1、Designation: D 4946 89 (Reapproved 2003)Standard Test Method forBlocking Resistance of Architectural Paints1This standard is issued under the fixed designation D 4946; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of las
2、t revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes an accelerated procedure forevaluating the face-to-face blocking resistance of trades salespa
3、ints. This is not to be confused with blocking resistance TestMethod D 3003, which is concerned with blocking of industrialcoatings on metal substrates, nor with Test Method D 2793which is concerned specifically with wood product finishes andreports results on a satisfactory or not satisfactory basi
4、s, ratherthan by the degree of blocking tendency as in this test method.1.2 The values stated in the SI units of measurement are tobe regarded as the standard. The values given in parenthesesare for information only.1.3 This standard does not purport to address all of thesafety concerns, if any, ass
5、ociated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:D 16 Terminology for Paint, Related Coatings, Materials,a
6、nd Applications2D 2793 Test Method for Block Resistance of Organic Coat-ings on Wood Panel Substrates3D 3003 Test Method for Pressure Mottling and BlockingResistance of Organic Coatings on Metal Substrates33. Terminology3.1 Definition:3.1.1 blockingThe undesirable sticking together of twopainted sur
7、faces when pressed together or placed in contactwith each other for an extended period of time, as referenced inTerminology D 16.4. Summary of Test Method4.1 Dried paint films are placed face-to-face and a pressureof about 127 g/cm2(1.8 psi ) is applied. These paint films areput into an oven for 30
8、min to make the test more stringent.After cooling, the blocked panels are peeled apart. The degreeof blocking is rated subjectively for tack or seal using a seriesof standard descriptive terms corresponding to numericalASTM values of 10 to 0.5. Significance and Use5.1 Dry paint often comes in contac
9、t with itself especially inwindow and door areas and, depending on its hardness, thepressure, temperature, humidity, and duration of time thesurfaces are in contact, sometimes sticks to itself (blocks). Thisstringent test method can be used to compare and ratesubjectively the resistance of paints to
10、 blocking.6. Apparatus6.1 Conditioned Room, at 18 to 29.5C (65 to 85F ) and 40to 60 % relative humidity.6.2 Sealed Paper Test Charts, approximately 190 by 280mm (7.5 by 11 in.).6.3 Applicator Blade, 13 to 15 cm (5 to 6 in.) wide,0.15mm (6mil) clearance.6.4 Oven, 48 to 52C (115 to 125F ).6.5 Rubber S
11、toppers, No. 8, 3.2 cm (1.25 in.) smallerdiameter.6.6 Weights, 1000 g.6.7 Scissors.6.8 Aluminum Tray or Pan, flat.7. Procedure7.1 Cast the paint to be tested on a sealed test chart using theapplicator blade. Condition coated panels in the conditionedroom for seven days. All painted panels should be
12、kept free ofgrease, oil, or fingerprints since these will affect block resis-tance.7.2 After the panels have been conditioned, cut out six 3.8by 3.8-cm (112 by 112-in. ) sections from the painted chart.Start the cut at least 1.3 cm (12 in.) away from the edge of thedrawdown.7.3 Place the cut section
13、s with the paint surfaces face-to-face for each paint to be tested.7.4 The weights, stoppers, and tray should be temperatureequilibrated in the oven prior to running the test.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications a
14、nd is the direct responsibility ofSubcommittee D01.42 on Architectural Coatings.Current edition approved Oct. 1, 2003. Published October 2003. Originallyapproved in 1989. Last previous edition approved in 1989 as D 4946 89 (1999).2Annual Book of ASTM Standards, Vol 06.01.3Annual Book of ASTM Standar
15、ds, Vol 06.02.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7.5 Place the face-to-face specimens in the oven on a flataluminum tray. Place a No. 8 stopper on top, with the smalldiameter in contact with the specimens, then place a 1
16、000-gweight on top of the stopper. This results in a pressure of 127g/cm2(1.8 psi) on the specimens. One weight and stopper is tobe used for each specimen to be tested. It is recommended that“pass” and “fail” paint controls be used in each test run and thatthe tests be run in triplicate.7.6 After ex
17、actly 30 min, take the stoppers and weights offthe test specimens and remove them from the oven. Allowthem to cool for12 h in the conditioned room before determin-ing the block resistance.7.7 After cooling, separate the specimens by peeling themapart with a slow and steady force at about 180 from ea
18、chother forming a “T” pattern during beginning of the separation.It is necessary to put the specimen next to the ear whileseparating to actually hear the degree of tack. Rate for blockingresistance on a scale of 0 to 10 (see 8.2).8. Interpretation of Results8.1 Blocking resistance is rated on a scal
19、e of 10 to 0, whichcorresponds to a subjective tack (sound of separation whenpeeled) or seal (the complete sticking together) rating deter-mined by the operator. This rating system is defined in 8.2 inthe appropriate descriptive terms. The degree of seal is theestimated area on the specimens where t
20、he paint surfacesadhere and some of the paper tears away from the chart whenpeeled.8.2 Blocking Resistance Ratings:BlockingResistanceNumerical RatingsType of Separation Performance10 no tack perfect9 trace tack excellent8 very slight tack very good7 very slight to slight tack good to very good6 slig
21、ht tack good5 moderate tack fair4 very tacky; no seal poor to fair3 5 to 25 % seal poor2 25 to 50 % seal poor1 50 to 75 % seal very poor0 75 to 100 % seal very poor9. Report9.1 Report the blocking resistance rating determined inaccordance with 8.2.10. Precision10.1 Data are unavailable for a convent
22、ional precisionstatement. However, based on actual laboratory experience,with experienced operators, the repeatability is estimated to beplus or minus one blocking resistance unit. Numerical valuesmay differ from operator to operator but relative rankingshould be about the same. As in many tests the
23、 precisionimproves with practice.11. Keywords11.1 blocking; blocking resistance; sticking; tackASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determina
24、tion 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 responsible technical committee and must be reviewed every five years andif not revised, either reapproved or with
25、drawn. 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 consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that you
26、r 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 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).D 4946 89 (2003)2
