ASTM C954-15 pdf download.Standard Test Method for Hiding Power of Paints by Reflectometry.
4. Summary of Test Method 4.1 The reflectivity R ∞ of the coating is determined from reflectance measurements on black and white hiding power charts. 4.2 The scattering coefficient S of the coating is determined from R ∞ , and the reflectance R 0 and spreading rate H X ofa film applied on black glass. 4.3 The hiding power, H 0.98 of the coating is calculated from the reflectivity R ∞ and the scattering coefficient S. 4.4 As an optional procedure the contrast ratio C at a specified spreading rate H C is calculated from R ∞ and S. 5. Significance and Use 5.1 This is a precise instrumental method giving results having an absolute physical significance without reference to a comparison paint It should he used when maximum precision arid minimum subjectivity at required, as in terMing specitica. tion coatings or evaluating the hiding efficiency of pigznents
5-2 Hiding iwer Test Method 1)344 is visual instead ol insirumental. and gives results that are relative to a material standard instead cilabstilule. It is less precise than Test Method D2805 hut mote closely aligned with practical painting procedurn.
6. Apparatus and Materials
hI Sithnnstrs:
6.1.1 Black Gkn.s Panels, minimum size 200 by 2(X) mm. and appnisiniately 6-mm thick,
6.1.2 Black and White Paper Charrs—The surface shall be smooth and level, and impers ious to paint liquids. The black area shall lust a masimum reflectance of I % and the white area a nsinimuin reflectance of 78 %. The white area shall be non-fluorescent, as observed visually under ultra-violet illumination, or determined in accordance with Practice £1247.
62 Balance, accurate to 0.1 nsg.
6.3 Glgs.s Slides—Round or square plates of thickness similar to that used frir microscope specimen slides, with a minimum area of 40 cm2.
6-4 Rr$ectcsnrr-Mensuring Inorumen(’–One that allows only dilfusely rellected, radiant flux to be incident upon the measuring element. It shall employ a plsmimetric system, including source. lilters, and receptor, that poovides a response closely similar to the pniduct ut the spectral luminous clii. ciency function of the UIE standard observer and source C. It shall pruiside readings to at least the third decimal place and permit estimation to the fourth.
6.5 Tenqilase.5with a film area approximately 100 cm2 determined to the nearest tenth. Record the exact value on Line Cof the worksheet shown in Fig. I.
66 Donor Blade Film Applicators. width 150 mm. clearances 50. 75. 100. 125, 150. 175. and 200 sm.
6,7 Contpurer and Software, for sols-ing the relevant Kuheika-Munk equations
7. Pnwrdure
7.1 Generui lnseructian.s:
71,1 Film Applicarioit—Màke drawdowns manitally with a snsooth unifunin motion, -a the rare of about 6 cm/s. Hold paper chats flat by a sacuum plate a either suitable device while making drawdowns.
7.1.2 Reflectance Meayuwrr,nen,.—Mea,sure the reflectance of each test area at a minimum of three locations, reading or estimating 10 Itiur decimal places and calculating mean s’alues to the same. Place charts over a white surface and black glass over a black surface while measurements are being made.ASTM C954 pdf download.