Here at Invisirail, our glass undergoes several stages before we consider it ready to be used in our railing system. This post talks about a very important step called heat soaking.

When glass is made, manufacturers try to ensure the glass is as pure as possible. However, sometimes a few contaminants go undetected, even after the glass is tempered (a heating process designed to strengthen it). Nickel-based specks from raw glass or rollers lead to impurities that are so small, they can’t be seen by the human eye. These tiny particles are called Nickel-Sulfide Inclusions. We want to find panels with these imperfections, because they have a higher risk of shattering in the field (usually during or after installation) when weather conditions heat or cool the glass.

To find these pieces, we place our glass in a 265˚C oven for 6 hours. This soaking of the glass at high heat causes the inclusions to change shape, shattering the panel. When we are done, any panel still intact is ready for use in our railing system. Our heat soaking machine can handle 2800 kg (for reference, that’s 72 of our 10mm D panels, or almost 375 linear feet of glass!). This lets us treat each and every panel, and the process is 99.99% effective at removing inclusions. This means our glass is some of the purest available. 

Not all railing merchants use heat soaking to improve their product. Ontario building code only requires it when the system has no top rail. But even so, there is no North American standard for heat soaking. To maintain quality, we use a European standard, requiring specialists from Spain to personally certify our oven on site. This extra step guarantees that all our customers receive the safest possible product. The combination of tempering and heat-soaking is also used in the creation of glass for other demanding applications, like passenger vehicle windows, cellphone screens, and bulletproof glass. We also use it on our shower door glass, even though it is not required. These extra measures make sure our customers get both safety and style.