1、Designation: C 679 03Standard Test Method forTack-Free Time of Elastomeric Sealants1This standard is issued under the fixed designation C 679; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in p
2、arentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 a procedure for the determina-tion of th
3、e tack-free time property of single- and multi-component elastomeric sealants commonly used for sealing,caulking, and glazing in buildings and related construction.1.2 This test method is applicable to self-leveling andnon-sag grades of sealant. Sealants requiring slight heating tofacilitate extrusi
4、on from the cartridge or gun are also describedby this test method.NOTE 1See Specification C 920 for type and grade definitions.1.3 The values stated in metric units are to be regarded asthe standard. The values given in parentheses are provided forinformation purposes only.1.4 This standard does no
5、t purport to address all of thesafety concerns, if any, associated 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.NOTE 2Currently, there is no ISO standar
6、d similar to this specifica-tion.2. Referenced Documents2.1 ASTM Standards:C 717 Terminology of Building Seals and Sealants2C 920 Specification for Elastomeric Joint Sealants23. Terminology3.1 DefinitionsSee Terminology C 717 for definitions ofthe following terms used in this test method: caulking,
7、com-pound, cure, elastomeric, glazing, non-sag sealant, sealant, andself-leveling sealant.4. Summary of Test Method4.1 The test consists of lightly touching a surface of a curingsealant with a polyethylene film at regular intervals until thesealant does not attach itself to the film and the film app
8、earsclean when peeled from the surface.4.2 More specifically a strip of polyethylene film is placedon the surface of the curing sealant and a 30-g (1.06-oz) weightis placed on the film. The weight is left in place for 30 s, thenremoved and the polyethylene strip is removed and examinedfor sealant at
9、tachment to the film. The length of time fromwhen the sealant was first applied and tooled into the templateuntil the time the sealant is no longer picked up by the film iscalled tack-free time.4.3 With some sealants, interpretation of the end point isconfusing in that a very thin film of sealant or
10、 oil will transferto the film. For consistency of data, record the point where thebulk sealant is no longer transferred to the plastic but ignore thevery thin uniform film of sealant or the plasticizer transferredto the plastic test strip.5. Significance and Use5.1 The tack-free time is a measure of
11、 the surface cure timeand may generally be correlated to a variety of useful param-eters such as the time interval before the sealant (1) resistsdamage by touch or light surface contact, (2) resists job-site orairborne dirt pick-up, (3) resists impinging rainfall.5.2 The tack-free time is sometimes
12、used as an on-the-jobquality assurance test. A quality product that is consistent andreproducible will generally fall within a maximum and mini-mum tack-free time.5.3 This test for tack-free time can be used at any tempera-ture and humidity. It is important that if a sealant will be usedin a climate
13、 quite different than the standard conditions calledout in this test method, then those conditions be used to test thesealant.6. Apparatus6.1 Cabinet or Room, capable of maintaining a temperatureof 23 6 2C (73.4 6 3.6F) and 50 % 6 5 % relative humidity.6.2 Weight, rectangular, with dimensions of 41
14、by 19 mm(158 in. long by34 in. wide) and mass of 30 g (1.06 oz).NOTE 3The thickness of the weight should be approximately 6 mm(14 in.) but planed to a thickness that will provide the 30-g (1.06-oz) mass.1This test method is under the jurisdiction of ASTM Committee C24 on BuildingSeals and Sealants a
15、nd is the direct responsibility of Subcommittee C24.20 onGeneral Test Methods.Current edition approved May 10, 2003. Published June 2003. Originallyapproved in 1971. Last previous edition approved in 1997 as C 679 87 (1997).2Annual Book of ASTM Standards, Vol 04.07.1Copyright ASTM International, 100
16、 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.3 Polyethylene Strips, several (often 6 or more), clear, lowdensity with dimensions 127 by 25 by 0.15 mm (5 by 1 by0.006 in.).6.4 Timer, capable of measuring minutes and hours.6.5 Rectangular Plates, several (often 6
17、or more), rectangu-lar, approximately 152 by 76 mm (6 by 3 in.), made ofnon-porous material such as tin plated steel or aluminum.6.6 Template, rectangular, of steel, brass or other suitablematerial, 3.2 mm (18 in.) thick with inside dimensions 95 by25.4 mm (334 by 1 in.); outside dimensions approxim
18、ately 120by 31 mm (534 by 2 in.).7. Sampling7.1 The test sample shall consist of a factory-sealed can ofcompound (minimum contents, 450 mL or 1 pt) with anappropriate curing agent where applicable, or a standardcartridge, factory filled and sealed.8. Procedure (see Fig. 1)8.1 Thoroughly clean the te
19、mplates and rectangular plateswith methyl ethyl ketone, xylene, or similar solvent.(WarningMethyl ethyl ketone, xylene, and similar solventsare both toxic and flammable and should be handled withcaution in a well ventilated hood.)8.2 Condition the sample of sealant in the original closedcontainer fo
20、r 24 h at 23 6 2C (73.4 6 3.6F) and 50 6 5%relative humidity. For single-component sealants, weigh outapproximately 250 g of the sealant before testing. For multi-component sealants, thoroughly mix 250 g of the base com-pound with the appropriate amount of curing agent followingthe manufacturers mix
