1、Designation: C 1520 02Standard Guide forPaintability of Latex Sealants1This standard is issued under the fixed designation C 1520; 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 i
2、ndicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide describes the practical considerations thatmay be used to determine the compatibility of a paint orcoating to be applied over a latex sealant or c
3、aulk. It evaluatesthe appearance and not the performance characteristics of thecoated or painted joint.1.2 The committee with jurisdiction over this standard is notaware of any comparable standards published by other orga-nizations.1.3 This standard does not purport to address all of thesafety conce
4、rns, 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 requirements prior to use.2. Referenced Documents2.1 ASTM Standards:C 717 Terminology of Building Seals and
5、Sealants2D 1729 Practice for Visual Evaluation of Color Differencesof Opaque Materials3D 2244 Test Method for Calculation of Color Differencesfrom Instrumentally Measured Color Coordinates3E 284 Terminology of Appearance33. Terminology3.1 DefinitionsRefer to Terminology C 717 for definitionsof the f
6、ollowing term(s) used in this guide: compatibility, cure,joint, latex sealant. Refer to Terminology E 284 for definitionsof the following term(s) used in this guide: gloss.3.2 color changea change in either the observed (seePractice D 1729) or measured color (see Test Method D 2244)of a substance.3.
7、3 crackinga failure resulting in a discontinuous film (ofpaint) or bead (of sealant).4. Summary of Practice4.1 This guide reviews many of the issues concerning thecompatibility of latex sealants with paint. While the focus ofthis guide is on latex sealants, the paint or coating may be ofany composit
8、ion.5. Significance and Use5.1 The intent of this guide is to provide the reader withinformation concerning possible reasons for paint failureswhere the paint is used over a latex sealant.CONSIDERATIONS6. Temperature6.1 Since standard testing is usually performed at “roomtemperature,” about 22C, thi
9、s would be considered the idealtemperature for application and curing. As the temperaturedeviates from this ideal, the “science” of drying changes in asmuch as lower temperature results in slower drying and fasterdrying occurs at elevated temperatures.7. Percent Relative Humidity7.1 In waterborne se
10、alants, the humidity directly affects theability of the system to lose water. Standard testing is typicallydone at 50 % RH, which allows for an acceptable evaporationrate. Temperature and humidity variations in climatic regionsand fluctuations through the application and cure will havesignificant im
11、pacts.8. Type of Paint8.1 The type of paint applied to the sealant has an effect onhow well it may handle dimensional changes, adhere to thesealant or dry during the curing of the sealant. Paints madefrom more flexible resins (low Tg) with low pigment volumecontent (PVC) (PVC CPVC) will withstand th
12、e mostchange while a hard resin (high Tg) at high PVC will be the1This guide is under the jurisdiction of ASTM Committee C24 on Building Sealsand Sealants and is the direct responsibility of Subcommittee C24.10 on Specifi-cations, Guides and Practices.Current edition approved Jan. 10, 2002. Publishe
13、d April 2002.2Annual Book of ASTM Standards, Vol 04.07.3Annual Book of ASTM Standards, Vol 06.01.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.least forgiving. Broadly speaking, high gloss, interior paintsrepresent the former while
14、 interior flat paints represent thelatter.9. Type of Sealant9.1 The sealant will have an effect on adhesion of the paintfilm, the degree of change in geometry of the paint film andchanges in color and gloss. However, generally speaking, thesechanges are difficult to quantify by the type and quality
15、ofsealant.10. Cure Time10.1 The degree of sealant cure may affect the time to paint,the compatibility of the applied paint with the sealant, and thedry time of the applied paint. An uncured sealant may reactwith the paint ingredients. Cracking of the paint film may occurwhen the sealant is painted b
16、efore curing of the sealant bead iscomplete due to subsequent shrinkage of the underlyingsealant. Additionally, migration of sealant components to thebead surface may affect adhesion.11. Sealant Geometry/Tooling11.1 Use of a backing material usually helps to decreasesealant cracking and thereby also
17、 usually decrease paintfailure.12. Method of Paint Application12.1 The manner in which the paint is applied, that is, roller,brush or sprayer, may affect the thickness of the paint that isinitially applied. Some rollers and brushes, especially low costapplicators, may lose bristles or leave brush st
18、rokes or surfaceirregularities in the paint film, which may promote prematurefailures.13. Substrate Effects13.1 The porosity, composition and cleanliness of the sub-strate affect the cure of both sealant and paint. A more poroussubstrate will wick away water or solvent and shorten the paintcuring pe
19、riod. A difficult to adhere to substrate, or one thatconsists of material containing low molecular weight oils,plasticizers, etc., will affect film formation and wetting, andmay induce gloss and color change.14. Type of Construction14.1 This affects the substrates and amount of movementthat a paint/
20、sealant system may be subjected to.15. Lot to Lot Variation15.1 A number of factors contribute to lot to lot variation inboth sealants and paints. Whenever changing either, it may beprudent to test compatibility.OBSERVATIONS16. Cracking16.1 This may be simple cracking of the paint film or maymanifes
21、t itself as a crack in the sealant. The degree and amountof cracking between the sealant and the paint will affect theacceptability of this condition. Severe cracking of the sealantmay overwhelm the crack bridging ability of the paint film.17. Color Change17.1 This may be caused by the leaching of m
22、aterial fromeither the sealant or substrate into the paint and changing itsappearance. This may also be caused by the paint being moresusceptible to dirt pick-up, especially in areas where airbornedirt is prevalent.18. Gloss18.1 Plasticizer migration may cause the paint to develop ahigher more gloss
23、 over time.19. Keywords19.1 cracking; latex sealant; paintASTM 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 determination of the validity of any such pate
24、nt 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 withdrawn. Your comments are invited eith
25、er 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 your comments have not received a fair h
26、earing 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).C1520022
