Your windows have an insulated glass unit (IG) that consists of two panes of glass with a metal spacer in between them that are adhesively sealed to the spacer. On the inner surface of the glass, a LoE coating is applied. A LoE coating is a microscopic, metallic oxide that is nearly invisible coating that help to improve the energy efficiency of windows by blocking part of the sun’s heat in summer and reduces heat from escaping in winter.
If the LoE coating fails, you will start to see small spots appear in between the 2 panes of glass. Because this condition is in between the panes of glass, you are not able to wipe them away. Over time, the spots will grow as more of the microscopic, metallic oxide fails; the small spots will become larger areas over time.
