1、Designation: D 5007 99 (Reapproved 2003)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 Standard Environment for Condi-tioning and Testing Paint, Varnish, Lacquers, and RelatedMaterials3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 hiding index, hSthe Spreading Index at a standardfilm opacity. In this test method the latter i
6、s a visual contraststandard prepared by applying a semi-opaque white coating ona black and white hiding-power chart to give a contrast ratio of0.98 (98 %) which is just short of complete hiding, and is theconventional so-called full hiding end point in photometrichiding-power methods such as Test Me
7、thod D 2805. Refer tothe hiding indices of the wet and dry films as hSWand hSDrespectively.3.1.1.1 DiscussionSince this test method is intended tomeasure hiding-power difference rather than hiding poweritself, a 0.98 (98 %) contrast ratio standard is not required. It isnecessary only that the same s
8、tandard be used for measuringboth wet and dry films. See 3.1.8. For this purpose the standardneeds to lie within the contrast range of both the wet and drystripes, which is true of the 0.98 (98 %) contrast-ratio standardfor most commercial paints. With paints of unusually lowhiding, a lower contrast
9、 standard may be required, which canbe simply one of the stripes taken from a drawdown of the testpaint.3.1.2 hiding powerthe 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 Discuss
10、ionIn 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 describe
11、d as “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 logicatora multi-notch applicator with clearances,and corresponding wet film thicknesses
12、and spreading rates, inequal percentage steps.3.1.4 logicator scalea scale with values directly related tothe logarithms of corresponding spreading rates. A specifiedchange in scale value represents the same percentage change inspreading rate over any part of such a scale.3.1.5 spreading index, hthe
13、 spreading rate expressed inlogicator scale units (LU) as described in 3.1.4 and 3.1.7.3.1.6 spreading rate, Hthe area covered per unit quantityof coating. (In this test method the quantity is volumetric).3.1.7 TG19 logicatora logicator designed for this testmethod with eight notches numbered at fou
14、r-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 film thick-nesses from 37 to 145 m (1.46 to 5.7 mils) and spreading ratesfrom 6.9 to 27 m2/L (280 to 1100 ft2/gal), with one scale unitrepresenting a change of 5 % and the
15、four-unit interval betweennotches a cumulative change of 21.55 % in the clearance and1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.42 on Architectural Coatings.Current ed
16、ition approved Dec. 1, 2003. Published December 2003. Originallyapproved in 1989. Last previous edition approved in 1999 as D 5007 99.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume info
17、rmation, 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.corresponding film thicknesses and spreading rates. Refer tothis scale unit as a logicator unit (LU). (See Fig.
18、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 detailed relationships between scalar value andthe n
19、otch clearance, wet film thickness, and spreading rate aregiven in Table 1 and Table 2.3.1.8 wet-to-dry hiding change (WDHC)the difference inthe Hiding Index of a paint between the wet and the dry state,expressed in logicator units (LU) as follows:WDHC 5DhS5 hSD2 hSW(1)3.1.8.1 DiscussionThe WDHC is
20、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 estimated film thickness/clearance ratio T/N (seeNote 1,
21、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 with an agreed hiding standardimmediately after applic
22、ation 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 isrecorded as the wet-to-dry hiding change WDHC.4.4 If des
23、ired, 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. Anincrease in hiding is sometimes associated with porosity a
24、ndpoor 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 specifications andas a short, simple procedure for evaluation
25、 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 and scale numbers printed at thetop corresponding to t
26、he 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 hadbeen applied to obtain a contrast ratio of 0.98. The strip
27、e 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 this test methodusing standards prepared with the self
28、-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-tempted anyway, it is of interest to note that the whi
29、te 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.7.3 Spread about 6 mL of the test paint evenly in front of thelogic
30、ator, 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 Index (hs):3The sole source of
31、 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 meeting of t
32、heresponsible 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 FilmThickn
33、ess, 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= 27.6
34、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 (2003)27.5.1 Place the chart vertically in a well-
35、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 decidewhich of two adjacent stripes is matched more closely,
36、 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 after determining the Wet Hiding Index(hSW), place the d
37、rawdown 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 meanindex value to 0.1 units. Individual values that deviate f
38、rom 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 value for WDHC is positive for an increase and negativ
39、efor 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. Report9.1 Report the following information:9.1.1 The Wet-t
40、o-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 study of this test method, twooperators in each of two
41、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 standard deviation was 0.77 LU with 85 dfand the interl
42、aboratory 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 replicates by thesame operator should be considered suspec
43、t 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 discarded on thefollowing basis: (1) all results from on
44、e 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 (3) all threeresults from the same laboratory for anoth
45、er 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.11. Keywords11.1 hiding power; wet-to-dry hiding change5Supporting data are available fro
46、m ASTM International Headquarters. RequestRR: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 mils m ft2/gal m2/L20 10.40 264 5.72 145 28
47、0 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 55 744 18.325 8.15 207 4.48 114 358 8.78 41
48、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 6.38 162 3.51 89 457 11.2 46 2.93 74 1.61 41 99
49、7 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 (2003)3NOTE 1For illustration only. Shading is not accurate.FIG. 2 Logicator Test ApplicationD 5007 99 (2003)4ASTM International takes no position respecting the
