ASTM C581-03(2008)e1
(Practice)Standard Practice for Determining Chemical Resistance of Thermosetting Resins Used in Glass-Fiber-Reinforced Structures Intended for Liquid Service
Standard Practice for Determining Chemical Resistance of Thermosetting Resins Used in Glass-Fiber-Reinforced Structures Intended for Liquid Service
SIGNIFICANCE AND USE
The results obtained by this practice shall serve as a guide in, but not as the sole basis for, selection of a thermosetting resin used in an RTP structure. No attempt has been made to incorporate into the practice all the various factors that may enter into the serviceability of an RTP structure when subjected to chemical environments. These factors may include stress, different resin-to-glass ratios, and multiple veils.
SCOPE
1.1 This practice is designed to evaluate, in an unstressed state, the chemical resistance of thermosetting resins used in the fabrication of reinforced thermosetting plastic (RTP) laminates. This practice provides for the determination of changes in the properties, described as follows, of the test specimens and test reagent after exposure of the specimens to the reagent: hardness of specimens, weight change thickness, appearance of specimens, appearance of immersion media, and flexural strength and modulus.
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
Note 1—This practice may also be used to evaluate other factors, such as surfacing veils, the effect of resin additives, and fabrication variables on the chemical resistance of the resin.
Note 2—There is no known ISO equivalent to this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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´1
Designation: C581 − 03(Reapproved 2008) An American National Standard
Standard Practice for
Determining Chemical Resistance of Thermosetting Resins
Used in Glass-Fiber-Reinforced Structures Intended for
Liquid Service
This standard is issued under the fixed designation C581; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
ε NOTE—Note 2 was editorially revised in August 2008.
1. Scope and Reinforced Plastics and Electrical Insulating Materi-
als
1.1 This practice is designed to evaluate, in an unstressed
D2563 Practice for Classifying Visual Defects in Glass-
state, the chemical resistance of thermosetting resins used in
Reinforced Plastic Laminate Parts
the fabrication of reinforced thermosetting plastic (RTP) lami-
D2583 Test Method for Indentation Hardness of Rigid Plas-
nates. This practice provides for the determination of changes
tics by Means of a Barcol Impressor
in the properties, described as follows, of the test specimens
D2584 Test Method for Ignition Loss of Cured Reinforced
and test reagent after exposure of the specimens to the reagent:
Resins
hardnessofspecimens,weightchangethickness,appearanceof
specimens, appearance of immersion media, and flexural
3. Significance and Use
strength and modulus.
3.1 The results obtained by this practice shall serve as a
1.2 The values stated in inch-pound units are to be regarded
guide in, but not as the sole basis for, selection of a thermo-
as standard. The values given in parentheses are mathematical
setting resin used in an RTP structure. No attempt has been
conversions to SI units that are provided for information only
madetoincorporateintothepracticeallthevariousfactorsthat
and are not considered standard.
may enter into the serviceability of an RTP structure when
subjectedtochemicalenvironments.Thesefactorsmayinclude
NOTE 1—This practice may also be used to evaluate other factors, such
assurfacingveils,theeffectofresinadditives,andfabricationvariableson stress, different resin-to-glass ratios, and multiple veils.
the chemical resistance of the resin.
4. Apparatus
NOTE 2—There is no known ISO equivalent to this standard.
1.3 This standard does not purport to address all of the
4.1 HardnessTestingInstrument—Thisshallbeasdescribed
safety concerns, if any, associated with its use. It is the
in Test Method D2583.
responsibility of the user of this standard to establish appro-
4.2 Flexural Properties Testing Apparatus, in accordance
priate safety and health practices and determine the applica-
with Test Methods D790.
bility of regulatory limitations prior to use.
4.3 Thickness Measurement—A micrometer suitable for
measurement to 0.001 in. (0.025 mm).
