1、Designation: D 344 97 (Reapproved 2004)Standard Test Method forRelative Hiding Power of Paints by the Visual Evaluation ofBrushouts1This standard is issued under the fixed designation D 344; the number immediately following the designation indicates the year oforiginal adoption or, in the case of re
2、vision, 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.1. Scope1.1 This test method provides for the qualitative and quan-titative visual determination of the hidin
3、g power of a test paintrelative to that of a comparison paint.1.2 This test method describes only a brushout applicationprocedure in specific detail, but its concepts are valid for othermethods of application as well.1.3 The values stated in SI units are to be regarded as thestandard. The values giv
4、en in parentheses are for informationonly.1.4 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 appro-priate safety and health practices and determine the applica-bility of regulator
5、y limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 16 Terminology for Paint, Related Coatings, Materials,and ApplicationsD 1475 Test Method for Liquid Coatings, Inks, and RelatedProductsD 1729 Practice for Visual Appraisal of Colors and ColorDifferences of Diffusely-Illuminated
6、Opaque MaterialsD 2805 Test Method for Hiding Power of Paints by Reflec-tometryD 5068 Practice for Preparation of Paint Brushes for Evalu-ationE 1247 Practice for Detecting Fluorescence in Objective-Color Specimens by SpectrophotometryE 1347 Test Method for Color and Color-Difference Mea-surement by
7、 Tristimulus (Filter) ColorimetryE 1349 Test Method for Reflectance Factor and Color bySpectrophotometry Using Bidirectional Geometry3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this test method, referto Terminology D 16 and the Paint/Coatings Dictionary.33.2 Definitions of T
8、erms Specific to This Standard:3.2.1 relative hiding power, qualitativethe characteriza-tion of a test paint as being better, equal, or poorer in hidingpower than a comparison paint.3.2.2 relative hiding power, quantitativethe spreading rateof a paint expressed as a percent of the spreading rate of
9、acomparison paint at equal hiding.4. Summary of Test Method4.1 QualitativeThe test and comparison paints arebrushed out uniformly at the same spreading rate on black andwhite hiding power charts. After drying the brushouts arecompared visually to see which paint has been most effectivein reducing th
10、e substrate contrast.4.2 QuantitativeAdditional brushouts are made with thecomparison paint, if and as necessary, to determine the spread-ing rate at which it matches the hiding of the test paintbrushout.5. Significance and Use5.1 This test method evaluates the hiding power of a testpaint relative t
11、o a comparison paint. The results have signifi-cance only within that relationship. It may be used forproduction control or quality comparisons.5.2 When a paint is applied by brush or any other practicalmethod, the opacity of the film is affected by variations in filmthickness related to the applica
12、tion procedure and to theapplication characteristics of the paint. Two paints that hideequally well by this method might therefore differ considerablywhen applied with a doctor blade, since the latter method givesessentially perfect leveling. Different brushes or surface appli-cation conditions can
13、likewise give different results.NOTE 1Test Method D 2805 describes an instrumental method forquantitatively determining hiding power without reference to a materialpaint standard. The paint film is applied at a uniform thickness (for1This test method is under the jurisdiction of ASTM Committee D01 o
14、n Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.26 on Optical Properties.Current edition approved Nov. 1, 2004. Published November 2004. Originallyapproved in 1932. Last previous edition approved in 1997 as D 344 97.2For referenced ASTM st
15、andards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Published by the Federation of Societies for Coatings Technology, 492Norristown Rd.
