ASTM D7488-10

Standard Test Method for Open Time of Latex Paints

SIGNIFICANCE AND USE
Latex paints dry very quickly which often causes difficulty in final appearance of painted areas, especially paints formulated below 100g/L VOC where lower amounts of solvents are in the formulated latex paint. This method is a means of determining the time available before a test paint cannot be worked into a previously painted area.
SCOPE
1.1 This test method covers a procedure to determine the length of time a latex paint remains “wet” or “open” enough to allow for brush-in and repair.
1.2 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.

General Information

• Status: Historical
• Publication Date: 30-Nov-2010
• ICS: 87.040 - Paints and varnishes
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.42 - Architectural Coatings

Relations

• Replaced By: ASTM D7488-11 - Standard Test Method for Open Time of Latex Paints
• Effective Date: 01-Jul-2011
• Referred By: ASTM D3730-17(2022) - Standard Guide for Testing High-Performance Interior Architectural Wall Coatings
• Effective Date: 01-Dec-2010

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D7488–10
Standard Test Method for
Open Time of Latex Paints
This standard is issued under the fixed designation D 7488; 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 a sealed chart with a 76 microns (3 mil) wet film thickness. X
marks are made immediately. The number of X marks will
1.1 This test method covers a procedure to determine the
dependonhowmanycanfitononedrawdown(seeFig.1).The
length of time a latex paint remains “wet” or “open” enough to
test paint is then applied in perpendicular sections, brushing
allow for brush-in and repair.
each section across the initial painted section. The perpendicu-
1.2 This standard does not purport to address all of the
lar sections are repeated at agreed upon time intervals. After
safety concerns, if any, associated with its use. It is the
drying,wetedgeisrecordedasthelasttimethetestpaintcould
responsibility of the user of this standard to establish appro-
be brushed into the initial painted section without the edges of
priate safety and health practices and determine the applica-
the first coat being visible. The time at which the X marks
bility of regulatory limitations prior to use.
become visible is also noted.
2. Referenced Documents
5. Significance and Use
2.1 ASTM Standards:
5.1 Latex paints dry very quickly which often causes
D3924 Specification for Environment for Conditioning and
difficulty in final appearance of painted areas, especially paints
Testing Paint, Varnish, Lacquer, and Related Materials
formulated below 100g/L VOC where lower amounts of
D5068 Practice for Preparation of Paint Brushes for Evalu-
solvents are in the formulated latex paint. This method is a
ation
means of determining the time available before a test paint
D5301 Practice for Physical Characterization of Paint
cannot be worked into a previously painted area.
Brushes
E177 Practice for Use of the Terms Precision and Bias in
6. Apparatus
ASTM Test Methods
6.1 Constant Temperature/Humidity Room (23 6 2°C (73.5
E691 Practice for Conducting an Interlaboratory Study to
6 3.5°F)) / 50 6 5 % relative humidity in accordance with
Determine the Precision of a Test Method
Specification D3924.
3. Terminology 6.2 Contrasting Sealed Chart (that is, black sealed chart for
white paints or white sealed chart for tinted paints), typically
3.1 Definitions:
30 by 60 cm (1 by 2 ft.).
3.1.1 open time, n—thelengthoftimeacoatingremainswet
6.3 Glass Plate, 30 by 60 cm (1 by 2 ft.) or vacuum plate.
or open enough to allow for brush-in without the edges of the
6.3.1 If using a glass plate, tape to secure sealed chart to
first coat becoming visible and allowing for repair within the
glass plate.
previously painted area.
6.4 Good Quality Brush, 50 mm (2 in.) wide with straight
4. Summary of Test Method
edge, polyester bristles in accordance with Practice D5301.
6.5 Timer or Clock to record time intervals.
4.1 Since environmental conditions such as temperature,
6.6 Film Applicator, capable of applying a film with a width
humidity and air flow can result in variable results, it is
of 7.5 cm (3 in.) and approximate wet film thickness of 75
recommended that this test method be performed in a constant
microns (3 mil).
temperature / humidity room (23 6 2°C (73.5 6 3.5°F)) / 50
65 %relativehumidity.Testpaintsareappliedtothecenterof
7. Procedure
7.1 Condition the brush in accordance with Practice D5068.
This test method is under the jurisdiction of ASTM Committee D01 on Paint
7.2 Tapetheedgesofthecharttoasmoothglassplateoruse
and Related Coatings, Materials, andApplications and is the direct responsibility of
a vacuum plate.
Subcommittee D01.42 on Architectural Coatings.
7.3 Along the length of the panel, drawdown 76 microns (3
Current edition approved Dec. 1, 2010. Published February 2011. DOI: 10.1520/
D7488–10.
mil) wet film thickness of the test paint (see Fig. 1). The
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
drawdown must be free of ridges, craters, or other imperfec-
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
tions.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
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D7488–10
TABLE 1 Time Elapsed When Edges of First Coat Become
Visible (minutes)
A
Average Repeatability Reproducibility
Limit Limit
Material Xbar r R R / Xbar
Paint A 2.33 1.50 2.71 1.16
Paint B 2.18 0.83 1.64 0.75
Paint C 2.04 0.83 0.83 0.41
Paint D 3.02 1.77 3.87 1.28
A
The average of the laboratories’ calculated averages.
TABLE 2 Time Elapsed When the X Marks Become Visible
(minutes)
A
Average Repeatability Reproducibility
Limit Limit
Material Xbar r R R / Xbar
Paint A 4.51 2.64 5.95 1.32
Paint B 3.02 2.04 3.40 1.12
Paint C 3.11 1.45 3.96 1.27
Paint D 6.33 3.04 8.44 1.33
A
The average of the laboratories’ calculated averages.
7.9 Dry the chart in a horizontal position overnight.
7.10 After drying overnight, o
...