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Old 2011-07-11, 8:45am
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SilverRiverJewelry SilverRiverJewelry is offline
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Okay here is the part to do with cracking. And I tend to forget to adjust my torch when I work with this glass, I am going to have to post this where I can see it on my bench lol.

The one thing I wanted to mention is that there are a number of factors that can cause cracking. Obviously, incompatibility is one. And when people have a cracking problem, they often assume it is a compatibility issue, especially when they are careful not to do other things that can lead to cracking. The point is though, most of the combinations you have tried without success, we have tested and retested successfully. Some of those we have posted on our website. The only conclusion that can be reached if this is the case is that there are other factors involved that could be leading to your cracking problem other than compatibility issues.



Let's consider this. Below is a picture of the Devardi bi-color rods we sell:









http://www.devardiglass.com/Chevron3s.JPG

All of these colors have an Op. White core. If the transparents were incompatible with Op. White, the factory would not be able to make these rods. When you make a bead with these rods, the white thoroughly mixes with the transparents, and without cracking. Again, this would indicate the Op. White is very compatible with Devardi transparents.



Because we have had success with the combinations you mention, and because these bi-color, opaque white core rods are readily available, this must lead us to conclude your cracking is caused by something else other than a compatibility issue. I would assume, as skilled as you are at lampworking, that you heat the bead properly before annealing and then immediately anneal. I think you even mentioned on LE that you do this. So it is unlikely that this is where the problem lies.



However, there is another factor involved with Devardi Glass that a lot of people overlook that can lead to cracking. People who have been lampworking for a long time with various brands of glass are often used to a particular heat setting on their torch, usually a midrange oxygen/propane mix. Two things though, one, Devardi Glass is a much cooler temperature glass (meaning it is formulated to be worked cooler) and two, it is a stiffer glass than most other brands. This stiffness can lead people to overheat the glass. People who are used to glass that flows easily often try to make Devardi Glass flow the same. This requires more heat since Devardi will not flow like say Moretti at the same temp. But to raise the heat that high can ruin some of the properties of Devardi glass, which can lead to cracking later. Of all the factors that can cause glass to crack, I would way this is the number one issue with Devardi. It is a problem since Devardi entered the scene long after people got used to working other, more pliable glass at hotter temperatures.



So the bottom line is, be very careful not to overheat the glass. You can use an Oxygen/propane setup. We do. But just cut the oxygen down so the flame is on the feathery side. If you run a Hothead type torch, be careful even with this one. It too can reach temperatures that can “scald” Devardi Glass. Work the glass with tools to shape it, rather than try to heat it to make it flow to shape. Be careful not to make it flow like Moretti and others. This is not correct for Devardi Glass. I think you will have better success with your combinations at lower temperatures. I can relate to this, because this is what I ran into when I first started with the glass myself. It took some time for me to realize I had to reduce that flame.
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