A rubbed or abraded area of a glass coating that changes gloss, color, reflectance, transmittance, or continuity without necessarily forming one narrow scratch.
GlassRenu · Educational illustration
Meaning and boundaries
Coating rub is distinct from metallic rub transferred onto glass and from residue that merely sits on the coating.
Why it matters in glass restoration
The affected coating generally cannot be recreated by polishing the glass, and attempted cleaning may enlarge the damage.