The measured particle-size distribution of an abrasive and the named grading system used to designate it.
GlassRenu · Educational illustration
Meaning and boundaries
A grit number is not a universal particle diameter; P, F, ANSI, JIS, micron, and proprietary grades use different definitions and distributions.
Why it matters in glass restoration
Correct designation prevents false comparisons among discs, powders, and compounds and supports controlled stage progression.