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Old 01-14-2018, 09:45 AM
Dave Bross Dave Bross is offline
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Join Date: Apr 2002
Location: Archer FL(near Gainesville)
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Getting back to the glass color....

The percentage in the phosphate Jordan mentions requires multiple strikes (hot-cold-hot-cold) to get dense opaqueness. I first figured it out making furnace beads and that process had a number of strikes as a default. It can be made quite opaque with three or more strikes.

Coming out of the pot clear has other advantages. You can make multi layer transparent/opaque veils by repeat gathers with no reheats (not striking it any further).
I never got to it but I wanted to see what the minimum percentage of phosphate would be to just barely strike. I thought that would open up other avenues. Something like the old Fenton stuff that only struck when it touched the mold.

I have some distant memory that there is a ceiling on how much phosphate you can add. If you dig back in classics to the original post you'll find the link to the original Corning patent that tipped me off on this. I think it mentions a max on phosphate.

I'm laughing at the Brossphate name tag. Could this be my 15 minutes of fame?

No royalties required. I'm just an open source kind of guy. I never would have figured that out without all the other info that everyone posted here over the years prior to that.

As Pete says, potassium content in this glass does good things.

The phosphate is slightly dichroic too. If I'm remembering correctly, it's red for transmitted light, blue for reflected.
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