1、Designation: C 538 83 (Reapproved 2004)e1Standard Test Method forColor Retention of Red, Orange, and Yellow PorcelainEnamels1This standard is issued under the fixed designation C 538; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、 the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTEKeywords were added editorially in September 2004.1. Scope1.1 This test method2covers only porcelain enamels c
3、on-taining the cadmium-sulfide or cadmium sulfo-selenide typesof 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 t
4、o 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.2. Summary of Test Method2.1 Cupric sulfate solutio
5、n is placed on the surface ofappropriate samples and allowed 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 outdoorexposur
6、e tests of porcelain enamels colored with cadmiumsulfo-selenide 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 specification accep-tanc
7、e, quality control, and research and development purposes.4. 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 fluoresc
8、ent lamp (designation F 15 T8CW), 25.4 mm (1in.) in diameter by 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
9、 inside dimensions of 508 by 152 by 305 mm(20 by 6 by 12 in.) (length, width, height), shall be painted witha matte (flat), neutral white paint on the inside, and shall bevented for air circulation. Venting is accomplished by 11 holes,12.7 mm (12 in.) in diameter, drilled 25.4 mm (1 in.) apart ona c
10、enterline 25.4 mm (1 in.) from the inside top, and 11 similarholes drilled on a centerline 25.4 mm (1 in.) from the bottomon 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
11、in a glass container, and permitting themixture to age at 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 5
12、0.8 mm (2 by 2in.) may be used. Specimens should be reasonably flat.8. 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 dro
13、ps of the solution on the horizontal 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 entrapp
14、ed air. Remove any excess solution from the1This test method is under the jurisdiction of ASTM Committee B08 on Metallicand Inorganic Coatings and is the direct responsibility of Subcommittee B08.12 onMaterials for Porcelain Enamel and Ceramic-Metal Systems.Current edition approved Aug. 1, 2004. Pub
15、lished September 2004. Originallyapproved in 1964. Last previous edition approved in 1998 as C 538 83 (1998).2This test method is based on the Cupric Sulfate Test for Color Retention,Bulletin T-22 on the Porcelain Enamel Inst., Arlington, VA.1Copyright ASTM International, 100 Barr Harbor Drive, PO B
16、ox C700, West Conshohocken, PA 19428-2959, United States.test 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
17、.3 Place the specimen with watch glass in 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 specime
18、nsurface.8.4 After exposure, remove the watch 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 sup
19、plemented, if necessary, byartificial light, 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
20、If any darkening can be detected visually, 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
21、and bias statement is not applicable to thistest 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 wit
22、h any item mentionedin this standard. Users 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 techn
23、ical committee and must be reviewed every 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 considerati
24、on at a meeting of theresponsible technical 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 Har
25、bor 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).C 538 83 (2004)e12