2. Referenced Documents
4.4 Containers, of sufficient size, capacity, and inertness to
2.1 ASTM Standards:
allow total immersion of reinforced thermosetting plastic
D790 Test Methods for Flexural Properties of Unreinforced
specimens in the specific corrosives chosen for testing. These
containers shall, when necessary, be capable of maintaining
liquid levels of volatile solutions, that is, solvents. This can be
ThispracticeisunderthejurisdictionofASTMCommitteeD20onPlasticsand
accomplished by the use of reflux condensers.
is the direct responsibility of Subcommittee D20.23 on Reinforced Plastic Piping
Systems and Chemical Equipment.
4.5 HeatingApparatus—Aconstant temperature oven, heat-
Current edition approved May 1, 2008. Published August 2008. Originally
ing mantle, or liquid bath capable of maintaining temperature
approved in 1965. Last previous edition approved in 2003 as C581 – 03. DOI:
within range of 64.0°F (62.2°C). Proper precautions should
10.1520/C0581-03R08E01.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or be taken if the corrosives selected are flammable liquids.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
4.6 Analytical Balance, suitable for accurate weighing to
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 0.001 g.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
C581 − 03 (2008)
5. Reagents significantly lower hardness values. The hardness value will
vary with the type of resin and number of plies of synthetic
5.1 The test media shall consist of the reagents or solutions
veil. The resin manufacturer should be contacted for the
to which the RTP laminates are to be exposed.
allowable Barcol hardness value of a laminate containing
synthetic veils with the specific resin.
6. Test Specimens
6.2.5 Laminate Condition—The laminate shall meetAccep-
6.1 Standard Laminates—Prepare standard fiber-reinforced
tance Level I of Table I of Practice D2563.
laminates using identical reinforcement in all of the laminates.
The laminates shall be constructed of the following materials:
6.3 Fabrication of Standard Laminate—The sequence of
6.1.1 Surfacing Mat (Veil)—A thin mat of fine fibers used lay-up shall be as follows:
primarily to produce a smooth, resin-rich surface on a rein-
6.3.1 Apply catalyzed resin and a 10-mil (0.25-mm) surfac-
forced plastic.The surfacing veil helps determine the thickness
ing mat on a flat surface covered with plastic release film or
of the resin-rich layer, reduces microcracking and provides a
treated with a suitable release agent and roll to distribute resin.
non-wicking chemically–resistant layer. The surfacing veil
NOTE 4—The following formula may be used as a guide to determine
shall be compatible with the resin, and manufactured with
the total weight of resin to be used. This is equivalent to 12.5 volume %
uniform fiber distribution and non-bundled fibers. The dry veil
glass fiber in the laminate. Grams resin equals grams glass fiber material
layer(s) shall be a minimum 10 mils in thickness and produce
per 6.2.3 times 2.82 G. Where G equals specific gravity of cured resin.
Excess resin may be used due to loss by adhering to mixing containers,
a 10 to 15 mil resin-saturated veil layer per 10 mils of dry veil.
rollers,andotherfactors.Asuggestedamountofexcessresinis10to15 %
To eliminate the surfacing veil as a variable in corrosion tests,
by weight.
prepare each laminate within a test group with the same
surfacing veil. 6.3.2 Follow with three plies of 1.5 oz/ft chopped strand
6.1.2 Chopped Strand Mat—Type E glass fiber with sizing mat and resin. Roll after each ply to distribute and wet-out the
and binder compatible with the resin. Other glass fiber com- chopped strand mat. Rolling with a serrated roller may be done
positionsmaybeusedbutshouldbeconsideredasvariablesfor
after each ply to remove entrapped air but shall be done in
comparison to the standard. accordancewith6.3.4.Thematweightshallbewithin 65%of
6.1.3 Resin—Catalyzed and promoted in accordance with 1.5 oz/ft upon weighing the full 26 by 33-in. cut (660 by
the resin manufacturer’s recommendation. 838-mm) piece, (or other full dimension used, 6.2.1.).
