1、Designation: D 5007 99 (Reapproved 2008)Standard Test Method forWet-to-Dry Hiding Change1This standard is issued under the fixed designation D 5007; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A numbe
2、r 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 covers the determination of the changein hiding power of an architectural coating during drying, byvisual evaluation of th
3、e wet and dry film.1.2 This test method is not recommended for colors otherthan white and tints.1.3 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.4 This standard does not purport to address all of thesafety concerns, if any
4、 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. Referenced Documents2.1 ASTM Standards:2D 2805 Test Method for Hiding Power of Paints by Re
5、flec-tometryD 3924 Specification for Environment for Conditioning andTesting Paint, Varnish, Lacquer, and Related Materials3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 hiding index (hS), nthe Spreading Index at a stan-dard film opacity.3.1.1.1 DiscussionIn this test method
6、the latter is a visualcontrast standard prepared by applying a semi-opaque whitecoating on a black and white hiding-power chart to give acontrast ratio of 0.98 (98 %) which is just short of completehiding, and is the conventional so-called full hiding end pointin photometric hiding-power methods suc
7、h as Test MethodD 2805. Refer to the hiding indices of the wet and dry films ashSWand hSDrespectively.Since this test method is intended to measure hiding-powerdifference rather than hiding power itself, a 0.98 (98 %)contrast ratio standard is not required. It is necessary only thatthe same standard
8、 be used for measuring both wet and dryfilms. See 3.1.8. For this purpose the standard needs to liewithin the contrast range of both the wet and dry stripes, whichis true of the 0.98 (98 %) contrast-ratio standard for mostcommercial paints. With paints of unusually low hiding, alower contrast standa
9、rd may be required, which can be simplyone of the stripes taken from a drawdown of the test paint.3.1.2 hiding power, nthe spreading rate of a paint applieduniformly on a standard black and white hiding power chart togive a standard degree of contrast just short of complete hiding.3.1.2.1 Discussion
10、In reflectometry the standard contrastfor hiding power measurements is generally accepted as thecontrast ratio C = 0.98 (98 %), which with white and lighttinted coatings is equivalent to a visual color difference ofabout 0.75 CIELAB units. That amount of color difference canreasonably be described a
11、s “just-short-of complete-hiding.”Since this is a visual method it employs a visual comparator asa standard, which is a hiding power chart with a white coatingapplied at a contrast ratio of 0.98 (98 %).3.1.3 logicator, na multi-notch applicator with clear-ances, and corresponding wet film thicknesse
12、s and spreadingrates, in equal percentage steps.3.1.4 logicator scale, na scale with values directly relatedto the logarithms of corresponding spreading rates.3.1.4.1 DiscussionA specified change in scale value rep-resents the same percentage change in spreading rate over anypart of such a scale.3.1
13、5 spreading index (h), nthe spreading rate expressedin logicator scale units (LU) as described in 3.1.4 and 3.1.7.3.1.6 spreading rate (H), nthe area covered per unitquantity of coating.3.1.6.1 DiscussionIn this test method the quantity isvolumetric.3.1.7 TG19 logicator, na logicator designed for t
14、his testmethod with eight notches numbered at four-unit intervals on ascale from 20 to 48, the notch clearances ranging from 67 to264 m (2.65 to 10.4 mils) corresponding to wet film1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, andApplicati
15、ons and is the direct responsibility ofSubcommittee D01.42 on Architectural Coatings.Current edition approved Feb. 1, 2008. Published February 2008. Originallyapproved in 1989. Last previous edition approved in 2003 as D 5007 99 (2003).2For referenced ASTM standards, visit the ASTM website, www.astm
16、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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.thicknesse
17、s from 37 to 145 m (1.46 to 5.7 mils) and spreadingrates from 6.9 to 27 m2/L (280 to 1100 ft2/gal), with one scaleunit representing a change of 5 % and the four-unit intervalbetween notches a cumulative change of 21.55 % in theclearance and corresponding film thicknesses and spreadingrates. Refer to
18、 this scale unit as a logicator unit (LU). (See Fig.1.)3.1.7.1 DiscussionThe percentage difference betweennotches is calculated as (1.0541)3 100 = 21.55. This per-centage is applicable precisely to the notch clearances andapproximately to their related wet-film thicknesses and spread-ing rates. The
