That's what we are working to substantiate. Keep tuned for more statistical data if that's your kind of thing. 

What we do know is ceramic enamel (frit) weakens heat-strengthened and tempered glass. It has been demonstrated and proven by many sources, including the frit manufactures themselves. We also know that the heat gain in a spandrel cavity can get quite high. Couple the two together and thermal breakage occurs, and is happening more and more. 

Want a product that doesn't weaken your glass product, adds fallout protection if it does? Maybe you want more color for your project and a much greener product for your project. Check out OPACI-COAT-300. 

I'll leave you with this great video shot a few days ago. 13 mil applied OPACI-COAT-300, a 1.18# steel ball dropped from 11.5 feet high. This is an actual ASTM test standard for breakage of glass. Clear tempered glass breaks around a 4 feet high ball dropped.