1、Designation: D 2454 08Standard Practice forDetermining the Effect of Overbaking on Organic Coatings1This standard is issued under the fixed designation D 2454; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisi
2、on. 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 covers the determination of the time-temperature effect of overbaking on the physical and chemicalproperties of org
3、anic coatings.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of whoever uses this standard to
4、 consult andestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.Specific hazard statements are given in Section 7.2. Referenced Documents2.1 ASTM Standards:2D 522 Test Methods for Mandrel Bend Test of AttachedOrganic CoatingsD 523
5、 Test Method for Specular GlossD 609 Practice for Preparation of Cold-Rolled Steel Panelsfor Testing Paint, Varnish, Conversion Coatings, andRelated Coating ProductsD 823 Practices for Producing Films of Uniform Thicknessof Paint, Varnish, and Related Products on Test PanelsD 1005 Test Method for Me
6、asurement of Dry-Film Thick-ness of Organic Coatings Using MicrometersD 1308 Test Method for Effect of Household Chemicals onClear and Pigmented Organic FinishesD 1400 Test Method for Nondestructive Measurement ofDry Film Thickness of Nonconductive CoatingsApplied toa Nonferrous Metal Base3D 1640 Te
7、st Methods for Drying, Curing, or Film Forma-tion of Organic Coatings at Room TemperatureD 1729 Practice for Visual Appraisal of Colors and ColorDifferences of Diffusely-Illuminated Opaque MaterialsD 1730 Practices for Preparation of Aluminum andAluminum-Alloy Surfaces for PaintingD 1731 Practices f
8、or Preparation of Hot-Dip AluminumSurfaces for PaintingD 2092 Guide for Preparation of Zinc-Coated (Galvanized)Steel Surfaces for Painting3D 2197 Test Method for Adhesion of Organic Coatings byScrape AdhesionD 2201 Practice for Preparation of Zinc-Coated and Zinc-Alloy-Coated Steel Panels for Testin
9、g Paint and RelatedCoating ProductsD 2244 Practice for Calculation of Color Tolerances andColor Differences from Instrumentally Measured ColorCoordinatesD 2794 Test Method for Resistance of Organic Coatings tothe Effects of Rapid Deformation (Impact)D 3359 Test Methods for Measuring Adhesion by Tape
10、 TestD 3363 Test Method for Film Hardness by Pencil TestD 7091 Practice for Nondestructive Measurement of DryFilm Thickness of Nonmagnetic Coatings Applied toFerrous Metals and Nonmagnetic, Nonconductive Coat-ings Applied to Non-Ferrous MetalsE 805 Practice for Identification of Instrumental Methods
11、 ofColor or Color-Difference Measurement of Materials3. Terminology3.1 Definition:3.1.1 overbaking, nan exposure of the coating to a mod-erately higher temperature or to a longer period of baking, orboth, than recommended by the manufacturer of the coating fornormal curing.3.1.1.1 DiscussionThis con
12、dition is in contrast to “heatresistance” which is a parameter relating to the service life ofa coating.4. Summary of Practice4.1 Four panels are prepared and baked at the schedulenormally recommended for the coating. Two of the panels arethen removed and the remaining two are subjected to anadditio
13、nal overbake in which the time and temperature aremutually agreed upon between the purchaser and the seller.The sets of panels, after a suitable conditioning interval, are1This practice is under the jurisdiction of ASTM Committee D01 on Paint andRelated Coatings, Materials, and Applications and is t
14、he direct responsibility ofSubcommittee D01.27 on Accelerated Testing.Current edition approved June 1, 2008. Published July 2008. Originally approvedin 1966. Last previous edition approved in 2002 as D 2454 95 (2002).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact AST
15、M Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.then evaluated for
16、 the properties that are compatible with thesubstrate. Among these are gloss, color, flexibility, adhesion,impact resistance, and resistance to reagents. Note that glasssubstrates should not be tested for impact, and zinc-coatedsubstrates can influence both flexibility and impact.5. Significance and
17、 Use5.1 Most coatings are designed for a specific baking timeand temperature. For a variety of reasons (line stoppages,rerouting back through ovens, oven overheating, etc.) theprescribed time or temperature, or both, of the bake is oftenexceeded. This practice has been found to be useful inevaluatin
18、g the effects of overbakes on coatings.6. Materials6.1 Standard Baking-Type Coating mutually agreed uponbetween the purchaser and the seller.7. Hazards7.1 The flash points of most solvents used in many organiccoatings and related products are low enough that adequateventilation is needed to avoid ex
19、ceeding 25 % of the lowerexplosive limits of the solvents when test panels are beingprepared and baked. As these materials are considered toxic,take care to avoid inhalation of solvent vapor and unnecessarycontact of solvent with the skin.8. Procedure8.1 Application of Organic Coating:8.1.1 Apply co
20、atings to steel panels prepared in accordancewith Practice D 609.8.1.2 Apply coatings to zinc-coated surfaces prepared inaccordance with Guide D 2092, when zinc has been applied bythe hot-dip method or by electroplating.8.1.3 Apply coatings to nonpassivated galvanized steelprepared in accordance wit
