Measure what you see. Pfund Cryptometer. Manual. A member of. Additives & Instruments

Transcription

1 Measure what you see. Pfund Cryptometer Manual A member of Additives & Instruments

2 BYK-Gardner Pfund Cryptometer Manual English PA-3301 BYK - Gardner USA 9104 Guilford Road Columbia, MD USA Phone Fax BYK-Gardner GmbH Lausitzer Str. 8 D Geretsried Germany Tel gardner ( ) Fax

3 Description Description Description DIRECTIONS FOR DETERMINING WET HIDING POWER BY THE USE OF THE PFUND CRYPTOMETER General Remarks: All parts of the instrument in particular the clear top plates must be kept perfectly clean. Caution: Do not use solvents to clean the base plate While sky-light may be used for illumination in some cases, artificial light a 100 watt or a 200 watt bulb has been found to yield the most reproducible results. Strong illumination should strike the Cryptometer from the scale side at an angle of 45. Allow as little light as possible to strike the eyes. For best results, conduct all tests at temperatures between 70 and 80 F. For a right-handed operator, the Cryptometer should always be assembled and operated so that the scale to be read is on the left, the pegs of the tilted top plate are on the right, and the light strikes the thin side of the wedge-shaped film from the left. A small amount of thin lubricant, applied to the outer surfaces of base plate only, where it is touched by the moving top plate, will prevent scratches that impair the accuracy of the instrument. Stir the paint sample thoroughly so that all pigments are uniformly distributed. Be careful to avoid air bubbles. Apply a small pool of paint to the center of the base plate. If too much paint is used, there will be an overflow into the longitudinal grooves and finally over the outer strips, which at all times must be kept free of paint. Select the top plate with the most appropriate wedge constant and place it with the pegs down on the side opposite the illuminated scale. The number (2, 3, 5 or 7) assigned to a top plate indicates the increasing slope of the underlying paint film. It also corresponds to the actual film thickness, in mils, when the touching edge is set to read 25.4 mm = 1 inch = 1,000 mils on the engraved scale. This check point should be marked very near the center of the 0-50 mm scale where the best precision can be obtained. It should be used to form a wet film of known thickness for selecting the proper top plate and moving it in the proper directions. To make a reading, press lightly but evenly on the four corners of the top plate, move it back and forth several times to force out all surplus paint, and then move it slowly to the left until the center line of demarcation has disappeared completely over its entire length because of increased wet film thickness. Record the scale reading, located directly under the lower left-hand corner of the top plate, and call it disappearance. After moving the top plate about 5 mm. further to the left, reverse the motion while still pressing down on the four corners as before. Move the top plate to the right slowly until the center line of demarcation reappears over its entire length because of decreased wet film thickness. Record the reading as before, and call it appearance. The average of 5 such pairs of readings will provide a practical mean for the Cryptometer setting corresponding to visual hiding. Rest the eyes by looking at a dull black surface (such as black felt) or by closing them for a minute, and 2 3

4 Description Description DIRECTIONS FOR SELECTING TOP PLATES then confirm visual hiding of the paint sample at the average setting. The number of square feet of surface area visually hidden by one gallon of paint is quickly determined by reference to Table 1 on Page 2. The corresponding thickness of wet paint in mils (1 mil = inch) can also be determined from Table 1. For Example: If a No. 7 top plate with a wedge constant of results in an average Cryptometer setting of 27mm, then the wet paint will hide visually at the rate of 215 square feet per gallon, and the wet film thickness will be 7.44 mils. This target film thickness can be controlled by checking it periodically with the Pfund Film Gauge to assure uniform wet hiding. A top plate is identified by a number from 1-9 that is equal to the thickness, in mils, formed by the wedge over the central line when the Cryptometer is set at inch = 1,000 mils = 25.4 millimeters. The wedge constant is therefore numerically equal to the slope of the top plate caused by the length of its protruding pegs. These pegs can become worn down by prolonged use over abrasive pigments, or otherwise damaged. When ordering extra top plates, be sure to specify the correct wedge constant that is desired, and also the model of Cryptometer with which it is to be used. The three standard top plates are now identified as follows: No. 2 with Wedge Constant K = No. 3.5 with Wedge Constant K = No. 7 with Wedge Constant K = Other top plates with other wedge constants are available on special order DIRECTIONS FOR BLACK-AND-WHITE CRYPTOMETER This all-purpose model is applicable not only to black and white paints, but to paints of all colors. It is furnished with Top Plate No. 2 for darker paints and Top Plate No. 7 for lighter paints. In case of doubt, it is advisable to use the top plate which results in a setting nearest to 25.4 mm. on one of the scales. In using the Black-and-White model with Top Plate No.2 for black or near-black paints, it is important to use an intense, constant and reproducible artificial source of illumination. A 200-watt lamp is recommended. To obtain reproducible readings for colored paints the following steps should be taken in order: (1) Follow carefully the instructions given under General Remarks on Page 1 (2) Place the Cryptometer so that the black field is to the left, apply a small pool of paint at the dividing line between the black and white fields, lay the top plate on it so that the pegs are to the right, an make 5 pairs of readings for disappearance and appearance. (3) Reverse the Cryptometer so that the white field is to the left, and proceed as before to make 5 pairs of readings (4) Average the 5 quadruple sets of readings disappearance and appearance over both black and white fields to obtain a practical mean setting that can be confirmed for visual hiding after resting the eyes (5) Refer to Table 1, under the column heading for the top plate used, to obtain the corresponding Wet Hiding Power in square feet per gallon or square meter per liter and also the corresponding Wet Film Thickness in mils or thousandths of an inch or microns. 4 5

