The Impressor is a precision mechanical instrument and should always be handled with care. The deflection indicator built-in to the Impressor has a normal reading of zero when not in use.
The Indenter Point has a tip precisely-machined to very small dimensions. It should be used with care to prevent damage. Avoid sliding or scraping the Indenter Point when it is in contact with the surface being tested. If the Indenter Point is damaged, it must be replaced with a new one. The Impressor ships with two spare Indenter Points.
Do not attempt to regrind an Indenter Point when damaged! The mechanical dimensions of the Indenter Point determine the accuracy of readings and will create erroneous reading when reground.
To check the condition of the indenter point, first visually inspect it for damage. Then place the impressor on a hard, flat surface with the appropriate test disk positioned under the indenter point. Press the impressor handle down firmly, but carefully, to avoid sideways slippage of the indenter point. The reading on the indicator should be within the range of values stamped on the test disk. If it is not, refer to the calibration procedure below.