Spandrel glass is typically used in non-vision areas used to hide construction materials, heating ducts, columns, or create the look of an additional floor. Spandrel is a paint applied to clear glass that passes through a tempering oven to “bake” the paint into a hard, ceramic coating. During that process, pin holes may appear.
Spandrel coating can be on surfaces 2, 3,or 4. Surface #2 is the most common and paired with a clear glass. LoE coatings increase heat buildup inside the glass due to the dark colors so argon should not be used in those makeups.