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I've read the French Vanilla will react with itself (but have yet to do do any testing) - are there others?

And, more in the category of idle questions: What is it about the interface between two pieces of the same glass that causes the reaction to occur? Is it a manageable reaction? I.e., can one manipulate the fusing environment to enhance or impede the reaction?

I've found this chart to be helpful:

http://www.bullseyeglass.com/methods-id ... chart.html

leaving the rest of your questions to the experts!

David Jenkins wrote:I've read the French Vanilla will react with itself (but have yet to do do any testing) - are there others?

I'm not sure I believe this. French Vanilla does change color at different areas during some firings, which can look like a reaction but is more likely caused by differences in the amount of heat work in different parts of the glass (i.e., the edges become whiter than the center). But I've never witnessed what I would interpret as a "reaction" with itself. Not even sure what that means.

And, more in the category of idle questions: What is it about the interface between two pieces of the same glass that causes the reaction to occur? Is it a manageable reaction? I.e., can one manipulate the fusing environment to enhance or impede the reaction?

The reaction is a chemical one, such as copper with sulfur. The amount of chemical differs from glass to glass (and even from sheet to sheet of the same glass). Bullseye's chart tells us which glasses have which chemicals, but doesn't suggest the amount of chemical in a specific style of glass. (The System 96 chart is better than Bullseye's in that it also tells us whether the style has a high level, medium level, or low level of the particular chemical.)

The reaction is manageable in several ways. First, the more surface area (or edge) in contact between the two glasses the stronger the reaction. Second, the higher the temperature (or the longer the hold) the stronger the reaction.

Maybe you are talking about the color difference between the inside and outside of the glass? It's not a reaction, but it is a color variation. Here's a quick blurb from BE:

http://www.bullseyeglass.com/french-van ... scent.html

Very viscous; will flow later and less than other glasses. Generally more sensitive to heat-history and more likely to show variation in color after fusing than many opals. When fired on edge, a clear distinction between outside and interior surfaces is commonly seen (a variation used by designers). This glass may become increasingly white with repeated firings. Consider using glass from the same batch for a given project.

Spectrum's Vanilla Cream is like this too, and I think probably a little more pronounced. (http://www.system96.com/pages/whatsnew.html)

Dana

Dana:

I think you nailed it. And I myself have seen the color variation due to repeated firings. So I guess I either heard wrong some place or other, or was just gullible enough to believe the reaction theory.