3 Micrometers- Suitable micrometers for measuring the
width and thickness of the test specimen to an incremental
discrimiation of at least 0.025 mm (0.001 in.) should be used.
All width and thckness measurements of rigid and semirigid
plastics may be measured with a hand micrometer with ratchet.
A suitable instrment for measurng the thickness of nonrgid
test specimens shall have: a contact measurng pressure of
25 :t 2.5 kPa (3. 6 :t 0.36 psi), a movable circular contact foot
6.35 :t 0.025 mm (0.250 :t 0.001 in.) in diameter and a lower
fixed anvil large enough to extend beyond the contact foot in
al diections and being parallel to the contact foot within 0.005
mm (0.002 in.) over the entie foot area. Flatness of foot and
anvil shall conform to the portion of the Calibration section of
Test Methods D 5947.