Standard Test Method for Evaluating Adhesion by Knife

SCOPE
1.1 This test method covers the procedure for assessing the adhesion of coating films to substrate by using a knife.
1.2 This test method is used to establish whether the adhesion of a coating to a substrate or to another coating (in multi-coat systems) is at a generally adequate level.Note 1
The term "substrate" relates to the basic surface on which a coating adheres (may be steel, concrete, etc. or other coating).
1.3 This method can be used in the laboratory and field.
1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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
30-Jun-2007
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ASTM D6677-07 - Standard Test Method for Evaluating Adhesion by Knife
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D6677 − 07
StandardTest Method for
1
Evaluating Adhesion by Knife
This standard is issued under the fixed designation D6677; 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 4. Significance and Use
1.1 This test method covers the procedure for assessing the 4.1 Coatings, to perform satisfactorily, must adhere to the
adhesion of coating films to substrate by using a knife. substrates on which they are applied.This test method has been
found useful as a simple means of assessing the adhesion of
1.2 This test method is used to establish whether the
coatings.Although this method is a qualitative and a subjective
adhesion of a coating to a substrate or to another coating (in
test it has been used in industry for many years and can provide
multi-coat systems) is at a generally adequate level.
valuable information.
NOTE 1—The term “substrate” relates to the basic surface on which a
4.2 Other adhesion test methods may be useful in obtaining
coating adheres (may be steel, concrete, etc. or other coating).
quantitative results. See D2197, D3359, D4541, and D7234.
1.3 This method can be used in the laboratory and field.
4.3 The Performance Evaluation Scale (see 7.4, Table 1)is
1.4 The values stated in SI units are to be regarded as the
based on both the degree of difficulty to remove the coating
standard. The values given in parentheses are for information
from the substrate and the size of removed coating.
only.
4.4 This test method does not have a known correlation to
1.5 This standard does not purport to address all of the
other adhesion test methods (pull-off, tape, etc.).
safety concerns, if any, associated with its use. It is the
4.5 A coating that has a high degree of cohesive strength
responsibility of the user of this standard to establish appro-
may appear to have worse adhesion than one that is brittle and
priate safety and health practices and determine the applica-
hence fractures easily when probed.
bility of regulatory limitations prior to use.
4.6 This method is not to be used on overly thick coatings,
2. Referenced Documents
that is, those which cannot be cut to the substrate with a utility
2
2.1 ASTM Standards:
knife in one stroke.
D2197 Test Method for Adhesion of Organic Coatings by
Scrape Adhesion 5. Apparatus and Materials
D3359 Test Methods for Measuring Adhesion by Tape Test
5.1 Cutting Tool—Sharp utility knife.
D4541 Test Method for Pull-Off Strength of Coatings Using
5.2 Cutting Guide—Steel or other hard metal straight edge
Portable Adhesion Testers
to ensure straight cuts.
D7234 Test Method for Pull-OffAdhesion Strength of Coat-
ings on Concrete Using Portable Pull-Off Adhesion Tes-
6. Test Specimen
ters
6.1 When this test method is used in the field, the specimen
3. Summary of Test Method isthecoatedsubstrateonwhichtheadhesionistobeevaluated.
3.1 Adhesion is determined by making an “X” cut into the 6.2 For laboratory use, apply the materials to be tested to
coating film to the substrate and by lifting the coating with a panels of the composition and surface conditions on which it is
knife. Adhesion is evaluated qualitatively ona0to10 scale. desired to determine adhesion.
NOTE 2—If desired or specified, the coated test panels may be subjected
1
to a preliminary exposure such as water immersion, salt spray, or high
This test method is under the jurisdiction of ASTM Committee D01 on Paint
and Related Coatings, Materials, andApplications and is the direct responsibility of humidity before conducting the knife adhesion test.
Subcommittee D01.46 on Industrial Protective Coatings.
Current edition approved July 1, 2007. Published August 2007. Originally 7. Procedure
approved in 2001. Last previous edition approved in 2001 as D6677 - 01. DOI:
7.1 Select an area free of blemishes and surface imperfec-
10.1520/D6677-07.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or tions.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
7.2 Using a sharp knife and cutting guide, make two cuts
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. into the coating with a 30 to 45 ° angle between legs and down
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D6677 − 07
TABLE 1 Rating System
7.5 After making several cuts examine the cutting edge and,
Rating Description if necessary, replace the blade.
10 Coating is extremely difficult to remove; fragments no larger than
1 1
appr
...

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