How can you determine if a coating is installed on a window?

The most effective method to determine whether a coating is applied to a window is by using a lighter or match to count reflections. This technique takes advantage of the characteristic behavior of coated glass surfaces when light reflects off them.

When you shine a light source, such as a lighter or match, onto the glass, the reflections will vary based on the presence of coatings. Coated windows typically have multiple reflections due to the thin film of material applied, which alters the way light interacts with the glass. If you see an unusual number of reflections, it indicates the presence of a low-emissivity (Low-E) coating, which is often transparent and difficult to detect visually without this method. The specific nature of the coating affects the number and quality of reflections, making this approach a reliable means of identification.

Inspecting for discoloration may indicate some surface treatment but is not a definitive method for determining specific coatings. Checking the thickness of the glass won't necessarily provide any information about coatings, as various types of glass can have similar thicknesses regardless of whether they are coated or not. Measuring the temperature of the glass could provide some clues about energy performance but does not directly indicate the presence of a coating. Therefore, counting reflections with a light source is the most precise