1、Designation: D344 11Standard Test Method forRelative Hiding Power of Paints by the Visual Evaluation ofBrushouts1This standard is issued under the fixed designation D344; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、last revision. 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 test method provides for the qualitative and quan-titative visual determination of the hiding power of a test pai
3、ntrelative 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 asstandard. No other units of measurement are inclu
4、ded in thisstandard.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 regulatory limitations prior to
5、 use.2. Referenced Documents2.1 ASTM Standards:2D16 Terminology for Paint, Related Coatings, Materials,and ApplicationsD1475 Test Method For Density of Liquid Coatings, Inks,and Related ProductsD1729 Practice for Visual Appraisal of Colors and ColorDifferences of Diffusely-Illuminated Opaque Materia
6、lsD2805 Test Method for Hiding Power of Paints by Reflec-tometryD5068 Practice for Preparation of Paint Brushes for Evalu-ationE1247 Practice for Detecting Fluorescence in Object-ColorSpecimens by SpectrophotometryE1347 Test Method for Color and Color-Difference Mea-surement by Tristimulus Colorimet
7、ryE1349 Test Method for Reflectance Factor and Color bySpectrophotometry Using Bidirectional (45:0 or 0:45)Geometry3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this test method, referto Terminology D16 and the Paint/Coatings Dictionary.33.2 Definitions of Terms Specific to Th
8、is Standard:3.2.1 relative hiding power, qualitative, nthe characteriza-tion of a test paint as being better, equal, or poorer in hidingpower than a comparison paint.3.2.2 relative hiding power, quantitative, nthe spreadingrate of a paint expressed as a percent of the spreading rate ofa comparison p
9、aint 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 the substrate c
10、ontrast.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 to a compariso
11、n 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 application procedur
12、e 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 likewise give
13、 different results.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.26 on Optical Properties.Current edition approved June 1, 2011. Published June 2011. Originallyapproved i
14、n 1932. Last previous edition approved in 2004 as D344 97 (2004).DOI: 10.1520/D0344-11.2For referenced ASTM standards, 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 Summar
15、y page onthe ASTM website.3Available from Federation of Societies for Coatings Technology (FSCT), 492Norristown Rd., Blue Bell, PA 19422-2350, http:/www.coatingstech.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.NOTE 1Test Meth
16、od D2805 describes an instrumental method forquantitatively determining hiding power without reference to a materialpaint standard. The paint film is applied at a uniform thickness (forexample, with a doctor blade), the film thickness is measured rigorously,and the opacity is evaluated photometrical
17、ly. Hiding power is therebydetermined with a high degree of precision.5.3 Test Method D344 is less precise than Test MethodD2805, 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 la
18、boratory balance having a capac-ity of 100 g and sensitivity of 0.1 g.6.2 Syringe, 10-mL capacity.6.3 Paint Brush, ferrule 50 mm wide and 14 mm thick,tapered polyester filaments 70 mm long with flagged chiseltrim tip.46.4 Container, 250-mL beaker.6.5 Test Surface, a smooth-surfaced paper chart havin
19、gadjacent 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
20、E1347 or E1349. 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 areasma
21、y be used if available, with appropriate modification of theindicated calculations.6.6 Illumination, a light source providing diffuse light ofreasonable intensity, preferably northern sky light or an ap-proximation of same. (See Practice D1729).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. In any case,the spreading rate shall not be so low that the substrate contrastis difficult to see, nor so high that it is difficult to apply the paintat a re
23、asonably uniform film thickness.7.2 Determine the density D in grams per millilitre of thecomparisons and test paints, in accordance with Test MethodD1475.7.3 Calculate to three significant figures the volume V inmillilitres to apply for the selected spreading rate SR asfollows:VmL! 5100SRm2/L!(1)7.
24、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 stir the paint well. Thenprecondition the brush by dipping it into the paint and workingit out on a smooth, nonporous surface as described
25、in PracticeD5068. 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, distribute the paint evenly over thetest area of the chart, then brush the paint out uniformly withinthe test area. Set the brushout aside
26、 to dry in a horizontalposition, protected adequately from dust and under normalroom conditions of ventilation and temperature. Reweigh theempty syringe with the brush and container. The loss of weightrepresents the actual weight of paint applied to the test surfaceas opposed to the intended weight
27、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 brushout. Instead, calculate the actual spreadingrate as follows:SRA5BA3 SRB(2)where:SRA= actual spreading rate,B = intended weight,A = actual w
28、eight, andSRB= intended spreading rate.8. Evaluation Procedure8.1 Viewing conditionsWhen the test and comparisonpaint brushouts are thoroughly dry, place them vertically sideby side against a flat surface and view them from a distance of1.5 to 3 m under illumination conditions as described in 6.6.8.
29、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 of the comparison paint brushout, then the hiding power ofthe test paint is considered as better than, equal to, or poorerthan that of the comp
30、arison 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 brushout with either paint so as toeliminate the difference, then compare again to confirm orrevise the previous estimation of relative hiding po
31、wer.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 series of additional comparison paint brushouts at severalother spreading rates, differing in steps of approximately 15 %and providing contrasts
32、 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 viewingconditions d
33、escribed in 8.1 to assure that this is the case.4Describes the brush used by the round-robin participants. Other 50-mm brushesof equivalent quality may be used, no doubt with similar results. Ideally, the sametype of brush should be used within a comparison set, and among correspondentlaboratories.5
34、As observed visually under ultraviolet illumination or determined in accor-dance with Practice E1247.D344 1128.3.2 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
35、standards it is intermediate. In the latter 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 diffe
36、rence between the two standards to the nearestfourth. 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) o
37、f the comparisonpaint at which it is estimated 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
38、 contrast rating of the test paint brushout.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 comp
39、arison paint at equalhiding, as determined 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 t
40、hecomparison paint. The report may be amplified 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
41、 square feet pergallon or square metres per 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 occ
42、urred with apaint that was apparently very 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 interlaborat
43、ory study of thismethod, four coatings were 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
44、 one laboratory were asvariable as those from 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 accep
45、tability of results at the 95 %confidence 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 p
46、recision could not be obtained because only 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
47、 Robin Results of Relative Hiding Power of 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
48、 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.D344 113ASTM International takes no position respecting the validity of any patent rights asserted in connection with any i
49、tem 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 technical 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 wi
