DeFelsko PosiTector 6000 Instruction Manual page 14

Verification
Verification is an accuracy check performed by the user using
known reference standards. A successful verification requires the
Gage to read within the combined accuracy of the probe and the
reference standards.
A reference standard is a sample of known thickness(es) against
which a user may verify probe accuracy. Reference standards may
be plastic shims, coated thickness standards, or sample parts
whose coating thickness has been determined using other means.
Verify accuracy at the beginning and the end of each work shift.
During the work shift, if the Gage is dropped or suspected of giving
erroneous readings, its accuracy should be re-verified. In the event
of physical damage, wear, high usage, or after an established
calibration interval; the probe should be returned to the
manufacturer for repair or calibration.
Adjustment
Adjustment, or Calibration Adjustment (pg 23), is the physical act
of aligning the probe's thickness readings to match those of a
known thickness sample (removal of bias) in order to improve the
accuracy of the probe on a specific surface or in a specific portion
of its measurement range. Zero (pg 24), 1-point (pg 25) or 2-point
(pg 26) Calibration adjustments are possible.
Probes are factory calibrated and perform an automatic self-check
each time a measurement is taken. The XX symbol is displayed
when factory calibration setting is in use.
For many applications no further adjustment is necessary.
Just check Zero on the uncoated substrate, then measure.
However, sometimes probe readings can be influenced by
changes in substrate shape, composition, and surface roughness
or by measuring in a different location on the part. That is why Cal
adjustments are made possible.
Where a Cal adjustment method has not been specified, use a
Zero or 1-point method first. If measuring the included shims on
your uncoated surface reveals inaccuracies, use the 2-point
method.
11