5 Operation Operation 6 TABLE 1. WET HIDING POWER AND WET FILM THICKNESS Cryptometer Setting Hiding Power No. 2 Top Plate K = Thickness (mm) ( M²/L) ( ft.²/gal.) (microns) (mils) 1 510, ,0066 0, , ,0132 0, , ,9944 0, , ,001 0, , ,0076 0, , ,9888 0, , ,0208 0, , ,002 0, , ,9832 0, , ,0152 0, , ,0218 0, , ,0284 0, , ,0096 1, , ,0416 1, , ,0228 1, , ,004 1, , ,036 1, , ,0426 1, , ,0492 1, , ,0304 1, , ,0624 1, , ,0182 1, , ,0502 1, , ,006 1, , ,038 1, , ,07 2, , ,102 2, , ,0832 2, , ,039 2, , ,071 2, , ,0268 2, , ,0588 2, , ,04 2, , ,072 2, , ,104 2, , ,136 2, , ,1172 2, , ,073 2, , ,105 3, , ,0862 3, , ,1182 3, , ,074 3, , ,106 3, , ,0872 3, , ,1192 3, , ,075 3, , ,0562 3, , ,0628 3, , ,0948 3, , ,076 3,94 7

6 Operation Operation 8 TABLE 1. WET HIDING POWER AND WET FILM THICKNESS Cryptometer Setting Hiding Power No. 3.5 Top Plate K = Thickness (mm) ( M²/L) ( ft.²/gal.) (microns) (mils) 1 284, ,5052 0, , ,0358 0, , ,4902 0, , ,0208 0, , ,5006 0, , ,0058 0, , ,511 0, , ,0162 1, , ,496 1, , ,0266 1, , ,5064 1, , ,037 1, , ,5168 1, , ,022 1, , ,5272 2, , ,007 2, , ,9788 2, , ,992 2, , ,548 2, , ,0278 2, , ,4568 2, , ,9874 3, , ,518 3, , ,074 3, , ,503 3, , ,059 3, , ,488 3, , ,044 3, , , , ,902 4, , ,458 4, , ,014 4, , ,57 4, , ,999 4, , ,428 4, , ,444 4, , ,54 5,1 38 7, ,096 5, , ,398 5, , ,954 5, , ,51 5, , ,812 5, , ,955 5, , ,178 6, , ,48 6,2 46 6, ,036 6, , ,592 6, , ,148 6, , ,704 6, , ,006 6,89 9

7 Operation Operation TABLE 1. WET HIDING POWER AND WET FILM THICKNESS Cryptometer Setting 10 Hiding Power No. 7 Top Plate K = Thickness (mm) ( M²/L) ( ft.²/gal.) (microns) (mils) 1 142, ,0104 0, , ,0208 0, , ,0058 0, , ,0162 1, , ,0266 1, , ,037 1, , ,022 1, , ,007 2, , ,992 2, , ,0532 2, , ,835 3, , ,82 3, , ,932 3, , ,044 3, , ,902 4, , ,887 4, , ,872 4, , ,984 4, , ,096 5, , ,208 5, , ,939 5, , ,924 6, , ,036 6, , ,148 6, , ,006 6, , ,118 7, , ,976 7, , ,088 7, , , , ,058 8, , ,17 8, , ,155 8, , ,14 9,1 34 4, ,855 9, , ,11 9, , ,095 9, , ,08 10,2 38 3, ,192 10, , ,05 10, , ,162 11, , ,274 11, , ,132 11, , ,244 11, , ,102 12, , ,214 12, , ,072 12, , ,93 12, , ,042 13, , ,9 13,5 50 2, ,012 13,78 11

8 Operation The formulas used to construct the above Table 1 may be simplified as follows H. P. = 40.7/K x L and T = K x L x 39.4 WHERE H. P = Wet Hiding Power (in square feet per gallon) K = Top Plate Wedge Constant (slope) L = Cryptometer Setting (in millimeters) T = Wet Film Thickness (in mils or thousandths of an inch) 12

9 EDFIS 0408 Europe