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6 MEASURING INDENTATION HARDNESS (BUCHHOLZ)
This test is carried out with the Indenting Tool (tool No. 6) in conjunction with the slip-on weight, and in
accordance with DIN 53 153. The indenting tool incorporates a disc which has a sharp bevelled edge.
Pressure between the disc and the coating results in an indentation being formed in the coating.
Measurement of the dimensions of the indentation reveals the indentation hardness of the coating.
1. Turn the rotary head to position 6.
2. Place the slip-on weight onto the PIG.
3. Place the PIG onto the surface to be tested with the indentation tool in contact with the test area.
4. Leave the PIG for 30 seconds (timed using a stopwatch) and then lift the PIG carefully away from the
surface.
5. Remove the weight.
6. Position the PIG so that the microscope lens is over the indentation with the feet touching the surface.
7. Press and hold the light switch to illuminate the indentation.
8. Focus the microscope until the indentation is clearly visible.
9. Align the graticule scale at right-angles to the indentation so that the scale divisions are parallel to the
indentation.
10. Measure and record the length of the indentation in the coating by counting the number of graticule
divisions.
The length of the indentation is inversely proportional to the hardness of the coating; use Table 2 to
determine the indentation resistance and depth