Measure what you see.
Hoffman Scratch Hardness Tester Manual Cat. No.: 1610 BYK - Gardner USA 9104 Guilford Road Columbia, MD 21046 USA Phone 800-343-7721 301-483-6500 Fax 800-394-8215 301-483-6555 www.byk.com/instruments BYK-Gardner GmbH Lausitzer Str. 8 D-82538 Geretsried Germany Tel.
Description Description This instrument consists of an applicator blade The Hoffman Scratch Hardness Tester was developed by the National Paint, Varnish and Lacquer Association and has been produced by BYK-Gardner for many years. This instrument was designed to fill the need for a simple portable device to rate scratch resistance and adhesion of industrial product finishes on a comparative basis. It is an ideal tool for laboratory or field use.
General Information General Information The Hoffman Scratch Tester consists of a fourwheeled carriage, a balanced beam with a scale of 0-20 arbitrary units and a scratching tool with a sharp circular rim mounted at 450 to the test surface. a counterweight, allen wrench and movable weights (riders) both large (100 g) and small (25 g) are also included. The overall dimensions of this instrument are 11 x 1 x 1 inches ( 27.9 x 2.5 x 2.5 cm).
Calibration Procedure Calibration Procedure Place the Hoffman Scratch Tester on a flat, level surface with the wheels of the roller carriage contacting the surface and the scale arm positioned to the left. The scale arm has no riders attached. 1. Using the small allen wrench, loosen the counter weight until it slides across the scale arm. 2. The correct position for the counter weight is when the scratching tool is in contact with the surface with virtually no downward force.
Calibration Procedure • At this point, a small upward tap on the scale arm should cause it to settle in a higher position; the scratching tool is not in contact with the surface (position 2). The optimal calibration is reached when the smallest amount of force is required to raise the scale arm from position 1 to position 2. If the scale arm will not stay in position 1 on its own and goes directly to position 2, the counter weight needs to be shifted to the left.
Operation Operation Before initial setup, please remove protective film from the scale arm (balanced beam). In operation, small and/or large riders are attached to this arm at the numbered positions. These must be placed on the scale very carefully so that the test surface is not marred before actual testing is begun. The large rider generates a load of 100 grams per division, while the small rider generates a load of 25 grams per division.
Operation hand on the carriage platform directly over the pair of wheels nearest to the scratching tool, using sufficient downward pressure to lift the counterpoised beam with the selected rider at the 0 position. Pull the carriage in the opposite direction from the scratching tool in order to cause a trailing scratch.
Maintenance and Care Maintenance and Care The scratching tool should be rotated between series of tests to equalize wear; and replaced when the edge becomes dulled. It is made of special tool steel and should give long service on conventional finishes if used properly. Always approach the final reading from the lower end of the scale to prevent overloading and dulling the cutting edge against very hard substrates. Do not lubricate the Hoffman Scratch Tester.
253 017 659 EDFIS 0408 Europe