19、detailed relationships between scalar value andthe notch clearance, wet film thickness, and spreading rate aregiven in Table 1 and Table 2.3.1.8 wet-to-dry hiding change (WDHC), nthe differencein the Hiding Index of a paint between the wet and the drystate, expressed in logicator units (LU) as follo
20、ws:WDHC 5DhS5 hSD2 hSW(1)3.1.8.1 DiscussionThe WDHC is unchanged if the con-trast level of the hiding standard is varied, because the resultantchanges in the two hiding power values are proportional andtheir ratio therefore constant.3.1.8.2 DiscussionThe WDHC is unaffected by devia-tions from the es
21、timated film thickness/clearance ratio T/N (seeNote 1, Table 1), because the ratio of the two recalculatedhiding-power values is unchanged.4. Summary of Test Method4.1 The test paint is applied with a TG19 Logicator on alogicator test chart (see 6.2 and Fig. 2) and the drawdownexamined in comparison
22、 with an agreed hiding standardimmediately after application and again after drying.4.2 The scale numbers of the wet and dry stripes that matchthe standard in contrast are recorded as the Wet Hiding Index,hSW, and the Dry Hiding Index hSD.4.3 The difference between the wet and dry hiding indices isr
23、ecorded as the wet-to-dry hiding change WDHC.4.4 If desired, the percent change in hiding power corre-sponding to the WDHC value is calculated and reported.5. Significance and Use5.1 Many architectural paints, particularly white and lighttints, change significantly in film opacity as they dry. Aninc
24、rease in hiding is sometimes associated with porosity andpoor film integrity with conventionally formulated coatings. Adecrease can result in a disappointing paint job. The wet-to-dryhiding change is therefore a property of great practical impor-tance.5.2 This test method can be used in paint specif
25、ications andas a short, simple procedure for evaluation and quality control.6. Apparatus6.1 TG19 Logicator3A multi-notch, varied-clearance ap-plicator designed specifically for this test method (see 3.1.7 andFig. 1).6.2 Logicator Test Charts3Black and white hiding chartswith a chevron-stripe pattern
26、 and scale numbers printed at thetop corresponding to the paint stripes applied by the Logicator(see Fig. 2).6.3 Vacuum Plate, for holding the chart flat while thedrawdown is made.6.4 Visual Hiding Standard4A narrow stripe cut from alogicator test chart on which a durable glossy white coating hadbee
27、n applied to obtain a contrast ratio of 0.98. The stripe ismounted on a blank card for convenient handling, as illustratedin Fig. 3.7. Procedure7.1 Prepare a hiding standard as described in 6.4, or use thestandard supplied with the logicator test charts.NOTE 1Strong colors were measured according to
28、 this test methodusing standards prepared with the self-same coatings. Some measurementswere also made using the regular white standard. Due to poor correlationin these tests it was decided to exclude strong colors from the scope of thetest method. However, should measurements with such colors be at
29、tempted anyway, it is of interest to note that the white standard apparentlyserved as well for that purpose as a standard made with the identical color.7.2 Place a test chart on the vacuum plate. Then place thelogicator at the top of the chart with its arms extending towardthe operator.3The sole so
30、urce of supply of logicator test charts known to the committee at thistime is the Leneta Company, 15 Whitney Rd., Mahwah, NJ 07430. If you are awareof alternative suppliers, please provide this information to ASTM InternationalHeadquarters. Your comments will receive careful consideration at a meeti
31、ng of theresponsible technical committee,1which you may attend.4A white standard of this description is supplied with the TG19 Logicator TestCharts.FIG. 1 Diagram of the Leneta TG19 LogicatorTABLE 1 Equations Relating the Logicator Scale Value orSpreading Index, h, to the Notch Clearance, N, Wet Fil
32、mThickness, T, and Spreading Rate, HNOTE 1The relationships involving T and H are based on a presumedT/N ratio of 0.55, which ratio is approximate and somewhat variable,depending on coating rheology, drawdown technique, and clearance.Inch-Pound Units(mils, ft2/gal):Metric Units(m, m2/L):N = 1.0568-h
33、 27.6 4 1.05hN = 25.4 3 1.0568-h= 701 4 1.05hh = 68 47.2 log Nh= 134.3 47.2 log NT = 0.55 N = 15.184 1.05hT = 0.55 N = 385.54 1.05hh = 55.75 47.2 log Th= 122.05 47.2 log TH = 105.7 3 1.05hH = 2.594 3 1.05hh = 47.2 log H 95.52 h = 47.2 log H 19.54D 5007 99 (2008)27.3 Spread about 6 mLof the test pai
34、nt evenly in front of thelogicator, then draw down the full length of the chart (about254 mm (10 in.) at a uniform speed such that the totaldrawdown time is about 2.5 to 3 s.7.4 Promptly after film application, determine the WetHiding Index (hSW) in accordance with 7.5.7.5 Observation of the Hiding