NOTE3—Fillers,suchasantimonytrioxideforimprovedfireretardancy
NOTE5—Choppedstrandmatshouldbecutsothatthe26-in.dimension
or thixotropes for viscosity control, may be added, but may detract from
is across the width of the roll and the 33-in. dimension is along the
the corrosion resistance of the test laminate.
machine direction of the mat. Mat weight variation will most commonly
occur across the width of the mat. If a wide roll of mat, 52 in. (1320 mm)
6.2 Dimensions and General Properties—The laminates
or greater, is used, the two plies of mat should be placed in the laminate
shall conform to the required dimensions and general proper-
such that the center cut of one ply is placed over the outside edge of the
ties of 6.2 and be fabricated in accordance with 6.3.
second ply. If narrower width mat is used, the second ply should be
6.2.1 Laminate Size—A suitable laminate size has been reversed 180° in the machine direction and laid on top of the first ply to
minimize weight variations.
found to be 26 by 33 in. (660 by 838 mm) after trimming. This
laminate size is not restrictive and other dimensions may be
6.3.3 Follow with a 10-mil (0.25-mm) surfacing mat as in
used.
6.3.1.
6.2.2 Thickness—The thickness of the cured standard lami-
6.3.4 Remove the air by rolling over the surface with a
nate shall be between 0.120 and 0.140 in. (3.05 and 3.56 mm).
serrated metal or plastic roller. Take care not to expel enough
6.2.3 Reinforcement Content—The glass fiber and binder
resin to raise the glass content above the permissible maxi-
2 2
shall be 4.73 6 0.47 oz/ft (three layers of 1.5 oz/ft chopped
mum.The laminate is considered within the range of allowable
strand mat 4.5 oz/ft having a nominal binder content of 3.5 %
levels of resin and glass if the thickness of the laminate is
and two layers of 10 mil surfacing mat 0.23 oz/ft having a
within 0.120 and 0.140 in. (3.05 and 3.56 mm), as described in
nominal binder content of 7 %)—determined by preweighing
6.2.2.
the materials prior to construction of the laminate. This is
6.3.5 After the lay-up is completed, cover the laminate with
equivalent to 23.6 weight % (12.5 volume %) glass fiber when
a plastic release film to prevent air inhibition or to provide a
using a resin having a cured specific gravity of 1.15. Such a
uniform smooth glossy surface, or both. Carefully smooth
laminate will have a thickness of 0.125 in. (3.18 mm). The use
down to remove entrapped air.
of resins having different specific gravities will result in
NOTE 6—The application of the release film may be accomplished by
different weight percentages of glass fiber, but the volume
any convenient method. Regardless of how it is applied, it is critical that
percentage of glass fiber will remain the same. When using
any entrapped air between the film and the laminate be entirely removed.
synthetic organic fiber surfacing veil, the glass content shall be
Onemethodofapplicationisdonebypreviouslywrappingthefilmaround
2 2
4.50 6 0.45 oz/ft ( three layers of 1.5oz/ft chopped strand
a metal rod. Starting at one edge of the laminate, slowly unroll the film
mat having a nominal binder content of 3.5 %). from the rod, keeping a bead of resin ahead of the rod as you cross the
laminate. Any entrapped air remaining can be removed by rubbing a
6.2.4 Hardness—The hardness shall be at least 90 % of that
tongue depressor across the release film surface. Carefully pull the film
of a fully-cured clear casting of the resin, or of a similarly
taut and fasten at the edges to prevent wrinkling of the film. Placing stops
constructed laminate as defined by the resin manufacturer.
(neoprene has been found to be suitable) around the edges of the laminate
Hardness shall be determined in accordance with s4.1.It
and passing a heavy metal roller over the laminate helps to insure uniform
should be noted that the use of synthetic veil will result in controlled thickness.
´1
C581 − 03 (2008)
6.3.6 Cure as recommended by the resin manufacturer. The 7.2.1 Discard the test solution and replace it with fresh
cure schedule shall be reported. solution as often as necessary to maintain original composition
andconcentration.Asaminimum,solutionsknowntobestable
6.3.7 Trim edges as required.
should be replaced at the end of each test period.
