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Old 04-14-2019, 02:41 PM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 22,272
Pete VanderLaan is on a distinguished road
SP color base has to be mixed well. That's A . B, is that it does not contain fining oxidizers making it easier to do colors with copper ans silver but it's a real downside.

I wrote my formula to accommodate tom on a secondary batch but I used better quality materials to do what I wanted.Subsequently it didn't cost less than SP87. My response is that I don't like making inferior products and I view SP87 as a limited glass. It does fine for blowing, not for casting. It is far lower luster but has a lower viscosity. I'm not in the position where I want to sell small quantities of my glass. Making my own work takes enough of my time.

There's no free lunch. If you want a glass with less viscosity, you need to engineer those results and the advantages will have disadvantages. I don't view Spectrum as a boon to the field given all the problems that came up as well. As to Oceanside, they have a long ways to go to inspire confidence.

If you indeed have mass issues in the kiln. Crash the kiln by opening the door until it hits 1100F.

I haven't read the material John refers to. If it was asserting 2%, that's a bit different than what Nick preached. I will continue to total the alkaline flux and divide by 8. Alumina is strange stuff. I have tech material from Vargin for enamels where the silica content is less than 50% and the alumina hovers around 11%
Where are we going and why am I in this basket?
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