21、h Practice D 2201, when the zinc isapplied by a continuous galvanizing method using analuminum-bearing zinc.8.1.4 Apply coatings to aluminum surfaces on all-aluminummaterials prepared in accordance with Practices D 1730.8.1.5 Apply coatings to hot-dip aluminum coated surfacesprepared in accordance w
22、ith Practices D 1731.8.1.6 In cases where a primer is used in practice under thetopcoat, apply the entire system to the panels. The filmthickness of each coat shall be mutually agreed upon betweenthe purchaser and seller, but, in the absence of such agreement,the total thickness shall be 2 6 0.2 mil
23、s (50 6 5 m).8.1.7 In instances where clear coatings are to be tested, theymay be applied to aluminum or white carrara glass, one side ofwhich has been polished to a smooth, high-gloss finish. Otherselected substrata previously agreed upon between the pur-chaser and the seller may also be used. In t
24、he absence of aspecific agreement between the purchaser and the seller inregard to film thickness, apply the coatings by automatic spray.(Refer to Practices D 823, Method A) at a dry film thickness of2 6 0.2 mils (50 6 5 m). Multiple coats may be used to obtainthis film thickness where necessary due
25、 to the nature of thecoating material (Note 1). Manual spray application or thedrawdown method with wire-wound draw bars may be usedwhen automatic equipment is not available.NOTE 1Dry film thickness should be measured in accordance withTest Methods D 1005, D 7091,orD 1400, whichever is applicable. T
26、headhesion, flexibility, and color can vary considerably with thickness.8.2 Baking:8.2.1 The baking schedule for each coating includingprimer, topcoat, and primer/topcoat systems shall be mutuallyagreed upon between the purchaser and the seller and shallinclude the following:8.2.1.1 Normal Baking Sc
27、hedule (Time and Temperature)recommended for the development of optimum film properties,and8.2.1.2 Overbaking CycleThis cycle shall be within prac-tical limits in order to simulate conditions that might beencountered in actual production where baking oven or con-veyor lines, or both might malfunctio
28、n temporarily due tomechanical or electrical failure.8.3 Prepare four panels of each coating or coating systemand bake them at the schedule normally recommended toobtain optimum properties. Conduct the baking of these panelsin a mechanical recirculating air oven set to 62C of thespecified baking tem
29、perature. At the end of the specified timeremove two panels from the oven and subject the remainingtwo to the overbake cycle by:8.3.1 Acontinuation of the normal bake but for a previouslyagreed upon time, for example, 50 or 100 % increase in time,or8.3.2 Resetting the oven temperature to the agreed
30、overbaketemperature and then continuing the bake for a specified periodof time after the overbake temperature has been reached, orremoving the panels until the overbake temperature is reachedand then baking them for the agreed upon time.NOTE 2The conditions described in 8.3.2 are not usually reprodu
31、ciblebetween laboratories or different ovens because of variations in theheating characteristics of ovens.8.3.3 After the sets of panels have been baked according tothe mutually agreed upon baking cycles, place them in asuitable rack and condition for 24 h at 23 6 2C and 50 6 5%relative humidity (se
32、e Test Methods D 1640) prior to testing.Other conditioning terms may be agreed upon between thepurchaser and the seller.9. Test Methods9.1 Determine the properties of both sets of panels inaccordance with any or all of the following ASTM methods:9.1.1 GlossTest Method D 523.9.1.2 ColorPractice D 172
33、9 (Visual), Practice E 805 (in-strumental), or Practice D 2244.9.1.3 FlexibilityTest Methods D 522 (conical mandreland cylindrical mandrel).9.1.3.1 Heat-aged flexibility values should be determined inaccordance with a baking cycle that is in agreement betweenthe purchaser and the seller.9.1.4 Adhesi
34、onTest Methods D 21974(mechanical) orD 3359 (tape), or both.4This test method has been found to be inapplicable for powder coatings.D24540829.1.5 Impact ResistanceTest Method D 2794.59.1.6 HardnessTest Method D 3363 (pencil test).9.1.7 Exposure to ReagentsIf this test is desired, thechoice of materi
35、als to which the coating is to be exposed shallbe governed by the ultimate use of the coating and shall beagreed upon between the purchaser and the seller. The generalprocedure to be followed in this test is given in Test MethodD 1308.9.1.8 Other tests agreed upon between the purchaser and theseller
36、.10. Report10.1 Report the following information:10.1.1 Substrate employed, including type and thickness,10.1.2 Type of coating,10.1.3 Film thickness, including primer, if any,10.1.4 Normal bake schedule, or schedules,10.1.5 Overbake cycle,10.1.6 Test methods employed, and10.1.7 Values determined, i
37、ncluding the measured changesbetween the normal and overbake cycles.ASTM 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
38、 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 withdrawn. Your comments are in
39、vited 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 your comments have not receive
40、d 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 t
41、his 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).5It is suggested that impact resistance be determined by use of the GardnerVariable Impact Tester obtainable from the Gardner Laboratory, Inc., Bethesda, MD.D2454083
