1、Designation: D661 93 (Reapproved 2011)Standard Test Method forEvaluating Degree of Cracking of Exterior Paints1This standard is issued under the fixed designation D661; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of la
2、st revision. A number in parentheses indicates the year of last reapproval. Asuperscript 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. Scope1.1 This test method covers the evaluation
3、of the degree ofcracking of exterior paints by comparison with photographicstandards.2. Referenced Documents2.1 ASTM Standards:2D660 Test Method for Evaluating Degree of Checking ofExterior Paints2.2 Other Standards:Pictorial Standards of Coating Defects Handbook33. Terminology3.1 Definitions of Ter
4、ms Specific to This Standard:3.1.1 cracking, nthat phenomenon manifested in paintfilms by a break extending through to the surface painted.3.1.1.1 DiscussionWhere this is difficult to determine, thebreak should be called a crack only if the underlying surface isvisible. The use of a magnification of
5、 10 diameters is recom-mended in cases where it is difficult to differentiate betweencracking and checking (see Test Method D660).4. Significance and Use4.1 Cracking failure of paint films can occur in use. This testmethod provides a means of evaluating the degree of the failureby comparing the pict
6、orial standards.5. Types of Cracking5.1 Three types of cracking are recognized:5.1.1 Irregular Pattern TypeCracking in which the breaksin the film are in no definite pattern.5.1.2 Line TypeCracking in which the breaks in the filmare generally arranged in parallel lines, usually either horizon-tally
7、or vertically, over the surface of the film. These breaksoften follow the line of brush marks.5.1.3 Sigmoid TypeCracking in which the breaks in thefilm form a pattern consisting of curves meeting and intersect-ing, usually on a relatively large scale.6. Use of Photographic Reference Standards6.1 The
8、 photographic reference standards that are part ofthis test method and are provided in the Pictorial Standards ofCoating Defects Handbook are representative of the degree ofcracking of exterior paint films. Fig. 1 is for illustrationpurposes only and should not be used for evaluation.6.2 The use of
9、the photographic reference standards3illus-trated in Fig. 1 requires the following precautions:6.2.1 The accompanying photographic reference standardsshow line-type cracking only. Irregular and sigmoid-typecracking may also be interpreted from these photographs.6.2.2 Care must be taken not to confus
10、e various types offailure that may be present on the same surface. This isparticularly true in observing cracking and checking. Crackingmay very often be an advanced stage of checking and is veryoften in evidence along with checking and other failures.6.2.3 It must be realized that the degree of fai
11、lure will varyover any given area. Therefore, an average portion of the filmshould be used for comparison. On larger surfaces it isrecommended that ratings be made at several locations and themean and range reported.6.2.4 Paint films may collect excessive quantities of dirt,which may mask the type a
12、nd degree of failure. If necessary,dirt should be removed by careful and gentle brushing with amoderately soft brush.6.2.5 In examining wood panels for cracking failure, thepossibility of wood failure should be recognized. This takes theform of a cracking or splitting of the wood itself with aresult
13、ant rupture of the paint film. Also, some panels will1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.25 on Evaluation of Weathering Effects.Current edition approved Nov. 1,
14、 2011. Published November 2011. Originallyapproved in 1942. Last previous edition approved in 2005 as D661 93 (2005).DOI: 10.1520/D0661-93R11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards vol
15、ume information, refer to the standards Document Summary page onthe ASTM website.3Copies of the pictorial photographic reference standards are contained in thepublication Pictorial Standards of Coatings Defects and may be obtained from theFederation of Societies for Coatings Technology, 492 Norristo
16、wn Rd., Blue Bell,PA 19422. The silver halide-gelatin photographs are intended to be the only primaryreference standards for this method. The reproductions of them in this test methodare for the purpose of illustration only.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Cons
17、hohocken, PA 19428-2959, United States.FIG. 1 Degrees of CrackingD661 93 (2011)2develop “resin spewing” which will cause early failure bycracking. These points should be taken into consideration inany evaluations.6.3 For convenience in recording the data obtained, therecords should be kept on forms
18、agreed upon between thepurchaser and the seller.7. Precision and Bias7.1 No precision or bias statement has been established forthis test method.8. Keywords8.1 cracking; evaluation; reference standardsASTM International takes no position respecting the validity of any patent rights asserted in conne
19、ction with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsi
20、ble technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful co
21、nsideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100
22、 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D661 93 (2011)3
