ASTM_C_679_-_15.pdf

Designation:C67915Standard Test Method forTack-Free Time of Elastomeric Sealants1This standard is issued under the fixed designation C679;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 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 U.S.Department of Defense.1.Scope1.1 This test method covers a procedure for the determina-tion of the 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 extrusion from the cartridge or gun are also describedby this test method.NOTE1See Specification C920 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 not 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.NOTE2Currently,there is no ISO standard similar to this specifica-tion.2.Referenced Documents2.1 ASTM Standards:2C717 Terminology of Building Seals and SealantsC920 Specification for Elastomeric Joint Sealants3.Terminology3.1 DefinitionsSee Terminology C717 for definitions ofthe following terms used in this test method:caulking,compound,cure,elastomeric,glazing,non-sag sealant,sealant,self-leveling sealant,and standard conditions.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 appearsclean 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 attachment 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 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 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 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 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 StandardConditions.6.2 Weight,rectangular,with dimensions of 41 by 19 mm(158in.long by34in.wide)and mass of 30 g(1.06 oz).1This test method is under the jurisdiction ofASTM Committee C24 on BuildingSeals and Sealants and is the direct responsibility of Subcommittee C24.20 onGeneral Test Methods.Current edition approved July 1,2015.Published September 2015.Originallyapproved in 1971.Last previous edition approved in 2009 as C679 091.DOI:10.1520/C0679-15.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 NOTE3The thickness of the weight should be approximately 6 mm(14in.)but planed to a thickness that will provide the 30-g(1.06-oz)mass.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 or more),rectangular,approximately 152 by 76 mm(6 by 3 in.),made ofnon-porous material such as tin plated s