1、 FORD LABORATORY TEST METHOD BI 101-01 Date Action Revisions 2001 03 13 Revised Editorial no technical change A. Cockman 1990 05 11 Printed copies are uncontrolled Page 1 of 5 Copyright 2001, Ford Global Technologies, Inc. MEASUREMENT OF HIDING POWER OF PAINT - CRYPTOMETER METHOD Application This me
2、thod is used to measure the hiding power of paints of all colors by means of a Cryptometer. The hiding power of paint is that property which enables the paint to completely obliterate any background upon which it may be applied. Apparatus Required Black and White Cryptometer The Cryptometer (Figure
3、1) consists of two glass plates. The lower plate is opaque glass with a white field and a black field, each having a millimeter engraved scale. The top plate is a transparent piece of glass with two small metal pegs under one end which give a constant angle between the upper and lower plates. A samp
4、le of paint placed between the two glass surfaces forms a paint wedge of varying thickness. To determine the hiding power of the paint, the paint wedge is moved across the bottom plate until it completely hides the lines of demarcation formed by the black and white fields of the lower plate. A readi
5、ng on the millimeter scale taken at this point indicates the hiding power of the paint. Source (or approved alternative supplier): Koehler Instrument Co. Sheen Instruments Ltd. 1595 Sycamore Avenue Richmond, Surrey Bohemia, NY 11716 U.S.A. England Tel: (516) 589-3800 Erichsen GmbH K.G. 587 Hemer - S
6、undwig West Germany Illuminated Viewing Box A box (Figure 2) which excludes stray light and allows illumination from a 100 watt bulb to strike the instrument at an angle of 45 is recommended for obtaining accurate readings. Preparation of Sample Paint samples should be thinned to the viscosity requi
7、red by the relevant material specification with the solvent specified before measuring hiding power by the Cryptometer method. Viscosity shall be determined in accordance with FLTM BI 111-01. FORD LABORATORY TEST METHOD BI 101-01 Page 2 of 5 Copyright 2001, Ford Global Technologies, Inc. Conditionin
8、g and Test Conditions All test values indicated herein are based on material conditioned in a controlled atmosphere of 23 +/- 2 C and 50 +/- 5 % relative humidity for not less than 24 h prior to testing and tested under the same conditions unless otherwise specified. Procedure 1. Place the instrumen
9、t in the illuminated viewing box so that the black field is to the right. 2. Apply a small sample of the thoroughly mixed paint (approximately 2 mL) at the dividing line between the black field and the white field. 3. Select the top plate with the proper wedge constant (see note) and lay it on top o
10、f the paint sample so that the pegs are to the left. Note: Two top plates are furnished with the Cryptometer. A No. 2 with a wedge constant of 0.051 mm is used for darker paints. For lighter paints use a No. 7 top plate with a wedge constant of 0.001 mm. If in doubt, select a top plate which results
11、 in a reading nearest to the 15 mm or 20 mm markings on one of the scale. 4. Press down on the four corners of the top plate with very light even pressure. Move the top plate back and forth to force out surplus paint (excess paint should flow on to two longitudinal grooves, but not on the outer stri
12、ps). Now slide the top plate slowly to the right until the line of demarcation on the base plate, formed by the black and white fields, has disappeared completely over its entire length. Immediately record the reading appearing on the engraved scale directly under the lower right hand edge of the to
13、p plate. Repeat the operation until three readings are in agreement within +/- 1 mm. If it is not possible to obtain three readings which agree within +/- 1 mm, a fresh sample must be poured and the procedure repeated. 5. Turn the Cryptometer about so the white field is on the right, but keep the to
14、p plate with the pegs to the left and repeat the readings until three agree within +/- 1 mm. If it is not possible to obtain three readings which agree within +/- 1 mm a fresh sample must be poured and the procedure repeated. 6. Report the Cryptometer reading as the average of all six readings taken
15、. Note: 1. Since the evaporation of thinners affects the hiding power of paint, all six readings should be completed within 120 s of pour-out. 2. Frequent examination must be made for worn pegs and wedges which must be replaced when proper wedge constant is not made. FORD LABORATORY TEST METHOD BI 1
16、01-01 Page 3 of 5 Copyright 2001, Ford Global Technologies, Inc. The constant of the No. 7 wedge may be checked by means of a 2.5 mm feeler gage. Place the feeler gage with the edge at 0.0 mm on the length scale. Move the wedge back until it will not slide further and read the scale. The reading sho
17、uld be 36.3 mm. If the reading is more than 0.5 mm off, determine the correction factor, i.e., for a reading of 35.3 mm the factor would be x 1.03. This multiplier may then be applied to readings where the specification is in simple Cryptometer units. The No. 2 wedge is difficult to check by this me
18、thod and should be returned to the factory if it appears to be worn. Chemicals, materials, parts, and equipment referenced in this document must be used and handled properly. Each party is responsible for determining proper use and handling in its facilities. FORD LABORATORY TEST METHOD BI 101-01 Pa
19、ge 4 of 5 Copyright 2001, Ford Global Technologies, Inc. MEASUREMENT OF HIDING POWER OF PAINT - CRYPTOMETER METHOD Figure 1 BLACK AND WHITE CRYPTOMETER A - Metal Base B - Opaque Black Glass (1/2 bottom plate) C - Opaque White Glass (1/2 bottom plate) D - Transparent Glass Top Plate E & F - Groove in
20、 Bottom Plate to Allow for Overflow of Paint G & H - Groove in Top Plate to Allow for Overflow of Paint I & J - Metal Pegs Ground to Produce Proper Angle Between Plates K - Mm Scale L & M - Sharp Line of Demarcation between Hidden Surface and Surface which is not Hidden X - Distance in mm to be read
21、 on Scale K at Appearance and Disappearance of Sharp Line L-M FORD LABORATORY TEST METHOD BI 101-01 Page 5 of 5 Copyright 2001, Ford Global Technologies, Inc. MEASUREMENT OF HIDING POWER OF PAINT - CRYPTOMETER METHOD Figure 2 ILLUMINATED VIEWING BOX FOR CRYPTOMETER A - 100 Watt Bulb Centered in Opening and 219 mm from Center of Bulb to Surface of Box Base. B - Chrome Plated or Aluminized Steel Reflector.
