BUCHHOLZ Hardness
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BUCHHOLZ hardness
Indentation resistance according to BUCHHOLZ
The Buchholz hardness test is used to assess the hardness of polymer coating materials (paints) in accordance with ISO 2815. In this standard, BUCHHOLZ hardness is referred to as “Buchholz indentation resistance” (Eindruckwiderstand nach Buchholz).
| Fig. 1: | Schematic illustration of BUCHHOLZ identation test |
Experimental conditions
The indenter here is a small metal wheel (wheel-shaped cutting edge) with sharp edges in hardened tool steel, as shown in Fig. 1. The test load is 4.905 N for a duration of 30 s. The length l of the lens-shaped indentation is evaluated, whereby the dimensionless hardness value is calculated as 100 mm/l. The method is suitable for coating thicknesses in the range of 15 to 35 µm. The penetration depth must be between 5 and 24 µm.
Testing equipment
Figure 2 shows commercially available testing devices for determining the BUCHHOLZ hardness.
| Fig. 2: | BUCHHOLZ hardness tester (a): Type 263 from Erichsen GmbH & Co.KG, Hemer, and (b) from Qualitest Inc., Buffalo, USA |
See also
- Hardness
- Conventional hardness testing
- Scratch hardness
- Instrumented scratch testing
- Scratch resistance
References
- ISO 2815 (2003-04): Paints and Varnishes – Buchholz Indentation Test
- Brock, T., Groteklaes, M., Mischke, P., Strehmel, B.: Lehrbuch der Lacktechnologie. Vincentz Network, 5th Edition, Hannover (2017), ISBN 978-3-86630-619-6