1、Designation: C538 83 (Reapproved 2014)1Standard Test Method forColor Retention of Red, Orange, and Yellow PorcelainEnamels1This standard is issued under the fixed designation C538; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, th
2、e 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.1NOTEIntroduction was added and minor units abbrevation corrections made editorially in June 2014.INTRODUCTIONThe purpos
3、e of this test is to detect those red, yellow, orange, and some green porcelain enamelsthat are likely to experience appreciable color changes upon exposure to atmospheric corrosion.1. Scope1.1 This test method2covers only porcelain enamels con-taining the cadmium-sulfide or cadmium sulfo-selenide t
4、ypesof pigments. The purpose of the test is to detect those red,yellow, orange, and some green porcelain enamels that arelikely to experience appreciable color changes upon exposureto atmospheric corrosion.1.2 This standard does not purport to address all of thesafety concerns, if any, associated wi
5、th 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.2. Summary of Test Method2.1 Cupric sulfate solution is placed on the surface ofappropriate samples and allow
6、ed to remain for 20 h undercontrolled illumination. The samples are then washed, dried,and examined visually for a darkening of the color in the testedarea.3. Significance and Use3.1 Correlation between results of this test and outdoorexposure tests of porcelain enamels colored with cadmiumsulfo-sel
7、enide pigment shows that the cupric sulfate test is aneffective indicator of the tendency for such coatings to expe-rience appreciable color changes during weathering. The cu-pric sulfate test is considered useful for specificationacceptance, quality control, and research and developmentpurposes.4.
8、Interferences4.1 In some cases, the treatment may change the gloss of thetested area. Any such gloss change shall be disregarded.5. Apparatus for Control of Illumination5.1 The light source shall consist of a 110 V, 15 W coolwhite fluorescent lamp (designation F15 T8CW), 25.4 mm (1in.) in diameter b
9、y 457.2 mm (18 in.) long. Center the lampnear the top of a box, made from plywood or other suitablematerial, in such a position that the distance between thespecimen surface and the centerline of the lamp is 228.6 mm (9in.). The box, with inside dimensions of 508 by 152 by 305 mm(20 by 6 by 12 in.)
10、(length by width by height), shall be paintedwith a matte (flat), neutral white paint on the inside, and shallbe vented for air circulation. Venting is accomplished by 11holes, 12.7 mm (12 in.) in diameter, drilled 25.4 mm (1 in.)apart on a centerline 25.4 mm (1 in.) from the inside top, and11 simil
11、ar holes drilled on a centerline 25.4 mm (1 in.) from thebottom on each of the two long sides.6. Reagents6.1 The cupric sulfate solution is prepared by placing 50 gof cupric sulfate (CuSO45H2O), reagent grade, in 100 mL ofhot distilled water in a glass container, and permitting themixture to age at
12、room temperature (27 6 5C) (80 6 10F)for 16 h or longer with occasional stirring. This treatmentproduces a solution with some undissolved material remainingat the bottom of the container.7. Specimens7.1 Any size specimen larger than 50.8 by 50.8 mm (2 by 2in.) may be used. Specimens should be reason
13、ably flat.1This test method is under the jurisdiction ofASTM Committee B08 on Metallicand Inorganic Coatingsand is the direct responsibility of Subcommittee B08.12 onMaterials for Porcelain Enamel and Ceramic-Metal Systems.Current edition approved May 1, 2014. Published June 2014. Originallyapproved
14、 in 1964. Last previous edition approved in 2009 as C538 83 (2009).DOI: 10.1520/C0538-83R141.2This test method is based on the Cupric Sulfate Test for Color Retention,Bulletin T-22 on the Porcelain Enamel Inst., Arlington, VA.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Con
15、shohocken, PA 19428-2959. United States18. Procedure8.1 Clean the specimen by washing with soap and water,followed by copious rinsing with clean, but not necessarilydistilled, water. Dry the surface with a clean dry towel byblotting or gentle rubbing.8.2 Place several drops of the solution on the ho
16、rizontal testarea to form a pool, and immediately cover with a clean 25 mm(1 in.) diameter watch glass (with fire-polished edges) in theinverted position. The quantity of solution used shall besufficient to fill the inverted watch glass except for a smallbubble of entrapped air. Remove any excess so
17、lution from thetest area not under the watch glass. In some cases, it may benecessary to seal the area of contact between the watch glassand the specimen surface (with some material such as model-ing clay or rubber cement) to prevent escape of the solution.8.3 Place the specimen with watch glass in
18、position underthe light-chamber. It should remain in this position for 20 h ina room at 27 6 5C (80 6 10F). If the solution has escaped ordried out at the end of the test period, the test is invalid andshall be repeated on a different location on the specimensurface.8.4 After exposure, remove the wa
19、tch glass, rinse the treatedarea with water to remove all of the test solution, and dry witha clean cloth.8.5 Visually examine the specimen immediately to deter-mine whether there has been any darkening of the treated area.Use partially diffused daylight supplemented, if necessary, byartificial ligh
20、t, the total intensity being approximately thatavailable within a few feet of an outside window, but do notexamine in direct sunlight. During observation, hold thespecimen no nearer the light source (such as a window) thanthe minimum width of the source.8.6 If any darkening can be detected visually,
21、 the specimenfails the test. Changes in gloss caused by the treatment shall notbe considered in the grading.9. Report9.1 Report the type, color, and number of specimens tested,and whether each passed or failed the test.10. Precision and Bias10.1 A precision and bias statement is not applicable to th
22、istest method, since it is a pass/fail test.11. Keywords11.1 color retention; porcelain enamel; red, orange, andyellow cadmium sulfo-selenide pigmentsASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. User
23、s 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 at any time by the responsible technical committee and must be reviewed every
24、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 comments will receive careful consideration at a meeting of theresponsible technica
25、l 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 by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken,
26、 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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).C538 83 (2014)12
