Standard Test Method for Film Hardness by Pencil Test

SIGNIFICANCE AND USE
Pencil hardness measurements have been used by the coatings industry for many years to determine the hardness of clear and pigmented organic coating films. This test method has also been used to determine the cure of these coatings, especially when forced dried using heat.
This test method is especially useful in developmental work and in production control testing in a single laboratory. It should be recognized that the results obtained may vary between different laboratories when different pencils as well as panels are used. Every effort should be made to standardize the hardness of the lead used and the technique followed.
If this test method is used as a basis for purchase agreement, maximum precision will be achieved if a given set of referee pencils be agreed upon between the purchaser and the seller.
SCOPE
1.1 This test method covers a procedure for rapid, inexpensive determination of the film hardness of an organic coating on a substrate in terms of drawing leads or pencil leads of known hardness.
1.2 This test method is similar in content (but not technically equivalent) to ISO 15184.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.4 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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Publication Date
31-May-2011
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ASTM D3363-05(2011) - Standard Test Method for Film Hardness by Pencil Test
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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:D3363–05(Reapproved2011)
Standard Test Method for
Film Hardness by Pencil Test
This standard is issued under the fixed designation D3363; 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.
1. Scope* clear and pigmented organic coating films. This test method
has also been used to determine the cure of these coatings,
1.1 This test method covers a procedure for rapid, inexpen-
especially when forced dried using heat.
sive determination of the film hardness of an organic coating
4.2 This test method is especially useful in developmental
on a substrate in terms of drawing leads or pencil leads of
work and in production control testing in a single laboratory. It
known hardness.
should be recognized that the results obtained may vary
1.2 This test method is similar in content (but not techni-
between different laboratories when different pencils as well as
cally equivalent) to ISO 15184.
panels are used. Every effort should be made to standardize the
1.3 The values stated in SI units are to be regarded as the
hardness of the lead used and the technique followed.
standard. The values given in parentheses are for information
4.3 If this test method is used as a basis for purchase
only.
agreement, maximum precision will be achieved if a given set
1.4 This standard does not purport to address all of the
of referee pencils be agreed upon between the purchaser and
safety concerns, if any, associated with its use. It is the
the seller.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
5. Apparatus
bility of regulatory limitations prior to use.
5.1 A set of calibrated drawing leads (preferred) or equiva-
2. Referenced Documents lent calibrated wood pencils meeting the following scale of
hardness:
2.1 Other Standards:
ISO 15184 Determination of film hardness by pencil test. 6B25B24B23B22B2B2HB2F2H22H23H24H25H26H
Softer Harder
3. Summary of Test Method
(1)
3.1 A coated panel is placed on a firm horizontal surface.
The difference between two adjacent leads shall be consid-
The pencil is held firmly against the film at a 45° angle (point
ered one unit of hardness.
away from the operator) and pushed away from the operator in
5.2 Mechanical Lead Holder, for drawing leads if used.
a6.5-mm( ⁄4-in.)stroke.Theprocessisstartedwiththehardest
5.3 Mechanical Sharpener, draftsman-type, is helpful for
pencil and continued down the scale of hardness to either of
trimming wood pencils if used.
two end points: one, the pencil that will not cut into or gouge
5.4 Abrasive Paper, grit No. 400.
the film (pencil hardness), or two, the pencil that will not
6. Test Specimens and Conditions
scratch the film (scratch hardness).
6.1 Apply the surface coating by appropriate means to a
4. Significance and Use
smooth rigid substrate and cure properly, or use representative
4.1 Pencil hardness measurements have been used by the
panels cut from coated stock. The panels used, the curing
coatings industry for many years to determine the hardness of
conditions, and the age of the coating prior to the test shall be
within the limits agreed upon between the purchaser and the
seller.
This test method is under the jurisdiction of ASTM Committee D01 on Paint
6.2 The film thickness of the coating shall be as specified or
and Related Coatings, Materials, andApplications and is the direct responsibility of
Subcommittee D01.23 on Physical Properties of Applied Paint Films. as agreed upon between the purchaser and the seller.
Current edition approved June 1, 2011. Published June 2011. Originally
6.3 Conduct the test at 23 6 2°C (73.5 6 3.5°F) and 50 6
approved in 1974. Last previous edition approved in 2005 as D3363 – 05. DOI:
5 % relative humidity.
10.1520/D3363-05R11.
Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org.
*A Summary of Changes section appears at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D3363–05 (2011)
7. Procedure
7.1 For wood pencils, remove approximately 5 to 6 mm ( ⁄16
to ⁄4 in.) of wood from the point of each pencil using a
draftsman-type mechanical sharpener, being careful to leave an
undisturbed, unmarked, smooth cylinder of lead. Holding the
pencil holder (when using drawing leads) at an angle of 90° to
the abrasive paper, rub the lead against the paper maintaining
an exact angle of 90° to the abrasive paper until a flat, smooth
and circular cross section is obtained, free of chips or nicks in
the edge of the cross section. For wood pencils, see Fig. 1 for
an illustration. For mechanical pencil holders with drawing
leads, see Fig. 2 as the illustration. The desired edge may be
obtainedbycementingtheabrasivepapertoaflatmotor-driven
disk. By supporting the pencil at 90° to the rotating disk a
uniform flat lead end may be obtained more reproducibly.
7.2 For wood pencils, remove approximately 5 to 6 mm ( ⁄16
to ⁄4 in.) of wood from the point of each pencil using a FIG. 2 View of Me
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