6.4 RecordofStandardLaminateConstruction—Record the
7.3 Cleaning and Examination After Exposure—Clean the
properties of the standard laminate as follows:
coupon and dry by blotting with a paper towel. Cold tap water
6.4.1 Hardness—Determine Barcol hardness on the strip as
is normally used for specimen cleaning. If other cleaning
described in 6.2.4 in accordance with Test Method D2583.
agents are used, verify that they do not attack the resin being
6.4.2 Laminate Conditions—Visually examine the laminate.
tested.
The laminate shall meet Acceptance Level I of Table 1 of
7.3.1 Note any indication of surface attack on a coupon, any
Practice D2563.
discoloration of the test solution, and the formation of any
6.4.3 If the laminate meets the requirements of this
sediment.
specification,retainthelaminatesectionsforpreparationoftest
7.3.2 After final blotting, immediately measure the coupon
specimens.
thickness to the nearest 0.001 in. (0.025 mm) in the geometric
NOTE 7—The major criteria for accepting a laminate is thickness and
center of each intended 1 by 3 in. (25 by 76.2 mm) specimen.
not glass content. If glass content is desired, cut eight 1 by 1 in. specimens
Measure the coupon to the nearest 0.01g. The Barcol hardness
from the center of the laminate and test in accordance with Test Method
can then be checked, taking an average of ten readings on each
D2584.
coupon, a minimum of 0.50 in. (12.7 mm) from the edge.
6.5 Individual Test Specimens:
7.3.3 After washing and measuring thickness, weight, and
6.5.1 Specimens for immersion in test solutions shall be
Barcol hardness, place the coupons in an air-tight polyethylene
approximately 4 by 5 in. (101.6 by 127 mm), cut from the
bag for conditioning or shipping as described in 7.4.1.
standard laminate.
7.4 Flexural Testing—Determine the flexural strength and
6.5.2 Identity of specimens shall be maintained by suitable
modulus for: (1) two sets of three specimens immediately
means.
following the curing period, and (2) one set of three specimens
6.5.3 Cut edges and drilled holes, if used for suspension,
after each inspection, for each solution, and each test tempera-
shall be sanded smooth and coated with paraffinated resin.
ture. Calculation of flexural strength and modulus after expo-
6.5.4 Thenumberofspecimensrequiredisdependentonthe
sure should use the coupon thickness determined at the time of
number of test solutions to be employed, the number of
flexural testing as measured in 7.3.2. The two pretested sets
different temperatures at which testing is performed, and the
shall be taken from the center of the laminate as described in
number of test intervals. In addition, at least two 4 by 5 in.
6.2.1. The flexural strengths for these two sets shall be
(101.6 by 127 mm) specimens shall be available for test (see
averaged together for use in calculating the retained flexural
7.4) following the curing period, prior to immersion.
strength in 8.2. The flexural modulus values shall also be
averaged for use in 8.2.
7. Procedure
7.4.1 Flexural tests shall be conducted in accordance with
7.1 Measurement of Specimens—Immediately following the
ProcedureAofTestMethodsD790,exceptfortheconditioning
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
An American National Standard
´1
Designation:C 581–00 Designation: C 581 – 03 (Reapproved 2008)
Standard Practice for
Determining Chemical Resistance of Thermosetting Resins
Used in Glass-Fiber-Reinforced Structures Intended for
Liquid Service
This standard is issued under the fixed designation C 581; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
´ NOTE—Note 2 was editorially revised in August 2008.
1. Scope
1.1 This practice is designed to evaluate, in an unstressed state, the chemical resistance of thermosetting resins used in the
fabrication of reinforced thermosetting plastic (RTP) laminates. This practice provides for the determination of changes in the
properties, described as follows, of the test specimens and test reagent after exposure of the specimens to the reagent: hardness
of specimens, weight change thickness, appearance of specimens, appearance of immersion media, and flexural strength and
modulus.
