A glass surface that needs only routine cleaning with soap and water and shows no remaining bonded residue or visible damage after it is clean and dry.
GlassRenu · Educational illustration
Meaning and boundaries
Category 0 is not restoration damage. If a condition remains after routine cleaning or requires a solvent, specialty cleaning agent, abrasion, or polishing, it belongs in Category 1 through Category 5.
Why it matters in glass restoration
This category prevents ordinary soil from being diagnosed as damage and avoids unnecessary chemical treatment, abrasion, polishing, or replacement.