16、, Blue Bell, PA 19422.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.example, with a doctor blade), the film thickness is measured rigorously,and the opacity is evaluated photometrically. Hiding power is therebydetermined with a hig
17、h degree of precision.5.3 Test Method D 344 is less precise than Test MethodD 2805, but is more practical because it is responsive to theapplication characteristics of paints, and is simpler in conceptand execution.6. Apparatus6.1 Balance, top-loading laboratory balance having a capac-ity of 100 g a
18、nd sensitivity of 0.1 g.6.2 Syringe, 10-mL capacity.6.3 Paint Brush, ferrule 50 mm (2 in.) wide and 14 mm (916in.) thick, tapered polyester filaments 70 mm (234 in.) longwith flagged chisel trim tip.46.4 Container,12-pint can or 250-mL beaker.6.5 Test Surface, a smooth-surfaced paper chart havingadj
19、acent black and white areas and coated with a suitablevarnish or lacquer so as to render the surface impervious topaint liquids. The black and white areas of the chart shall haveluminous reflectance factors of 1 % maximum and 75 %minimum, respectively, when tested in accordance with TestMethods E 13
20、47 or E 1349. The white areas of the charts usedin any one testing program shall not differ in their reflectancefactors by more than 1 %, and shall be nonfluorescent.5Anysuitable regular design of contrasting areas may be used. Thechart shall have a defined test area of 0.1 m2. Larger test areasmay
21、be used if available, with appropriate modification of theindicated calculations.66.6 Illumination, a light source providing diffuse light ofreasonable intensity, preferably northern sky light or an ap-proximation of same. (See Practice D 1729).7. Preparation of Brushouts7.1 Select a convenient and
22、suitable spreading rate, mutu-ally agreeable to all parties involved in the testing program,and preferably in the range from 9.8 to 19.6 m2/L (400 to 800ft2/gal). In any case, the spreading rate shall not be so low thatthe substrate contrast is difficult to see, nor so high that it isdifficult to ap
23、ply the paint at a reasonably uniform filmthickness.NOTE 2The gallon unit referred to here and throughout this testmethod is the U.S. gallon (3785.4 mL).7.2 Determine the density D in grams per millilitre of thecomparisons and test paints, in accordance with Test MethodD 1475.7.3 Calculate to three
24、significant figures the volume V inmillilitres to apply for the selected spreading rate SR asfollows:VmL! 5100SRm2/L!54074.6SRft2/gal!(1)7.4 Calculate to three significant figures, the weight W ingrams corresponding to the volume V (mL) as follows:Wg! 5 VmL! 3 Dg/mL!7.5 To prepare a brushout, first
25、stir the paint well. Thenprecondition the brush by dipping it into the paint and workingit out on a smooth, nonporous surface as described in PracticeD 5068. Take up the desired volume of paint in the syringe andweigh it with the brush in the empty container. Place the testchart on a level bench top
26、, distribute the paint evenly over thetest area of the chart, then brush the paint out uniformly withinthe test area. Set the brushout aside to dry in a horizontalposition, protected adequately from dust and under normalroom conditions of ventilation and temperature. Reweigh theempty syringe with th
27、e brush and container. The loss of weightrepresents the actual weight of paint applied to the test surfaceas opposed to the intended weight calculated from 7.3 and 7.4.If there is a discrepancy do not attempt to correct it byremoving or applying paint since this would disturb theleveling of the brus
28、hout. Instead, calculate the actual spreadingrate as follows:SRA5BA3 SRB(2)where:SRA= actual spreading rate,B = intended weight,A = actual weight, andSRB= intended spreading rate.8. Evaluation Procedure8.1 Viewing conditionsWhen the test and comparisonpaint brushouts are thoroughly dry, place them v
29、ertically sideby side against a flat surface and view them from a distance of1.5to3m(5to10ft)under illumination conditions asdescribed in 6.6.8.2 Qualitative Evaluation:8.2.1 If the contrast between the black and white areas of thetest paint brushout is adjudged less than, equal to, or more thanthat
30、 of the comparison paint brushout, then the hiding power ofthe test paint is considered as better than, equal to, or poorerthan that of the comparison paint.8.2.2 If the actual spreading rate of the lower contrastpaint-out is lower than that of the other paint-out by more than3 %, prepare a second b
31、rushout with either paint so as toeliminate the difference, then compare again to confirm orrevise the previous estimation of relative hiding power.8.3 Quantitative Evaluation:8.3.1 If the hiding of the test paint brushout does not matchthat of the comparison paint at the same spreading rate, makea
32、series of additional comparison paint brushouts at several4Describes the brush used by the round-robin participants. Other 50-mm (2 in )brushes of equivalent quality may be used, no doubt with similar results. Ideally, thesame type of brush should be used within a comparison set, and among correspon
33、-dent laboratories.5As observed visually under ultraviolet illumination or determined in accor-dance with Practice E 1247.6The only manufacturing source of charts known to be in compliance with 6.5and suitable for this test method is Leneta Company, 15 Whitney Rd., Mahwah, NJ07430. If you are aware