1.2The values stated in inch-pound units are to be regarded as the standard. The values in parentheses are given for information
only.
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
NOTE 1—This practice may also be used to evaluate other factors, such as surfacing veils, the effect of resin additives, and fabrication variables on
the chemical resistance of the resin.
NOTE2—There is no similar or equivalent ISO standard. 2—There is no known ISO equivalent to this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
D 790 Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials
D 2563 Practice for Classifying Visual Defects in Glass-Reinforced Plastic Laminate Parts
D 2583 Test Method for Indentation Hardness of Rigid Plastics by Means of a Barcol Impressor
D 2584 Test Method for Ignition Loss of Cured Reinforced Resins
3. Significance and Use
3.1 The results obtained by this practice shall serve as a guide in, but not as the sole basis for, selection of a thermosetting resin
used in an RTP structure. No attempt has been made to incorporate into the practice all the various factors that may enter into the
serviceability of an RTP structure when subjected to chemical environments. These factors may include stress, different
resin-to-glass ratios, and multiple veils.
4. Apparatus
4.1 Hardness Testing Instrument—This shall be as described in Test Method D 2583.
4.2 Flexural Properties Testing Apparatus, in accordance with Test Methods D 790.
4.3 Thickness Measurement—A micrometer suitable for measurement to 0.001 in. (0.025 mm).
ThispracticeisunderthejurisdictionofASTMCommitteeD20onPlasticsandisthedirectresponsibilityofSubcommitteeD20.23onReinforcedPlasticPipingSystems
and Chemical Equipment.
Current edition approved July 10, 2000. Published September 2000. Originally published as C581–65T. Last previous edition C581–94.
Current edition approved May 1, 2008. Published August 2008. Originally approved in 1965. Last previous edition approved in 2003 as C 581 – 03.
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. ForAnnualBookofASTMStandards
, Vol 08.01.volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
´1
C 581 – 03 (2008)
4.4 Containers, of sufficient size, capacity, and inertness to allow total immersion of reinforced thermosetting plastic specimens
in the specific corrosives chosen for testing. These containers shall, when necessary, be capable of maintaining liquid levels of
volatile solutions, that is, solvents. This can be accomplished by the use of reflux condensers.
4.5 HeatingApparatus—Aconstant temperature oven, heating mantle, or liquid bath capable of maintaining temperature within
range of 64.0°F (62.2°C). Proper precautions should be taken if the corrosives selected are flammable liquids.
4.6 Analytical Balance, suitable for accurate weighing to 0.001 g.
5. Reagents
5.1 The test media shall consist of the reagents or solutions to which the RTP laminates are to be exposed.
6. Test Specimens
6.1 Standard Laminates—Prepare standard fiber-reinforced laminates using identical reinforcement in all of the laminates. The
laminates shall be constructed of the following materials:
6.1.1 Surfacing Mat (Veil)—A thin mat of fine fibers used primarily to produce a smooth, resin-rich surface on a reinforced
plastic.The surfacing veil helps determine the thickness of the resin-rich layer, reduces microcracking and provides a non-wicking
chemically–resistant layer. The surfacing veil shall be compatible with the resin, and manufactured with uniform fiber distribution
and non-bundled fibers. The dry veil layer(s) shall be a minimum 10 mils in thickness and produce a 10 to 15 mil resin-saturated
veil layer per 10 mils of dry veil. To eliminate the surfacing veil as a variable in corrosion tests, prepare each laminate within a
test group with the same surfacing veil.
6.1.2 ChoppedStrandMat—Type E glass fiber with sizing and binder compatible with the resin. Other glass fiber compositions
may be used but should be considered as variables for comparison to the standard.
6.1.3 Resin—Catalyzed and promoted in accordance with the resin manufacturer’s recommendation.
NOTE 3—Fillers, such as antimony trioxide for improved fire retardancy or thixotropes for viscosity control, may be added, but may detract from the
corrosion resistance of the test laminate.
