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 A
10x Measuring Magnifier is included with each Taber®
Shear / Scratch Tester. This allows you to visually measure the
width of a scratch to the nearest thousandth of an inch. For more
precise measurements, TABER recommends an OPTICAL MICROMETER.
For
comparable and reproducible results, it is recommended that tests
be tightly controlled. Some of the influences that may affect the
shear resistance of organic materials include: temperature, humidity,
age of specimen material, etc.
Diamond
Scratch Test
The standard criterion for scratch resistance is the minimum load
required to penetrate the surface of the testing material with
the diamond tool. A standard scratch width should be established
for each type of material and used for comparison to determine
test end point. Test results can be compared using the load required
to duplicate the scratch.
Shear
Tests
The standard criterion for shear resistance is the minimum load
necessary to shear the surface of the testing material with the
shear tool. For best results, you should perform multiple shear
tests of approximately ½" length. From these, select
the most uniform grooves and average the width measurements.
NOTE:
An irregular or 'jumpy' cut not caused by careless test procedures,
may indicate lack of uniform composition or surface irregularities.
Adhesion
of Coatings
Using the TABER Shear / Scratch tester, adhesion of coatings can
be rated. This is determined by recording when the tool breaks
through the junction of the topcoat and the undercoat. Suggested
ratings include:
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