35、Index (hs):7.5.1 Place the chart vertically in a well-illuminated glare-free location.7.5.2 Hold the hiding standard next to the chart and identifyby number the stripe that the standard matches in contrast. Thisnumber is the Hiding Index.7.5.3 If there is no exact match and it is difficult to decide
36、which of two adjacent stripes is matched more closely, recordtheir mean as the Hiding Index. However, if the standard isperceived as closer to one or the other of the two stripes, thenreport the Hiding Index as one more than the lower or one lessthan the higher, as the case may be.7.6 Immediately af
37、ter determining the Wet Hiding Index(hSW), place the drawdown horizontally in a well-ventilated,dust-free location, as specified in Specification D 3924, andallow to dry for 40 to 48 h. Then repeat 7.5 to determine theDry Hiding Index (hSD).7.7 Make drawdowns in triplicate and calculate the meaninde
38、x value to 0.1 units. Individual values that deviate from themean by more than 1.5 units should be discarded and the testrepeated.8. Calculation8.1 Subtract the Wet Hiding Index, hSWfrom the DryHiding Index, hSDto obtain the wet-to-dry hiding change(WDHC), D hS, as follows:WDHC 5DhS5 hSD2 hSW(2)The
39、value for WDHC is positive for an increase and negativefor a decrease in hiding. To avoid possible misunderstandingwrite the sign of the change ( + or ) in every case.8.2 If desired, calculate the corresponding percent change inwet-to-dry hiding power as follows:WDHC% 5 1.05WDHC2 1! 3 100 (3)9. Repo
40、rt9.1 Report the following information:9.1.1 The Wet-to-Dry Hiding Change (WDHC) in logicatorunits (LU) to one decimal place, as described in 8.1, and9.2 If desired, the percent change in conventional hidingpower (WDHC%), calculated as shown in 8.2.10. Precision and Bias510.1 In an interlaboratory s
41、tudy of this test method, twooperators in each of two laboratories and one operator in eachof six laboratories, tested in triplicate five coatings with a widerange in wet-to-dry hiding change. Since the test was notrepeated the repeatability is only for replicates. On this basisthe intralaboratory s
42、tandard deviation was 0.77 LU with 85 dfand the interlaboratory standard deviation was 1.97 LU with 39df. See Note 2. Based on these standard deviations thefollowing criteria should be used for judging the acceptabilityof results at the 95% confidence level:10.1.1 Repeatability (Replicate)Three repl
43、icates by thesame operator should be considered suspect if they differ bymore than 2.6 LU.10.1.2 ReproducibilityTwo results, each the mean of trip-licates, obtained by different operators should be consideredsuspect if they differ by more than 5.7 LU.NOTE 2In the statistical analysis results were di
44、scarded on thefollowing basis: (1) all results from one operator who appeared to be lesssensitive than the other operators in detecting differences among tripli-cates, (2) one replicate result from one laboratory because the triplicaterange was significantly higher than for other laboratories, and (
45、3) all threeresults from the same laboratory for another paint because the meandiffered significantly from other means for that paint.10.2 BiasThis test method has no bias because there is nocriterion for the measured property more valid than the testmethod itself.5Supporting data have been filed at
46、 ASTM International Headquarters and maybe obtained by requesting Research Report RR:D011063.TABLE 2 Logicator Scale Relationships Calculated from Equations in Table 1IndexAClearance Film ThicknessBSpreading RateBIndexAClearance Film ThicknessBSpreading RateBh milsCm mils m ft2/gal m2/L h milsCm mil
47、s m ft2/gal m2/L20 10.40 264 5.72 145 280 6.88 36 4.76 121 2.62 67 612 15.021 9.90 252 5.44 138 294 7.23 37 4.54 115 2.50 63 643 15.822 9.43 240 5.19 132 309 7.59 38 4.32 110 2.38 60 675 16.623 8.98 228 4.94 126 325 7.97 39 4.12 105 2.26 58 709 17.424 8.56 217 4.71 120 341 8.37 40 3.92 100 2.16 55 7
48、44 18.325 8.15 207 4.48 114 358 8.78 41 3.73 95 2.05 52 781 19.226 7.76 197 4.27 108 376 9.22 42 3.56 90 1.96 50 820 20.127 7.39 188 4.07 103 395 9.68 43 3.38 86 1.86 47 861 21.128 7.04 179 3.87 98 414 10.2 44 3.23 82 1.77 45 904 22.229 6.70 170 3.69 94 435 10.7 45 3.07 78 1.69 43 950 23.330 6.38 16
49、2 3.51 89 457 11.2 46 2.93 74 1.61 41 997 24.531 6.08 154 3.34 85 480 11.8 47 2.79 71 1.53 39 1047 25.732 5.79 147 3.19 81 504 12.4 48 2.65 67 1.46 37 1100 27.033 5.52 140 3.03 77 529 13.034 5.25 133 2.89 73 555 13.635 5.00 127 2.75 70 583 14.3ABoldface values refer to notches in TG19 Logicator.BBased on wet film thickness estimated at 55 % of clearance.CTarget values are significant to one decimal place.D 5007 99 (2008)3NOTE 1For illustration only. Shading is not accurate.FIG. 2 Logicator Test ApplicationD 5007 99 (2008)411. Ke
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