6.2 DimensionsandGeneralProperties—The laminates shall conform to the required dimensions and general properties of 6.2
and be fabricated in accordance with 6.3.
6.2.1 LaminateSize—Asuitable laminate size has been found to be 26 by 33 in. (660 by 838 mm) after trimming.This laminate
size is not restrictive and other dimensions may be used.
6.2.2 Thickness—The thickness of the cured standard laminate shall be between 0.1300.120 and 0.140 in. (3.30(3.05 and
4.403.56 mm).
2 2
6.2.3 ReinforcementContent—Theglassfiberandbindershallbe0.9454.73 60.090.47oz/ft (threelayersof1.5oz/ft chopped
chopped strand mat 4.5 oz/ft
strand mat–0.591 oz/ft having a nominal binder content of 3.5 % and two layers of 10 mil surfacing
mat–0.044mat0.23oz/ft havinganominalbindercontentof7 %)—determinedbypreweighingthematerialspriortoconstruction
of the laminate.This is equivalent to 23.6 weight % (12.5 volume %) glass fiber when using a resin having a cured specific gravity
of1.15.Suchalaminatewillhaveathicknessof0.125in.(3.18mm).Theuseofresinshavingdifferentspecificgravitieswillresult
in different weight percentages of glass fiber, but the volume percentage of glass fiber will remain the same. When using synthetic
organic fiber surfacing veil, the glass content shall be 0.885 oz/ft ( three layers of 1.5oz/ft. chopped strand mat. (two layers of
2 2
1.54.50 6 0.45 oz/ft ( three layers of 1.5oz/ft chopped strand mat having a nominal binder content of 3.5 %).
6.2.4 Hardness—The hardness shall be at least 90 % of that of a fully-cured clear casting of the resin, or of a similarly
constructedlaminateasdefinedbytheresinmanufacturer.Hardnessshallbedeterminedinaccordancewiths4.1.Itshouldbenoted
that the use of synthetic veil will result in significantly lower hardness values. The hardness value will vary with the type of resin
and number of plies of synthetic veil. The resin manufacturer should be contacted for the allowable Barcol hardness value of a
laminate containing synthetic veils with the specific resin.
6.2.5 Laminate Condition—The laminate shall meet Acceptance Level I of Table I of Practice D 2563.
6.3 Fabrication of Standard Laminate— The sequence of lay-up shall be as follows:
6.3.1 Apply catalyzed resin and a 10-mil (0.25-mm) surfacing mat on a flat surface covered with plastic release film or treated
with a suitable release agent and roll to distribute resin.
NOTE 4—The following formula may be used as a guide to determine the total weight of resin to be used. This is equivalent to 12.5 volume % glass
fiber in the laminate. Grams resin equals grams glass fiber material per 6.2.3 times 2.82 G. Where G equals specific gravity of cured resin. Excess resin
may be used due to loss by adhering to mixing containers, rollers, and other factors. A suggested amount of excess resin is 10 to 15 % by weight.
6.3.2 Followwiththreepliesof1.5oz/ft choppedstrandmatandresin.Rollaftereachplytodistributeandwet-outthechopped
strand mat. Rolling with a serrated roller may be done after each ply to remove entrapped air but shall be done in accordance with
6.3.4.The mat weight shall be within 65 % of 1.5 oz/ft upon weighing the full 26 by 33-in. cut (660 by 838-mm) piece, (or other
full dimension used, 6.2.1.).
NOTE 5—Chopped strand mat should be cut so that the 26-in. dimension is across the width of the roll and the 33-in. dimension is along the machine
direction of the mat. Mat weight variation will most commonly occur across the width of the mat. If a wide roll of mat, 52 in. (1320 mm) or greater,
is used, the two plies of mat should be placed in the laminate such that the center cut of one ply is placed over the outside edge of the second ply. If
narrower width mat is used, the second ply should be reversed 180° in the machine direction and laid on top of the first ply to minimize weight variations.
