Loss of one or more required edge-seal functions in an insulating glass unit, potentially allowing excessive moisture or gas exchange, fogging, contamination, displacement, or loss of durability.
GlassRenu · Educational illustration
Meaning and boundaries
A cloudy appearance alone does not prove edge-seal failure because deposits, coatings, films, etching, or condensation may occur on different surfaces.
Why it matters in glass restoration
Correct diagnosis prevents polishing an accessible surface when the actual condition is inside a sealed cavity or at the perimeter assembly.