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Transparent red and yellow in a pot melt?

For discussion of processes related to using Bullseye glass, including kilnforming and kilncasting, torchwork, blowing and stained glass.

Transparent red and yellow in a pot melt?

Postby michaelcmace » Sat Jul 14, 2018 10:23 am

I have a question about the use of transparent red (1122) and yellow (1120) in pot melts. I'm planning to use about a dozen colors of Bullseye glass in a melt, including about 5% by weight of transparent red and yellow.

The Bullseye site warns that these colors may opalize or become incompatible at high temperatures. A pot melt goes to 1680F and holds there for 90 minutes to make sure the pot empties. What exactly does "become incompatible" mean? I don't mind if the glasses opalize or bubble because that sort of stuff happens all the time in a pot melt. But are those glasses also at risk of changing their COEs, and could they cause the finished melt to crack? That would not be fun.

I'd appreciate any advice.
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Re: Transparent red and yellow in a pot melt?

Postby marykaynitchie » Tue Jul 17, 2018 1:24 pm

The Bullseye project video with the glass under conditions most similar to what you want to to is our Boiled Glass video (available by subscription): https://videos.bullseyeglass.com/videos/boiled-glass/

In the discussion thread for this video, http://www.bullseyeglass.com/forum/view ... t4737.html
Ted Sawyer, our Research and Education Director, makes this comment:
With the exception of those glasses that we caution against - the transparent cadmium reds, oranges and yellows, almost any glass will work in this process - so it's really a matter of taste what you chose to use. In making this video we made props combining 0349 and 0303, 0120 and 0125, 0164 and 0303, 0216 and 0221, and 0349 and 0124 among many others.


Would you consider using opalescent versions of red and yellow? Because your transparent reds and yellows will possibly both opalize and change in compatibility. I would advise against it unless you have a high tolerance for and appreciation of experimentation.
Mary Kay Nitchie
Bullseye Glass Co.

Subscribe to Bullseye kiln-glass videos at
bit.ly/BullVideos
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