Mineral salts and other substances present in water at the molecular or ionic level rather than as visible suspended particles.
GlassRenu · Educational illustration
Meaning and boundaries
Dissolved solids are not the same as water hardness. Hardness mainly reflects calcium and magnesium, while dissolved solids can include many other ions and compounds.
Why it matters in glass restoration
As water evaporates, dissolved constituents can concentrate and contribute to visible residue or chemically active deposits on glass.