The greatest challenge of working with dichroic-coated glass is preventing the coating from burning. Both beginners and professionals worry about how much heat is going into the glass, what their atmosphere is, and how to cover the coated side without trapping any air. A new product by Austin Thin Films is designed to solve all these problems.
I recently acquired a sample of their new product, Dichrolux, and was eager to try it out. My first impression was that it looked, felt, and even smelled like regular dichroic-coated glass. It had an orangey-yellow reflective coating with a light blue transmitted color. I broke the sample into small sections and proceeded with a series of tests. This is what I have found:
The first test was to see what would happen if I pointed up to a room temperature piece of the Dichrolux and placed it directly into the flame. To my surprise, after a few passes in and out of the flame, the coated sided did not splinter or even fly off of the glass. I then turned the piece around so that the coated side faced the flame. Still, nothing happened.
The second test was to heat the glass hot enough to bend. I heated up the sliver much like I would a clear rod, until it was glowing orange, and then bent it into a curve. The coating not only stayed on the glass but it also gained a shimmery satin-like finish that was not grayed or burnt.
The last test: coating a cobalt rod with the Dichrolux. Taking another sliver of the dichro, I pointed up to it and, with the coated side to the flame, striped it down the side of a cobalt rod and gathered the section into a ball. After the ball cooled to where it was no longer glowing orange, the dichro was still not burnt - not even on the edges.
What does it take to destroy the coating, I wondered? Could I make a marble out of pure dichroic coated glass? Sadly, the answer is no. When heated into a gather, the coating does “burn” off. The glass will start to fizzle before the dichro does. As it is heated past its limit, which I am told is around 4,500 degrees (well above the melting point of borosilicate), the coating doesn’t burn in the traditional sense – it kind of melts. The best way to describe it would be to compare it to burning off fume: it has layers to it. I held a piece of the dichro in the flame until it started to gather. At the edge of the cool side of the gather there was a gradient of color as the coating disappeared. This is not to say that it does not flake off, because it does. If shocked, by passing through the flame quickly, it will flake off just like any other dichroic coated glass. Dichrolux will turn gray if heated past its limit when incased. When I repeated the last test again for a shop mate I pushed the Dichrolux too far and it did turn that white, ash-gray that dichro does, but it should be noted that I did get the cobalt almost white-hot.
I would highly recommend this product to both beginners and advanced lamp workers. Its high melting temperature will allow the beginners to experiment with dichroic glass and achieve positive results with little frustration. Advanced lamp workers will find this product a great asset in cutting down on prep work and in saving time for completing a piece.