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.



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