Hegman_gauge
A Hegman gauge, sometimes referred to as a grind gauge, grind gage, or grindometer, is an instrument which indicates the fineness of grind or the presence of coarse particles and agglomeration in a dispersion.[1] It is commonly used to determine how finely ground the particles of pigment (or other solid) dispersed in a sample of paint (or other liquid) are. This is important because many types of solid materials must be ground into finer particles in order to be dispersed in liquids.[2] The resulting properties of the dispersion vary based on the size of individual particles and the degree which they are dispersed.
The Hegman gauge usually consists of a stainless steel block with a series of very small parallel grooves machined into it. The grooves decrease in depth from one end of the block to the other, according to a scale stamped next to them. A typical Hegman gauge is 170mm by 65mm by 15mm, with a channel of grooves running lengthwise, 12.5mm across and narrowing uniformly in depth from 100 μm to zero and used to determine particle size.[3]