Devit on Blue Bottle Glass
Devit on Fused Blue Bottle Glass
Once you start cutting up bottles and fusing them back together, youwill notice that blue bottle glass has a tendency to devitrify in a seemingly random way. Take this little star for example. Some of the glass pieces have fairly heavy devit and some have none. If you look closely you can see a batch number etched on one of the glossy strips. This gives us a clue about what may be happening. Batch numbers are always etched on the outside of bottles.
After a ton of testing, I discovered that when the blue glass is fired curved side up, that is, with the INSIDE of the bottle up, it is much more likely to devitrify. I tested with a ton of different blue bottles, as well as other colors. Here’s a selection of the color tests:
The vertical glass on all tests was curved side up, the horizontal piece is curved side down. Although some of the other colors do have a very light devit, the cobalts are all quite frosted. (Click here for a large format zoomable version of this photo)
The easiest way to avoid this is to keep track of which side to fire up. It sounds like it would be a pain, but it does make a huge difference.