A persistent film, veil, or discoloration associated with mineral-bearing water that remains after a controlled reveal while the truly clean glass substrate remains non-relief (SC-0).
GlassRenu media library · Image source · Image source
Meaning and boundaries
Hard-water staining is a non-etch condition in this glossary and DSS system. If modeled micro-texture remains on a clean substrate, use Mineral Etching (DSS Ch.03.03); if material fully clears, use Mineral Deposits (DSS Ch.03.01).
Why it matters in glass restoration
A controlled definition can prevent users from treating every cloudy water mark as the same problem or assuming one restoration method will apply.