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Old 04-15-2019, 02:35 PM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 21,860
Pete VanderLaan is on a distinguished road
I live in the land of no free lunch. We all wish glass could solve universal problems instead of being the universal solvent. Most people think of glass as having afixed expansion at a fixed temperature and it does but it keeps on expanding which is why it's impossible to fill a pot to the brim. What looks full at 2300F is not what it will look like at 2000F.

Anne Robinson is the key to your casting. You need to determine exactly how much glass you need to fill that mold, allowing just a bit at the top sprue. That can be done and Henry describes it wll in Glassnotes IV as a simple displacement issue. A lot of people use rice to get there.

Spruce Pine color base is simply SP87 without the antimony or the nitrates. In making many colors that rely on colloidal suspensions, getting oxygen out of the glass is key to success. Other issues do come up but that's a major hurdle. Tom took the color base to heart after taking my first color class over fifteen years back. It helps to count your oxygen in your glass and to do that you have to work from the raw chemistry.

I only advocate making your own glass these days so you know where your glass comes from but you have to always keep in mind what brought you to the swamp. Making the piece is the important thing. The tech part will try to hinder you and there are not many tools on the market that make this easy. You just get that appearance. It is never easy

I can't say about your crucibles, I don't know what they are. Assay crucibles have a place in the show as do high purity ones. Iron can be an influence in color but you have to be at a pretty fussy place to notice that.
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