a smooth and even coat.
This two-step application is considered to be the first coat.
Host encapsulants should be applied in two or three separate
coats, with time allowed after each coat for the encapsulant to
cure. Note that the amount of drying time varies from
encapsulant to encapsulant, and that manufacturers'
recommendations should be followed. In general, penetrating
encapsulants should be allowed to cure for only about four hours
before the second coat is applied; if the first coat cures
completely, it will not allow the second coat to penetrate into
the material. Bridging encapsulants should be allowed to cure
for somewhat longer before another coat is added. Each
subsequent coat should be applied at a 90 degree angle to the
direction of the preceding coat application, to assure complete
coverage of tne asbestos-containing material.
is important not to apply too much encapsulant in each coat.
A penetrating encapsulant, if applied too thickly, can block the
surface of the material as it cures, preventing any subsequent
coats from penetrating into the material. Further, over-*
application of a penetrating encapsulant can cause the asbestos-
containing material to become too wet and to break loose _ from the
substrate. This second problem is also important for bridging
°ne method for preventing over-application is for the sprayer to
keep a mental note of the number of passes made with the spray
f^n. An experienced applicator will also be able to tell by
listening to the sound the encapsulant makes when u hits the
surface: when the material becomes saturated, there will be a
distinct sound change. Third, the changing color of the material
it is sealed can aive an indication of how much encapsulant
constitutes a coat (if a penetrating encapsulant is unpigraented,
food color 'no or a similar dye—not a pigment—can hm added to
3i*e it a slicht tint). Apolying a different color encapsulant
for „ch%*«9Sui M1P to ensure conplete covering.

Dilation also plays an important role in encapsulant
application. Some encapsulants must be diluted with water. Even
if dilution is not required/ it often makes it possible to apply
the encapsulant at a lower pressure to reduce the release of
fibers. Dilution may also improve the penetrating quality of the
encapsulant. Most manufacturers give recommendations concerning
dilution on the labels of their encapsulants. Some
experimentation will also help determine when dilution is useful.
Most manufacturers will provide on request a data sheet including
recommendations for tip size, spray pressure, number of coats to
be applied, drying time, and so forth. Contractors and other
interested parties are strongly advised to obtain this
One-coat coverage rates for most penetrating encapsulants range
from 10 to 40 square feet of friable asbestos—containing material
per gallon of encapsulant. Bridging encapsulants may yield
slightly higher coverage, with one gallon providing one—coat
coverage of 20 to 40 square feet. These figures are based on
Battelle's studies of encapsulants, and tend to be lower than
manufacturers may claim.
The coveraqe rate of a penetrating encapsulant is dependent
primarily on the thickness of the material to be encapsulated and
the ability of the encapsulant to wet the. material. The thicker
the material, the more encapsulant will be required to fill it
completely aid oenetrate to the substrate. Better penetrating
encapsulants often have lower coverage rates because they
Penetrate more deeply into the material.
Coveraae with bridging encapsulants is also affected by such
IriSf's »« tb« degree of their penetration and the texture of
-J£-";?Le Unsurprisingly/ the rate of coverage tends to b.
lower on irregular surfaces.
jjlgh Humidity Areas
late asbestos-containing material
£t is often difficult to encaps - already be damp and thus
U humid air, since the	encapsulant than if encapsulation
tend to absorb much less of jo This probiem can be caused
were performed under dry or ^y conditions within a
by the humidity of the ou
Asbestos Exposure Problems During Application of Encapsulants
Problems of worker exposure to asbestos< during encapsulation jobs
can usually be attributed to failure to" follow EPA and OSHA
regulations or guidelines: by attempting to encapsulate highly
friable material which should really be removed, by spraying
encapsulants at too high a pressure setting, or by holding the
spray gun too close to the surface. Any of these mistakes can
cause tne encapsulant spray to dislodge pieces of asbestos-
containing material into the air, resulting in serious problems
of worker exposure to airborne asbestos. Failure to follow EPA
and OSHA regulations and guidelines could also result in total
faiure of the encapsulation.
Exposure problems can also result from failure to observe EPA
recommendations for fiber containment during encapsulation
}obs. Consult Asbestos-Containing Materials in School
Buildings: A Guidance Document, and follow tnese recommendations
careruliy. Failure to do so can result in exposure of workers
and building users to hazardous levels of airborne asbestos, and
may subject the responsible party to punitive action by EPA or

