1、Designation:D730607(Reapproved 2013)Standard Practice forTesting Low Temperature Film-Formation of Latex Paints byVisual Observation1This standard is issued under the fixed designation D7306;the number immediately following the designation indicates the year oforiginal adoption or,in the case of rev
2、ision,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.1.Scope1.1 This practice specifies a laboratory procedure for evalu-ating the ability of a latex paint to form a uni
3、form film free ofvisible defects at low temperatures.1.2 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibil
4、ity 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:2D823 Practices for Producing Films of Uniform Thicknessof Paint,Varnish,and Related Products on Tes
5、t PanelsD3793 Test Method for Low-Temperature Coalescence ofLatex Paint Films by Porosity Measurement(Withdrawn2012)33.Terminology3.1 Definitions:3.1.1 low temperature coalescence(LTC),nthe ability ofa latex paint to form a film at low termperatures,typically4 6 2C(39 6 4F).4.Summary of Practice4.1
6、The paint,applicator and the test panel are allowed toequilibrate for at least 4 h at 4 6 2C(39 6 4F).The test paintis applied to a part-sealed/part-unsealed drawdown chart andimmediately placed in a cold cabinet.4.2 After 18 h the panel is removed from the cold cabinetand evaluated for any cracking
7、 of the paint film.NOTE1Temperature of film formation testing may be altered uponmutual consent of all parties involved.5.Significance and Use5.1 This practice can be used by paint formulators todetermine if a given paint has the ability to form a film at lowtemperatures.This practice can be used as
8、 an aid for determin-ing coalescing solvent level required to form a good film.TestMethod D3793 compares the porosity of a film drawn down atroom temperature to another film drawn down and cured at lowtemperature.5.2 This practice provides no absolute information,ratherranking only of the selected s
9、eries of paints.5.3 This practice can provide a pass-fail situation if knownacceptable and unacceptable paints are included in the test.6.Apparatus and Materials6.1 Vacuum Plate.6.2 Paint Test Chart with sealed and unsealed evaluationareas.46.3 Paint Applicator(s),typically to apply 3 and 10 mil wet
10、film thickness of paint with higher thickness being moresevere.6.4 Cold Cabinet,maintaining 4 6 2C(39 6 4F)or adifferent temperature as agreed upon.6.5 Instrument,to record relative humidity(typically 20 to100%).NOTE2Variation in humidity can have impact on film formation.6.6 4X 12X Magnifying Glass
11、,6.7 Test Paint.1This practice is under the jurisdiction of ASTM Committee D01 on Paint andRelated Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.42 on Architectural Coatings.Current edition approved June 1,2013.Published June 2013.Originallyapproved in 2007.
12、Last previous edition approved in 2007 as D7306 07.DOI:10.1520/D7306-07R13.2For 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
13、 website.3The last approved version of this historical standard is referenced onwww.astm.org.4Paint test charts selected for use should be from a sole supply across theexperiment to ensure accurate comparisons between test samples.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West C
14、onshohocken,PA 19428-2959.United States1 7.Procedure7.1 Place the applicator,paint,and test panel in a coldcabinet and equilibrate for 4 h at 4 6 2C(39 6 4F),or asagreed upon.7.2 Secure a paint test chart with sealed and un-sealed areason a vacuum drawdown plate.7.3 After mixing the paint sample,dra
15、w down the paintuniformly using a straight bar applicator as in Practices D823.7.4 Immediately place the panel into the cold cabinet.7.5 After 18 h,remove the panel for evaluation as outlinedin 8.2.NOTE3This practice can be conducted at several thicknesses in orderto obtain a better understanding of
16、 low temperature film performance.Thicker films tend to increase the likelihood of cracking.NOTE4Variations in airflow within the cold cabinet can affect results.8.Report8.1 Examine the dried film for continuity under a magnify-ing glass.Report the degree of cracking over the sealed surfaceand the unsealed surface.Disregard cracking on the peripheryof the dried film.8.2 Rating system for each surface should be as follows:5=No cracking4=Slight cracking(visible with magnifying glass only)3=Some cr
