Novasys Group presents the Grindometer acc. to Hegman, Model 232, developed specifically to establish the fineness of grind of coating materials.
Grindometer testing instruments are used to produce a liquid wedge-shaped specimen of the test substance, which can be easily examined visually where the grain size is larger than the local dimensions of the wedge channel. A reading of the appropriate channel depth is taken at the boundary between the uneven and smooth surface areas of the sample to determine the fineness of grind.
The Grindometer acc. to Hegman, Model 232 consists of a block of hardened steel specially treated to ensure dimensional stability. Two precisely defined, wedge-shaped channels are cut into the block with the depth of each channel measured on a μm scale engraved into one of the longitudinal sides (length 125mm) of the block. The corresponding Hegman scale (HS) is shown on the opposite side.
In addition to the standard version with scale combination Hegman/μm, versions with other scale combinations (a maximum of two, alternatively from Hegman/μm/North/mils/FSPT) are available on request.
Grindometers are suitable for measuring ranges 15/ 25/ 50 and 100 μm. A straightedge scraper for applying the test material is also included with the instrument.
A sufficient quantity of the test material is poured into the deep end of the channels of the Grindometer, and spread in an even motion to the shallow end of the channels, holding the straightedge scraper vertical to the surface of the test instrument and also vertical to the channels.
The evaluation should be conducted within three seconds of application, which can be done by viewing the surface of the specimen at right angles to the channels by counter light coming at a flat angle (20º - 30º). A reading is taken of the point at which aggregated particles or scratch marks become visible. The corresponding channel depth at this point is then defined as the fineness of grind.
The Grindometer test instrument should be cleaned immediately after use only with a solvent. Scraping of paint residue using hard, sharp implements should be avoided. The straightedge should always be applied with a minimum of pressure and checked at regular intervals as the blades are subject to constant wear.