This test, which has been adapted from the American Society for
Testing and Materials (ASTM) Standard Test Method E 736-80, has
been used extensively in some parts of the country.
This test indicates whether friable asbestos-containing materials
have sufficient adhesive and cohesive strength to sustain the
weight of an encapsulant.
1.	A cap, 3V4" in diameter and approximately V2" deep. A hook
shall be attached at the center.
2.	An adhesive system of urethane resin to form a rigid foam.
3.	A two pound weight.
1.	Select at random three locations on the asbestos-containing
material on which to perform the test. Then, at each
location, perform the following steps:
2.	Mix a.sufficient quantity of the urethane resin system in the
cap, and place the car immediately placed against the friable
asbestos-containing material being tested.
3.	Hold the cap in place until the resin- has completely foamed
and has set sufficiently to become self supporting.
4.	After the foam becomes hard, engage the weight carefully on
the hook. This applies a uniform force of 36 pounds, per
square foot perpendicular to the surface.
5.	The material must support the weight for one (1) minute at
each test location in order to pass tne-test.

Note: The adhered cap can be removed by carefully cutting the
foam away from the asbestos-containing material'with a sharp
knife or hacksaw blade, or it can be left in place for future
Interpretation of Results
If friable asbestos-containing material does not pass this test,
encapsulation is' probably not an appropriate method for
controlling fiber release.

P 622-538
P 95-C-104
B 95-W-IOO
3	iii	7 8 9 10 H
Pindley Adhesives Inc.	NA 25% 0.375 50 60 1% 10% 20	360
P.O. Box 3000
Elm Grove, WI 53122
M.A. Bruder & Sons,Inc.	300 25% 0.425 26 30 28% 14% 36	650
600 Reed HriL, P.O. Box 600
Broomall, PA 19008
M.A. Bruder & Sons, Inc.	9,600 69% 0.125 36 50 5% 47% 39	705
600 Reed Rd., P.O. Box 600
Broomall, PA 19008

1 2
B Thennatek
Ultra Ix>k 40-871
Protck Manufacturing
520 S. Muskego Ave.
Milwuakee, WI 53208
Therma-Cous t ics
P.O. Box 190
Col tori, CA 92324
Cellin Manufacturing, Inc.
P.O. Box 688
Sprirtgfield, VA 22150
lX>w Chemical Co.
P.O. Box 1847
2040 Dow Center
Midland, MI 48640
i i £ 2iii2.iL i!
53 41% 0.100 4 6 11* 1% 0	0
380 43% 0.250 6 8 4% 15% 22
8 48% 0.188 60 >60 2% 2% 18
28 30% 0.375 55 >60 8% 5% 25
Water-based XD-DG Dow Chemical Co.	475 24% 0.375 50 60 10% 0 20	360
(21-B)	P.O. Box 1847
2040 Dow Center
Midland, MI 48640
#207 Special Sealer	Makus Development Corp. 10 59% 0.500 60 >60 1% 9%	17298
(27-A)	P.O. Box 31
Mercer Island, WA 98040
25-2355	Nat'l £'£&,*.* and domical Corp.	35 *7% 0.300 6 10 8% 27% 16	290
(51-A)	1164 N. iireat Southwest Pkwy.
Grand Prairie, TX * 75050

B L241-43
Part A t> B
P Metro-shield
P Mono-therm F-100
P Penqua 200
B Product No. 1583
B Pyrokote-MX
P Super Cheinseal
Carboline Co.	NA NA 0.100 8 10 45% 38% 17	300
350 Hartley Industrial Court
St. Louis, MO 63144
Bertelson Associates, Inc.	10 29% 0.350 14 20 7% 53% 21	370
8 Del wood lane
Tinton Falls, NJ 07724
Mono-thenw Industries, Inc.	8 42% 0.250 52 60 2% 2% 13	230
10019 120th Ave. NE
Kirkland, WA 98033
United Coatings	24 26% 0.250 50 52 27% 9% 15	260
K. 1130 Sprague Ave.
Spokane, WA 99202
II.B. Fuller CO.	21,000 63% 0.080 10 14 42% 42% 21	300
Foster Division
P.O. Box 625
Springhouse, PA 19477
Development Services	NA NA 0.125 50 58 0% 0% 1	10
2021 K St. NW, Suite 305
Washington, DC 20006
Chemray Coatings Corp.	33 49% 0.500 10 14 20% 26% 16	290
150 Lincoln Blvd.
Middlesex. NJ 08846

