1、Designation: C756 87 (Reapproved 2016)Standard Test Method forCleanability of Surface Finishes1This standard is issued under the fixed designation C756; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A n
2、umber in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONThis test provides a procedure to quantify the cleanability of acid-resistant porcelain enamel usinga fluorescent water-soluble soil in
3、agent, a reproducible machine-wiping technique, and a means ofmeasuring the amount of residual soil by fluorescence.1. Scope1.1 This test method covers the numerical evaluation of theease or difficulty of cleaning soiled surface finishes. This testmethod is applicable to all surface finishes not aff
4、ected bywater.1.2 Values given in SI units are to be regarded as thestandard. Inch-pound units are provided for information only.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish
5、 appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C282 Test Method for Acid Resistance of Porcelain Enam-els(Citric Acid Spot Test)C614 Test Method for Alkali Resistance of Porcelain Enam-els3.
6、 Summary of Test Method3.1 The test method consists of applying an exact amount ofa fluorescent water-soluble soiling agent to a specimen surfaceand then cleaning the surface with a reproducible machine-wiping technique. The soil remaining on the specimen afterwiping is extracted with a water solven
7、t and the fluorescence ofthe solution measured. A standard reference surface is treatedin a similar manner. The cleanability index of the surface undertest is expressed as the ratio of the fluorescence of the solutionsextracted from the test surface and from the standard referencesurface. Cleanabili
8、ty indexes greater than 1.0 indicate that thetest surface is more difficult to clean than the standardreference surface, while indexes less than 1.0 indicate that thetest surface is more easily cleanable than the standard ofcomparison.3.2 The soiling agent used consists of polyethylene glycol,a blac
9、k dye, and a fluorescent tracer, each of which is readilywater soluble.4. Significance and Use4.1 This test method was developed to guide the user inselecting a finish coating or material that is resistant to soilingin a particular application.4.2 The numerical values derived by this test methodenab
10、les the user to rank finish coatings and materials in regardto soil retention or ease of soil removal.5. Apparatus5.1 Motor-Driven Lapping Plate, 203-mm (8-in.) diameter,speed 163 r/min.35.2 Automatic Polishing Unit, 11-s cycle, adjustable to48-mm (178-in.) stroke.45.3 Hypodermic Syringe, glass, 2-m
11、L capacity, withoutneedle.5.4 Repeating Pipet, 0.025 mL (25 l) capacity.5.5 Repeating Pipet, 10-mL capacity.1This test method is under the jurisdiction ofASTM Committee B08 on Metallicand Inorganic Coatings and is the direct responsibility of Subcommittee B08.12 onMaterials for Porcelain Enamel and
12、Ceramic-Metal Systems.Current edition approved Nov. 1, 2016. Published November 2016. Originallyapproved in 1973. Last previous edition approved in 2011 as C756 87 (2011)1.DOI: 10.1520/C0756-87R16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service a
13、t serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Suitable lapping plates are available from Buehler Ltd., 2120 Greenwood St.,Evanston, IL 60204, Struers, Inc., 20102 Progress Drive, Cleveland, OH, 44136; orother
14、Metallurgical Supply Sources.4An Olsen “S.M.” Automatic Polisher has been found suitable and is availableunder the code name OLPOL from Struers, Inc., 20102 Progress Drive, Cleveland,OH 44136.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United S
15、tates15.6 Desiccator approximately 254 mm (10 in.) diameter.5.7 Cleaning Head, brass, 57 mm (214 in.), with worm-driven hose clamp for attachment of cleaning tissues (Fig. 1).5.8 Soiling Head, brass, 25 mm (1 in.) diameter, with25-mm (1-in.) diameter facing of polytetrafluoroethylene at-tached with
16、a water-proof household cement (Fig. 1).5.9 Extraction Cell, fitted with a fluorosilicone O-ring, size3.2 by 57 mm (18 by 214 in.) (Fig. 2).55.10 Fluorometer, for measuring the fluorescence of solu-tions.65.11 0.9 Neutral Density Filter, 50.8 by 50.8 mm (2 by 2 in.)glass mounted (transmission 12.5 %
17、).5.12 Beakers, borosilicate, 100-mL capacity.6. Reagents and Materials6.1 Cleaning Tissues, approximately 127 by 229 mm (5 by9 in.).76.2 Potassium Carbonate.6.3 Polyethylene Glycol, 400.6.4 Uranine, water-soluble, USP.86.5 Keco Acid Black, B(F101).96.6 Ethyl Alcohol.6.7 Mild Household Detergent, li
18、quid.7. Test Specimens7.1 The preferred specimen size is 114 mm (412 in.) square,but any other size or shape may be used provided it can berotated on the lapping wheel and the smaller dimension isbetween 102 and 127 mm (4 and 5 in.). Sharp or jagged edgesshall be filed or honed to prevent snagging o
