Calibration Adjustment; Calibration Method - Elcometer 456 Operating Instructions Manual

5 CALIBRATION ADJUSTMENT

Calibration adjustment is the process of setting the
gauge to known values of thickness to ensure accuracy
on different substrate types, shapes and surface
finishes.
Note: When using an FNF probe it must be calibrated in
both the ferrous mode and in the non-ferrous mode to
ensure accuracy of reading.

5.1 Calibration method

The calibration of the gauge can be adjusted
(MENU/CAL METHOD) using several different methods
described in National and International Standards.
The calibration adjustment method chosen is dependant
on the condition of the substrate to be measured and is
indicated on the screen by a symbol (Figure 18):
Figure 18. CAL METHOD screen
SMOOTH. Smooth surface calibration where the gauge
is set to zero on the uncoated surface and a known
thickness above the expected thickness of the coating.
2POINT. Calibration on a thin value and a thick value
either side of the expected thickness. This enhances the
accuracy of the gauge over the thickness range defined
by the two values.
ROUGH. A calibration method similar to 2-Point. This
enhances the accuracy of the gauge over the thickness
range defined by the two values.
SPECIAL SUB. This method uses the 2-Point
calibration for unusual substrate materials such as cast
iron, certain types of stainless steel, high carbon steel,
special aluminium alloys, etc.
ZERO OFFSET. This is the method described in
ISO 19840 for coatings on steel surfaces roughened by
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