P Aqualo id 15-10 Essex Chemical
(29-C)	125 Blackstone
Jamestown, NY
_4 5 6
Corporation	700 14% 0.250
7 8 9 10 11	12
50 60 1% 4% 22	395
P Chernex Ultra Seal Cheinex Chemical and Coating Co.,	8 15% 1.000 42 48 5% 2% 16	290
(12-B)	Chemical Division
P.O. Box 5072
Tampa, PL 33675
B C-1019
California Products Corp.
169 Waverly Street
Cambridge, MA 02139
4,600 49% 0.125 10 14 20%
Mateson Chemical Corp.
1025 Montgomery Ave. ,
Philadelphia, PA 19125
PIC Composites, Ltd.
1993 Leslie Street
Don Mills, Ontario M3B 2M3
100 18% 0.250 54 60 0% 1%
130 46% 0.150 14 16 7% 4%
B llygienscote	Acalor Chemical Construction	5,500 52% 0.125 20 26 48% 51% 28	500
(48-A)	33 Kerihar Drive
Weston, Ontario M9L 1M9

D Ocean 666
SK-13 Emulsion
P 32-20 and 32-21
Flaine-Crete Co. of Canada
1072 Cyrville Road
Ottawa, Ontario KIJ 7S5
Habersham Industries, Inc.
5212 Irvdustrial Court
Smyrna, GA 30000
National Cellulose Corp.
P.O. Box 45006
12315 Robin Boulevard
Houston, TX 77045
II. B. Fuller Co.
Foster Products Division
P.O. Box 625
Springhouse, PA 19477
±56	7 8 9 10 11
3,600 42% 0.100 14 16 30% 44% 18
13 8% 0.625 58 >60 5% 3% 6
28 45% 0.500 50 60 0% 0% 13
5 10% 0.875 50 60 3% 3% 2

i-ncapsuu- axjnd 10 i£ Kccmm& oh m iv&is a? baiitelik's iaqoratory tests
12	2	A i£2£ii0JA!l
P Asbestite 2000 Arpin Products, Inc.	8 21% 1.000 46 60 5% 5% 2	25
(35-A)	P.O. Box 262
Qakhurst, NJ 07755
P Asbestop I3W225 McGeddy International, Inc.	10 22% 0.500 50 60 2% 2% 17	310
(30-B)	1043 Broadway
W. Long Branch, NJ 07764
B Cable Coating 2-B American Coatings Corp.	180 64% 0.188 52 60 40% 48% 17	295
(35-Li)	5235 N. Elston
Chicago, IL 60630
I* Cafco-Bond-Seal U.S. Mineral Products Co.	10 12% 0.750 46 60 3% NA 5	80
(19-A)	Stanhope, NJ 07874
B Decadex Firecheck Pentagon Plastics, Ltd.	52,000 68% 0.125 60 >60 33% NA 16	290
(4-A)	905 N. Railroad Avenue
W. Palm Beach, PL 33401
B EX-64-2	Lehman Brothers Corp.	6,250 56% 0.156 60 >60 15% 22% 20	355
(13-B-3)	22 llalladay St.
Jersey City, NJ 07304
the resultant smoke was measured in the same manner as
in the test described in #9.
11)	shows the flame spread index of the encapsulanted test
matrix as determined by Battelle in a test based on
ASTM method E 162. A high flame spread index
indicates a lower fire resistance classification; the
scale runs from 0 to 200,. with an index of less than
26 yielding a fire rating of Class "A" and an index^
between 26 + 75 yielding a fire rating of Class "3."
12)	shows the heat evolved from the test matrix in
Battelle's tests for encapsulant flammability,
measured in British thermal units per minute per
square foot during the test described in $11.
The requirements for a rating of "acceptable" are as follows:
1.	A Class "A" fire resistance rating (i.e., a flame spread
index of 25 or less); see column 11.
2.	A maximum of 50% capacity resulting from smoke generation
in the flame smoke generation test, and a maximum of 50%
capacity resulting from smoke generation in the glow—wire
smoke generation test; see columns 9 and 10.
3.	Toxic gas release on burning less than the "possible
problem" levels set by the National Academy of Sciences.
All products which appear on this list had toxic gas
releases well below NAS' s "possible problem" levels.
4.	Good surface integrity capable either of sealing the
fibrous surface (as a bridging encapsulant) or of bidding
the fibers together by penetrating 0.5 inches or more into
the test matrix (as a penetrating encapsulant).
Given the fact that Battelle1s tests were run only once on
each encapsulant and are subject, like any test, to statistical
error, products which were within 20% of "acceptability"
according to each of these requirements were rated as "marginally
It snould be stressed again that Battelle's tests were
conducted on a mineral wool matrix which did not contain
asbestos, and that the results of these tests will not
necessarily duplicate the results achieved when an encapsulant is
applied to an asbestos-containing material.