19、f the cleaningtissues during the mechanical cleaning process.5O-rings must be fluorosilicone polymer; consult Precision Associates, 742 N.Washington Ave., Minneapolis, MN 55401; Parker Seal Co., 10567 W. JeffersonBlvd., Culver City, CA 90230; availablefrom Keystone Aniline and Chemical Co., 321 N. L
20、oomis, Chicago, IL 60607.Cleaning Head, Brass Soiling Head, BrassMetric EquivalentsAB C D E F G Hin. 2145878316 15834316(mm) (57) (16) (22) (5) (25) (16) (19) (5)FIG. 1 Cleaning and Soiling HeadsC756 87 (2016)27.2 Twelve specimens are required to evaluate the cleanabil-ity index, that is, six of the
21、 candidate surface, and six of aporcelain enamel standard reference surface for cleanability.Porcelain enamel specimens are not damaged by the cleanabil-ity test and may be cleaned and reused many times. Specimenshave been reused as many as 50 times without damage or solidbuildup.NOTE 1The porcelain
22、 enamel covercoat used to coat the standardreference surface shall have the following characteristics: Acid Resis-tance: AA (Test Method C282) Alkali Resistance: Maximum 1.55 mg/cmwt. loss (Test Method C614).8. Preparation of Standard Soil8.1 The soiling agent shall consist of the following:Ingredie
23、nt Weight %Polyethylene glycol 98Keco Acid Black B 1Uranine, water-soluble 18.2 The uranine shall be added to the polyethylene glycol infood blender and mixed by alternate periods of mixing andstanding until the crystalline uranine appears to be completelydissolved in the glycol. The black dye which
24、 obscures all elseshall be added last and thoroughly mixed in the blender. Thissoiling agent shall be stored in a tightly stoppered glass bottleat least overnight before use.9. Procedure9.1 Specimen PretreatmentScrub the specimens with acellulose sponge wet with a 1 % solution of a mild householddet
25、ergent at room temperature. Rinse in turn with tap water,distilled water, and ethyl alcohol, and allow to dry in anear-vertical position at room temperature. Store the washedand dried specimens overnight in a desiccator charged with asaturated solution of potassium carbonate.9.2 Conditioning of Clea
26、ning TissuesCut a supply oftissues ample for use in specimen cleaning treatment in thefollowing paragraph into approximately 102-mm (4-in.)squares and store overnight, before use, in a desiccator chargedwith a saturated solution of potassium carbonate (relativehumidity approximately 45 %). Allow the
27、 tissues to remain inthe desiccator until just prior to use.Metric EquivalentsABCDEFGHIin.11618164 212 11458116 178 218(mm.) (1.6) (3.2) (0.4) (64) (32) (16) (1.6) (47) (54)All surfaces to be plated with bright nickel.FIG. 2 Brass Extraction CellC756 87 (2016)39.3 Soiling and Cleaning Treatments:9.3
28、.1 Lay out six specimens face up on a table. Homogenizethe soiling agent by up-ending several times before use. Fill thehypodermic syringe with no needle attached with the soilingagent by withdrawing the plunger. Expel this charge of soilback into the soil bottle. Then fill the syringe again. Wipe t
29、hetip of the syringe with a cleaning tissue and expel several dropsinto the soil bottle. Then, without rewiping the tip, hold thesyringe vertically over a specimen and discharge one drop nearthe center of each of the six specimens. Center the firstspecimen on the lapping wheel and hold it in place b
30、y meansof adhesive tape across the specimen corners. Place thepolytetrafluoroethylene-faced soiling head on the soil, andengage the spindle (Fig. 4) of the polishing unit. Operate thelapping wheel and the polishing unit for 1 min to distribute thesoil over the central portion of the specimen (Fig. 5
31、). Removethe soiling head and clean it with tissue for reuse. Adjust thespindle so that it rests over the center of the soil spot. Preparetwo cleaning heads 57 mm (214 in.) diameter) by covering withfour thicknesses of cleaning tissues clamped smoothly in place.With the repeating pipet expel exactly
32、 0.021 mL of distilledwater at the center of the tissue on the first cleaning head.9.3.2 Immediately place the cleaning head with tissue sideagainst the soiled specimen, engage the spindle, and operate for22 s (so that it will stop as well as start at the center of thespecimen). Remove the cleaning
33、head without sliding motion.Repeat the cleaning operation with the second tissue-coveredhead, using the same amount of distilled water and for the same22-s period.9.3.3 Store the first soiled and cleaned specimen in a nearvertical position in a rack while applying exactly the sameseries of soiling a
34、nd cleaning treatments to the five remainingspecimens.9.4 Water Extraction of the Soil RetainedRemove thesmall, often nonvisible, amounts of soil from the centralportion of the soiled and cleaned specimens with 10 mL ofdistilled water in the O-ring sealed extraction cell by thefollowing sequence of
