ASTM D7786-13(2019)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D7786 − 13 (Reapproved 2019)
Standard Test Method for
Determining Enamel Holdout
This standard is issued under the fixed designation D7786; 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.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This standard provides a method for determining the
D523 Test Method for Specular Gloss
holdout characteristics of a primer and topcoat coating appli-
D823 Practices for Producing Films of Uniform Thickness
cation. A standard topcoat is used to determine the absorption
of Paint, Coatings and Related Products on Test Panels
characteristics of a primer. Enamel holdout can be measured as
D1640 Test Methods for Drying, Curing, or Film Formation
a difference in observed gloss of the topcoat over a primer,
of Organic Coatings
relative to the gloss of the same topcoat over a non-porous,
E177 Practice for Use of the Terms Precision and Bias in
smooth surface.
ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to
1.2 The standard is written in the context that the user will
Determine the Precision of a Test Method
be evaluating the enamel holdout characteristics of a primer.
Alternatively,thestandardmaybeusedasamethodtoevaluate
3. Terminology
the enamel holdout characteristics of primer/topcoat system
3.1 Definitions:
where the primer is constant and different topcoats are used as
3.1.1 enamel holdout, n—the ability of a primer/topcoat
test paints.
system to retain gloss of the topcoat relative to gloss of the
1.3 This standard may also be used for evaluation of paints topcoat over a non-porous, smooth surface.
other than primers as the first coat. In this alteration the user
3.1.2 primer, n—an undercoat of paint applied to prepare a
can test the enamel holdout characteristics of a self-primed
surface for final painting.
topcoat,oruseofanyothertypeofpaintastheprimerfollowed
3.1.3 topcoat, n—a coating, intended as the final coat of a
by the use of a standard topcoat.
finished system, which has the desired appearance and resis-
tance properties as specified by the end user.
1.4 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
4. Summary of Test Method
standard.
4.1 Asubstrate, preferably a non-porous, smooth drawdown
1.5 This standard does not purport to address all of the
card, is coated using a test primer and allowed to dry. The
safety concerns, if any, associated with its use. It is the primer-coated substrate is then coated with the standard top-
responsibility of the user of this standard to establish appro- coat and allowed to dry (primed topcoat).
priate safety, health, and environmental practices and deter-
4.2 Anon-porous, smooth substrate is coated using only the
mine the applicability of regulatory limitations prior to use.
standard topcoat and allowed to dry (unprimed topcoat).
1.6 This international standard was developed in accor-
4.3 Gloss measurements are taken over the primed topcoat
dance with internationally recognized principles on standard-
and also over the unprimed topcoat. The difference in the gloss
ization established in the Decision on Principles for the
reading between the primed topcoat system and unprimed
Development of International Standards, Guides and Recom-
topcoat system is an indication of enamel holdout. Smaller
mendations issued by the World Trade Organization Technical
differences indicate better enamel holdout.
Barriers to Trade (TBT) Committee.
5. Significance and Use
5.1 This standard may be used by paint companies and raw
material suppliers to assess the interactions of primers and
This test method is under the jurisdiction of ASTM Committee D01 on Paint
and Related Coatings, Materials, andApplications and is the direct responsibility of
Subcommittee D01.42 on Architectural Coatings. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved April 1, 2019. Published April 2019. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2012. Last previous edition approved in 2013 as D7786 – 13. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D7786-13R19. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7786 − 13 (2019)
topcoats with respect to their ability to provide good enamel
holdout. Primer/topcoat systems with the best enamel holdout
will result in desirable gloss in the first coat of topcoat
application.
6. Apparatus
6.1 Film Applicator, preferably a drawdown bar, capable of
applying wet-film thickness of approximately 0.075 mm (3.0
mils).
6.2 If preferred, brush, roller, or spray applicators can be
substituted for the drawdown applicators.
FIG. 1 Diagram of Perpendicular Drawdown Technique
6.3 Gloss Meter capable of measuring 20 and 60° gloss.
7. Reagents and Materials
9.1.4 Allow the topcoat to dry in a controlled environment
for an appropriate period of time for the topcoat that has been
7.1 Substrate Desired for Testing—The preferred substrate
applied. Report the environmental condition (°C, % RH) and
should have a uniform, flat surface to enable paint films to be
dry time interval.
applied with the preferred drawdown bar applicator. Unless
otherwise agreed upon, a non-porous, smooth drawdown card
9.2 Application of standard topcoat to non-porous, smooth
is used. Other commonly used substrates include: gypsum surface:
panel, wood, or drawdown cards with non-porous and porous
9.2.1 Apply the standard topcoat to the non-porous, smooth
sections. The choice to use an alternative substrate often substrate using the same film applicator as in section 9.1.3
necessitates the choice of an alternate applicator such as brush,
across the full length of the drawdown card. This application
roller, or spray. should be made at a similar time as the topcoat in step 9.1.3.
9.2.2 Allow the topcoat from step 9.2.1 to dry in a con-
7.2 Standard Paints—The topcoat will be a mutually
trolled environment for an appropriate period of time for the
agreed-upon standard topcoat. Unless otherwise agreed, use a
topcoat that has been applied. This environment and dry time
commercially available latex topcoat which yields a gloss
should be the same as in step 9.1.4. Report the environmental
between 40 and 55 when applied in accordance with 9.2.
condition (°C, % RH) and dry time interval.
8. Hazards 9.3 Gloss measurement:
9.3.1 Measure the gloss of the topcoat on both the primer/
8.1 The user of this test method should refer to appropriate
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