´1
C 581 – 03 (2008)
6.3.3 Follow with a 10-mil (0.25-mm) surfacing mat as in 6.3.1.
6.3.4 Remove the air by rolling over the surface with a serrated metal or plastic roller. Take care not to expel enough resin to
raise the glass content above the permissible maximum. The laminate is considered within the range of allowable levels of resin
and glass if the thickness of the laminate is within 0.120 and 0.130 in.,0.140 in. (3.05 and 3.56 mm), as described in 6.2.2.
6.3.5 Afterthelay-upiscompleted,coverthelaminatewithaplasticreleasefilmtopreventairinhibitionortoprovideauniform
smooth glossy surface, or both. Carefully smooth down to remove entrapped air.
NOTE 6—The application of the release film may be accomplished by any convenient method. Regardless of how it is applied, it is critical that any
entrapped air between the film and the laminate be entirely removed. One method of application is done by previously wrapping the film around a metal
rod. Starting at one edge of the laminate, slowly unroll the film from the rod, keeping a bead of resin ahead of the rod as you cross the laminate. Any
entrapped air remaining can be removed by rubbing a tongue depressor across the release film surface. Carefully pull the film taut and fasten at the edges
to prevent wrinkling of the film. Placing stops (neoprene has been found to be suitable) around the edges of the laminate and passing a heavy metal roller
over the laminate helps to insure uniform controlled thickness.
6.3.6 Cure as recommended by the resin manufacturer. The cure schedule shall be reported.
6.3.7 Trim edges as required.
6.4 Record of Standard Laminate Construction—Record the properties of the standard laminate as follows:
6.4.1 Hardness—Determine Barcol hardness on the strip as described in 6.2.4 in accordance with Test Method D 2583.
6.4.2 Laminate Conditions—Visually examine the laminate. The laminate shall meetAcceptance Level I of Table 1 of Practice
D 2563.
6.4.3 If the laminate meets the requirements of this specification, retain the laminate sections for preparation of test specimens.
NOTE 7—The major criteria for accepting a laminate is thickness and not glass content. If glass content is desired, cut eight 1 by 1 in. specimens from
the center of the laminate and test in accordance with Test Method D 2584.
6.5 Individual Test Specimens:
6.5.1 Specimens for immersion in test solutions shall be approximately 4 by 5 in. (101.6 by 127 mm), cut from the standard
laminate.
6.5.2 Identity of specimens shall be maintained by suitable means.
6.5.3 Cut edges and drilled holes, if used for suspension, shall be sanded smooth and coated with paraffinated resin.
6.5.4 The number of specimens required is dependent on the number of test solutions to be employed, the number of different
temperatures at which testing is performed, and the number of test intervals. In addition, at least two 4 by 5 in. (101.6 by 127 mm)
specimens shall be available for test (see 7.4) following the curing period, prior to immersion.
7. Procedure
7.1 Measurement of Specimens—Immediately following the curing period, measure the thickness of the specimens to the
nearest 0.001 in. (0.025 mm) at the geometric center of each of the intended 1 by 3 in. (25.4 by 76.2 mm) specimens that will be
cut for flexural tests after the completed exposures. Measure the weight of the specimens to the nearest 0.01 g. These thickness
and weight measurements shall also be used for comparison against thickness and weight measurements after the completed
exposures.
7.2 Exposure—Following the curing period, as specified in 6.3.6, prior to immersion, record a brief description of the color and
surface appearance of the coupons and the color and the clarity of the test solution. The total number of coupons per container is
not limited except by the ability of the container to hold the coupons without touching each other or the container. The coupons
must always be completely immersed. Coupons should be vertical, parallel, and spaced a minimum of 0.25 in. (6.35 mm) apart.
There should be a minimum of 0.50 in. (12.7 mm) between coupon edges and the container or the liquid surface. Place the closed
container in a constant temperature oven adjusted to the required temperature or in a suitably adjusted liquid bath. Examine the
coupons a
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