35、operations within 30 min after soiling;place the first soiled and cleaned specimen, face up, in thecenter of the cell clamping frame. Place a clean and dryextraction cell (Fig. 2) on the center of the specimen so that theO-ring defines the area to be extracted (Fig. 5). Clamp the cellin the frame wi
36、th a light pressure from the wing nuts; introduce10 mL of distilled water with the 10-mL repeating pipet, swirlthe water in the cell momentarily and let stand for 3 min, givethe solution in the cell another swirl and pour out into a cleanand dry 100 mL beaker; transfer a portion of the extract to aM
37、etric EquivalentsABCDEFGHI JKLMNin.116 214 13814 178516 56114 31414 458 458 5(mm) (1.6) (64) (35) (6.4) (47) (8) (127) (152) (32) (83) (6.4) (117) (117) (127)FIG. 3 Device for Clamping Extraction Cell to SpecimenC756 87 (2016)4clean, dry cuvette and place the cuvette in a rack until the otherfive ex
38、tracts are ready for measurement in the fluorometer.9.5 Measurement of FluorescenceOperate the fluorometeraccording to the manufacturers instructions. Measure andMetric EquivalentsABCin. 101214(mm.) (254) (13) (6.4)FIG. 4 Spindle for PolisherFIG. 5 Equipment Used in Soiling and Cleaning SpecimensC75
39、6 87 (2016)5record the fluorescence of a distilled water blank. Measure andrecord in turn the fluorescence of the solutions extracted fromthe specimens.NOTE 2If concentrated solutions give off-scale readings, a 0.9neutral-density filter should be inserted between the fluorescing solutionand the phot
40、omultiplier. This filter transmits only 12.5 % of the lightemitted by the solution, reducing the fluroescence readings and bringingthem on scale. Redetermine the blank reading with the filter in place andmultiply the reduced reading by 8.0 which is 1 divided by the 12.5 %transmission of the neutral
41、density filter.9.6 Standard Reference SurfaceApply the test procedureoutlined in 7.1 through 7.5 to the Standard Reference Surfacesat least once during each testing day to obtain the averagefluorescence of solutions extracted from these specimens.9.7 Preferred Methods of Equipment Cleaning:9.7.1 The
42、 successful use of the fluorimetric analytical tech-niques employed in this procedure demands that a scrupulouslevel of cleanliness be maintained throughout. An oily thumb-print on the glass cuvette containing the solution to bemeasured may be more fluorescent than the unknown.9.7.2 Wash the glass b
43、eakers and the extraction cells beforeand after use by brushing in a warm detergent solution; rinsecopiously with flowing tap water and then with distilled water.The glass beakers may be oven dried. The extraction cells,without O-ring removal, may be wiped dry with clean tissue.Clean the syringe use
44、d for dispensing uniform amounts of soilon the specimens immediately following use with tap water,distilled water and alcohol, and dry the parts with tissue. Givethe glass cuvettes used for measuring fluorescent solutionsseveral rinses with tap water and then alcohol, and allow todrain in an inverte
45、d position in a holding rack. Discard thetissue for wiping glassware and other equipment after one use.10. Calculation of a Cleanability Index10.1 Subtract the measured fluorescence value for the dis-tilled water blank from the measured fluorescence value foreach of the six test surfaces and the six
46、 standard referencesurfaces. This will result in corrected fluorescence values forthe six test surfaces and for the six standard reference surfaces.10.2 Calculate the average of the corrected fluorescencevalues for the six test surfaces and for the six standardreference surfaces.10.3 Calculate the c
47、oefficient of variation of the correctedfluorescence values for the six test surfaces and for the sixstandard reference surfaces.10.4 Repeat the cleanability determinations on all six speci-mens (either the test specimens or the six standard referencespecimens) if the coefficient of variation is gre
48、ater than 20 %.10.5 The cleanability index is calculated as follows:CI 5 Ft/Fr (1)where:CI = the cleanability index of the surface being tested,Ft = the average corrected fluorescence of the test surfacesas calculated in 10.2, andFr = the average corrected fluorescence of the standardreference surfa
49、ces as calculated in 10.3.10.6 The method of calculation is shown in theAppendixes.11. Precision and Bias11.1 The precision of this test method, when performed bythe same operator in the same laboratory, should be sufficientso that the cleanability determination on six standard refer-ences should show a coefficient of variation no greater than20 %. No standard is available by which the bias of the testmethod can be determined.APPENDIXES(Nonmandatory Information)X1. INITIAL CALCULATIONSX1.1 The four calculations necessary on the data
