Glass carrying an intentionally deposited surface layer that changes optical, thermal, reflective, decorative, or other performance.
GlassRenu · Educational illustration
Meaning and boundaries
A deposited coating is not the same as a through-body tint, removable film, residue, or corrosion layer.
Why it matters in glass restoration
An exposed coating may be damaged or removed by abrasives, chemicals, razors, or polishing even when the base glass would tolerate the process.