1、 FORD LABORATORY TEST METHOD BI 161-01 Date Action Revisions 2001 03 20 Revised Editorial no technical change A. Cockman 1996 10 02 Printed copies are uncontrolled Page 1 of 3 Copyright 2001, Ford Global Technologies, Inc. MAR RESISTANCE DETERMINATION FOR AUTOMOTIVE COATINGS Application This procedu
2、re is used to determine the mar resistance of automotive coatings. Equipment Required Manual or Mechanically Driven Mar Tester The Mar Tester has a cylindrical acrylic, brass, or wooden finger, 16 mm in diameter, which has a flat, smooth end and slightly rounded edges to prevent abrading. The cylind
3、rical finger shall exert a force of 9 N on the test surface and have a stroke of approximately 100 mm. The Mar Tester may be either manually or mechanically driven. Source: Atlas Electric Devices Co. Wentworth Instruments Ltd. 4114 N. Ravenswood Avenue North Green, Dachet Chicago, IL 60613 U.S.A. Sl
4、ough, SL3 9JH England Firma Walter Thoma 7888 Rheinfelden/Baden Wehrstrabe 6, Germany Polishing Paper 281Q 3M “WETORDRY PRODUCTION POLISHING PAPER“ (2-micron grade) Source: Microfinishing Systems Industrial Abrasives Division/3M 251-2A 3M Center St. Paul, MN 55144 Felt Cloth 14-9956-000 Felt, Green,
5、 50 mm x 50 mm Source: Atlas Electric Devices Co. 4114 N. Ravenswood Avenue Chicago, IL 60613 FORD LABORATORY TEST METHOD BI 161-01 Page 2 of 3 Copyright 2001, Ford Global Technologies, Inc. Glossmeter Micro-Gloss 20 degree Glossmeter, Model GB4532 (or equivalent) Source: Byk Gardiner 2435 Linden La
6、ne Silver Spring, MD 20910 U.S.A. Conditioning 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 otherwis
7、e specified. Panel Preparation Panels are prepared according to the requirements of the topcoat material specification being tested unless otherwise directed. For uniformity, black is the preferred color for test purposes, but if a different color is used, any comparisons should be made using that c
8、olor. Procedure Part A . Cut a 50 mm x 50 mm square of 3M Polishing Paper and place it over a similar size square of felt with the abrasive side of the polishing paper facing outward. . Mount the two squares over the finger of the mar tester, keeping the felt between the finger and the polishing pap
9、er. . Use a ring clamp to secure the two squares on the finger. Part B . Measure the 20 degree gloss of the coated surface to be tested. . Subject the test surface to ten (10) double strokes (or as required by the material specification) of the mar tester. The test surface must be secured and can no
10、t move during test. If a manually driven mar tester is used, the speed shall approximate that of a mechanically driven mar tester (10 double strokes per 15 seconds). . Measure the 20 degree gloss of the abraded area in a direction parallel to the rubbing stroke of the mar tester, and record the lowe
11、st reading. FORD LABORATORY TEST METHOD BI 161-01 Page 3 of 3 Copyright 2001, Ford Global Technologies, Inc. . Mar resistance is expressed as percent gloss retention as follows: % gloss retention = 20 degree gloss of abraded area x 100 Original 20 degree gloss The reported mar resistance shall be th
12、e average of three (3) determinations on one sample. NOTE: A new square of polishing cloth is required for each determination of mar resistance. Chemicals, materials, parts, and equipment referenced in this document must be used and handled properly. Each party is responsible for determining proper
13、use and handling in its facilities. MAR RESISTANCE DETERMINATION FOR AUTOMOTIVE COATINGS REPORT SHEET Description of Coating:_ Specification:_ Bake Schedule:_ Film Thickness (mils):_ Color:_ Initial 20 degree gloss:_ Abraded 20 degree gloss: _ First determination Abraded 20 degree gloss: _ Second determination Abraded 20 degree gloss: _ Third determination Average abraded gloss: _ (add first, second, and third runs and divide by 3) Calculate percent gloss retention as follows: % Gloss Retention = Average 20 degree abraded gloss x 100 Initial 20 degree gloss