21、ing instructions.8.3 Prepare at least two specimens for each sealant asfollows: Center the template on the metal plate and carefullyfill it with sealant avoiding air pockets. Strike off the surfaceflat using a metal straightedge, to a uniform thickness.8.4 Relative Tack-Free Time Unknown. If the rel
22、ative tack-free time is unknown, the procedure is to pretest one of the testspecimens by lightly touching the surface of the sealant with afilm of polyethylene wrapped over the end of a finger. Touchthe test piece in accordance with an appropriate time intervaldescribed in 8.5. Try to touch a differ
23、ent place on the surfaceeach time. After the polyethylene wrapped finger is lightlytouched to the surface of the sealant, it is immediately removedand examined to see if sealant was picked up on the polyeth-ylene film. When no sealant is picked up on the polyethylenestrip, perform the next test as d
24、escribed in 8.6.8.5 Time IntervalsIf the relative tack-free time is un-known, the procedure is to pretest, as in 8.4, one test specimeneach minute for the first 10 min, each 2 min for the next 10min, each 5 min for the next 160 min (3 h has elapsed), eachhour for the next 69 h, each day until a posi
25、tive result isachieved or until 21 days has elapsed. Table 1 summarizes thetime intervals.NOTE 4Information provided by the manufacturer can save a greatdeal of time and lead the tester quickly to an appropriate time bracket.8.6 After the pretest in 8.4 do the actual test by starting new,but just be
26、fore the tack-free time estimated by the pretest. Atthe appropriate time lay a polyethylene strip over half of thesame test specimen and gently place the brass weight on thestrip and allow it to remain there for 30 s.8.7 Remove the weight and then slowly withdraw thepolyethylene strip pulling it wit
27、h thumb and forefinger at 90 tothe compound, at a constant rate of 1 in./15 s (see Fig. 1).8.8 If the strip is clean or almost clean, repeat the test of 8.6and 8.7 on a previously undisturbed test specimen.8.9 If the strip is clean from the previously undisturbed testspecimen, record the time from t
28、he moment the template wasscraped level with a spatula until the pulling of this strip.8.10 If the polyethylene strip still has sealant adhering to it,wait half the time of the preceding test time interval and repeatthe test described in 8.6 and 8.7 on another undisturbed testpiece.8.11 If the strip
29、 is again not clean, repeat 8.10 until a cleanstrip is achieved.8.12 If an approximate tack-free time is known, consultTable 1 and choose the total elapsed time interval that matchesthe supposed tack-free time, back down one interval and startthe pretest there and proceed with the pretest and test a
30、sdescribed above.FIG. 1 Stages in the Tack-Free Time Test ProcedureC6790328.13 If the tack-free time is shorter than anticipated, startwith fresh specimens and pick a shorter elapsed time as thestarting point.8.14 If the tack-free time occurred at an occasion when noone was available to check it (th
31、at is, night or weekend) startthe test over, at such a time where the anticipated final pointwill occur during working hours.NOTE 5Certain test conditions seem to have a particularly largeinfluence on the accuracy of this test and therefore should be closelywatched. Of prime importance is performing
32、 the test at the called outtemperature and humidity.9. Report9.1 Report the following information:9.1.1 Trade name or other identification of the sealanttested.9.1.2 Time of cure until no sealant was picked up on thepolyethylene sheet from 8.9. The time should be reported to thenearest minute, neare
33、st 2 min, or nearest 5 min, etc., asindicated by the time between tests. Record whether the filmwas clean or the film contained a thin layer of plasticizers.9.1.3 For Type M sealants describe the mixing systems, thetime taken to mix, and the time from after mixing and the startof the tack-free time
34、test.9.1.4 The temperature and relative humidity conditionsutilized to generate the results, if different from standardconditions.10. Precision and Bias310.1 Round-robin testing done at (23 6 2C) 73.4 6 3.6Fand 50 6 5 % relative humidity on five types of sealants byfive laboratories indicates the pr
35、ecision between laboratories is60 % of the test result (two standard deviations). No data isavailable to estimate precision within a laboratory. A summaryof results is given in Table 2.11. Keywords11.1 sealants; tack; tack-freeASTM International takes no position respecting the validity of any paten
36、t rights asserted in connection 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 a
37、t any time by the responsible 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 commen
38、ts will receive careful consideration 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
39、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-mai
40、l); or through the ASTM website(www.astm.org).3Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: C241024.TABLE 1 Summary of Time IntervalsFor First 10 MinTest Each MinuteFor Next 10 MinTest Each 2 MinFor Next 160 MinTest Each 5 Mi
41、nFor Next 69 hTest Each HourFor Next 18 DaysTest Each DayTotal time elapsed 10 min 20 min 3 h 3 days 21 daysTABLE 2 Precision SummaryTack-Free Time for ChemicalCuring Sealants (in hours)Material Average ValueBetweenLaboratoriesPercent BetweenD 0.278 0.047 17.138C 0.306 0.076 25.059B 12.200 6.340 51.970A 16.300 2.636 16.173E 53.600 27.005 50.383Average 1 standard deviation 32.144C679033