not necessarily imply that that product is an unsatisfactory
The table is divided into twelve columns; a brief explanation
of each column is given below.
1)	indicates whether the encapsulant was classified 'oy
Battelle as a bridging encapsulant (B) or a
penetrating encapsulant (P).
2)	shows the brand name of the encapsulant. The number
in parentheses after the name is the code number given
to the encapsulant by Battelle.
3)	shows the name, address, and telephone number of the
encapsulant's manufacturer.
4)	shows the viscosity of the encapsulant in centipoises
as measured by Battelle.
5)	shows the encapsulant's percent solid content by
weight as determined by Battelle.
6)	shows the penetration in inches achieved by the
encapsulant when it was applied by airless spray to
the mineral wool test matrix.
7) and 8) show the minimum and maximum impact resistance of the
encapsulated test matrix, measured in inch—oounds•
For this test, the sample holder and anvil were
removed from a Gardner impact tester, and a small
block of encapsulated mineral wool was placed directly
under the dropping load. The figures in columns 7 and
8 show the minimum amd maximum number of inch—pounds
required to penetrate 0.5 inches into the encapsulated
test block.
9)	indicates the amount of smoke generated when the
encapsulated matrix was subjected to an open flame.
In this test, a flame of approximately 1500° F was
applied to the lower edge of a specimen of
encapsulated mineral wool for ten ininutes. The
density of the resultant smoke was measured with a
General Electric CR7505 Smoke Density Indicator. The
number given in the table shows the percent opacity
caused by the smoke which the burning test matrix
generated; the higher the percentage the greater the
generation of smoke.
10)	also indicates the amount of smoke generated by a
specimen of the encapsulated mineral wool. In this
test, however, a heated electrical coil of
approximately 1000® F, rather than an open flame, was
applied to the sample for ten minutes. The density of

Battelle Columbus Laboratories, under contract from the U.S.
Environmental Protection Agency (EPA), has evaluated 100
commercially available encapsulants for friable asbestos-
containing materials in buildings. Manufacturers of encapsulants
were invited to submit their products to Battelle in an
advertisement placed in the Commerce Business Daily on February
10 , 1978.		!	
To test the encapsulants, Battelle used a mineral wool
insulation material which was spray-applied to plywood. This
mineral wool insulation was designed to simulate friable
asbestos-containing insulation material. Sections of the
materials were mounted on an overhead panel, and a different
encapsulant was applied to each section. Each encapsulant was
applied in three coats by airless spray.
Since the material on which the encapsulants were tested did
not actually contain asbestos, the results of the tests should
not be interpreted as indicating the probable results if the
encapsulants were applied to asbestos-containing insulation.
Rather, the tests were designed to indicate the relative quality
of the various products.
On the basis of its laboratory tests, Battelle judged eleven
of the 100 encapsulants to be "acceptable," and rated twenty-'
three others "marginally acceptable." These terms should not be
construed to imply that the use of any of the encapsulants is
acceptable or advisable in a given situation. Whether a given
encapsulant, or any encapsulant, is appropriate in a given
situation depends on a number of variables, many of which are
beyond the scope of Battelle's study.
This tab!-? shows certain information about the thirty-four
encaosulants nudged by Battelle to be "acceptable" or "marginally
acceptable" «. "« the basis of its laboratory tests. The
jiformation here was taXen from Battelle s Draft cinal Report on
Evaluation of Encapsulants for Sprayed-On Asbestos-Containing
Materials in Buildings," as revised at meetings between Battelle
and EPA personnel on June 3, 1981.
This table has not been reviewed or approved by the United
States Environmental Protection Agency and should not, thererore,
be construed as a reflection of EPA-policy. The inclusion
Jtncapsulant in this table may also not be construe as an
r -rrr—s.nflte—pg-odiicl*. 3ither by 3at*elle or y i	*
.i5£/a: given product rrom this Us.- does
. sv: •• ^	jft.
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