34、of alternative suppliers, please provide this information toASTM International Headquarters. Your comments will receive careful consider-ation at a meeting of the responsible technical committee,1which you may attend.D 344 97 (2004)2other spreading rates, differing in steps of approximately 15 %and
35、providing contrasts above and below that of the test paintbrushout. Refer to these and to the original comparison paintbrushout as standards. If the standards are prepared correctly,each increase in spreading rate will correspond to a perceptibleincrease in contrast. Compare the standards under the
36、viewingconditions described in 8.1 to assure that this is the case.8.3.2 Compare the brushout of the test paint with thestandards under the specified viewing conditions to determinewhich standard it matches in contrast, or if none to which pairof successive standards it is intermediate. In the latte
37、r caseview the test paint brushout with the two standards on eitherside and rate the contrast of the test paint brushout byestimating the contrast difference between it and the lowerspreading rate (lower contrast) standard, as a fraction of thecontrast difference between the two standards to the nea
38、restfourth. Keeping the test paint brushout in the middle, reversethe position of the two standards and rate the test paintbrushout again in the same way. The final rating is the mean ofthe two to the nearest eighth.8.3.3 Calculate the spreading rate (SRC) of the comparisonpaint at which it is estim
39、ated to match the hiding of the testpaint brushout as follows:SRC5 SR11 XSR22 SR1! (3)where:SR1= spreading rate of the lower spreading rate (lowercontrast) standard,SR2= spreading rate of the higher spreading rate (highercontrast) standard, andX = fractional contrast rating of the test paint brushou
40、t.8.3.4 Calculate the relative hiding power of the test paint inaccordance with the definition in 3.2.2 as follows:HPt5SRtSRc3 100 (4)where:HPt= relative hiding power of the test paint,SRt= spreading rate of the test paint, andSRc= spreading rate of the comparison paint at equalhiding, as determined
41、 by an actual match with one ofthe standards or by estimation between two stan-dards as described and calculated in 8.3.2 and 8.3.3.9. Report9.1 Qualitative (see 8.2)Report the relative hiding powerof the test paint as better than, equal to, or poorer than thecomparison paint. The report may be ampl
42、ified by such termsas exactly, slightly, moderately, considerably, etc., as may seemappropriate.9.2 Quantitative (see 8.3)Report the relative hidingpower of the test coating to the nearest whole number. This isa purely numerical value. Physical units such as square feet pergallon or square metres pe
43、r litre are not applicable.10. Precision10.1 QualitativeFour test paints were rated versus acomparison paint by three laboratories, twice each by onelaboratory and once each by the other two, for a total of 16trials. There was only one discrepancy, which occurred with apaint that was apparently very
44、 similar in hiding power to thecomparison paint. These results indicate that the method iseffective, but more results would be required to develop a moredetailed precision statement. Table 1 gives the results of thesetests.10.2 QuantitativeIn an interlaboratory study of thismethod, four coatings wer
45、e evaluated for hiding power againsta fifth coating taken as the standard. In one laboratory eachmaterial was tested twice, but only once in the other twolaboratories. Statistical analysis of the results revealed that thetwo results for each coating from the one laboratory were asvariable as those f
46、rom the other two. Consequently, the tworesults were treated as being individual results and the inter-laboratory standard deviation was found to be 10 % with 12 df.Based on this standard deviation, the following criterion shouldbe used for judging the acceptability of results at the 95 %confidence
47、level:10.2.1 ReproducibilityTwo single results obtained by op-erators in different laboratories should be considered suspect ifthey differ in relative hiding power by more than 32 % of theirmean.10.2.2 RepeatabilityA reasonable estimate of intralabora-tory precision could not be obtained because onl
48、y one labora-tory repeated the test.10.3 BiasThe concept of bias is not applicable to this testmethod because its measurements are comparative, and there isno objective true reference value.11. Keywords11.1 hiding power; opacity; relative hidingTABLE 1 Round Robin Results of Relative Hiding Power of
49、 FourWhite Paints versus a Comparison White PaintMethod PaintLaboratory 1Laboratory2Laboratory3Trial 1 Trial 2Qualitative V1AA A AV2BV3CC C CV4V5AC C CQuantitative V1 125 117 115 120V2B100 100 100 100V3 85 93 62 96V4 66 82 60 67V5 102 90 83 95AIndicates that the test paint hides better than the comparison paint.BComparison paint, relative hiding power equals 100.CIndicates that the test paint hides poorer than the comparison paint.D 344 97 (2004)3ASTM International takes no position respecting the validity of any patent rights asserted in connection with any
