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Old 11-04-2003, 01:07 PM
Dave Bross Dave Bross is offline
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Join Date: Apr 2002
Location: Archer FL(near Gainesville)
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This glass is absolutely BEAUTIFUL!!!!!!!It has just a touch less sparkle/refraction than the Glasma but is very, very close to it otherwise. For me, it's nicer to work than Glasma.

and....

It does everything else I want really well too!!!!!

First, to answer Franklins' question, I did all the batching at 2000F. About an hour for the batch to go flat between charges.It took all day because I had to go do other things too. That night I cranked it up to 2200 and cooked it overnight. 8 hours to be exact. I lowered it to 2000F in the morning and it was squeezed out nicely 5 hours later.

It behaves very differently than other batch I've seen. It scared me while I was batching because there were what loked like dark unmelted lumps between the bubbles and I was worried that it wasn't going to melt down without silica stones or some other ugliness. I did use the 325 mesh silica flour.
Shortly after I turned it up to cook I was walking by and noticed a fizzing noise. When I looked in the furnace the glass was just bubbling away like a glass of freshly poured champagne and the dark spots were gone. So nice!

Now here's what else it does really well besides melt...

It is a wonderful torch working glass.

It has a lot of thermal shock resistance.

It has a combination of softness and working time that I really enjoy.

The powder is really a mess so I have to work on some things to make adding the batch a little neater. That's the only drawback so far and I can definitely live with that.

My quick version "shade tree" expansion testing, which consists of pulling threads of different glasses to compare against would seem to put it somewhere around 94-5. A little higher than FHC, very close to Gaffer, and a little lower than Spectrum.

I think a dilatometer will be a "near future" project.

I figured the oxide percentages on it and was quite surprised....

74% sand
12% soda
8% lime
6% potassium

That's a lot of sand. I'm thiking this should actually be quite durable because of that?

Question for Pete...

For historical interest if nothing else, why did you go from this recipe I just melted to:

63.25 silica
20.25 soda ash
9.06 Hydrated lime type N
2.18 Borax 5 mole
5.25 Potassium carb
100 grams antimony oxide
130 grams potassium nitrate.

and....

50 sand
20 1/4 soda ash
9 1/16 hydrated lime type N
5 1/4 Potassium carb
3 3/16th Borax 5 mole.

as a color base and clear? I haven't figured the percentages yet but it looks like the only major change is the borax?
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