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Cords form in a crucible of glass where the crucible is hotter than the glass inside it. As I said, the chemical reactions take place at the hottest point. I don't think those cords will effect your ability to grind and polish the surface. If they do, it would be a far sight less than a bubble in t...

not necessarily. It just isn't a guaranteed basketball slam dunk with the clarity and non distortion you require. Now if you had the ribbon of optical glass that used to flow through the Stuben factory, you could have made some mighty fine lenses. Please note light will not travel thru my glass. It...

Kevin Midgley wrote:....... cords !!!!!!

So I will wind up with cords? I'm still a learner here! 2 years playing part time!
Ron

The best way to eliminate bubbles is to start with a single piece of glass that at the hottest point. Pouring molten glass in to a mold is actually a single particle. The last line is an interesting statement------ It appears to tell me I can melt glass in a furnace to a bubble free condition and t...

I came up with an idea in my sleep --My goal is casting or fusing glass for telescope mirrors. I am looking for opinions here
How would casting or fusing in a vacuum chamber work with regard to getting rid of bubbles?
Ron

twin vision glass wrote:May I strongly suggest a block of Schott Crystal. So beautiful . NO bubbles , and flows like butter. Les

Who sells this? And what can I expect to pay for it?
Ron

I've use model clay that doesn't dry - so you can use it over again. Then obtain fiber paste ready to use in a pail (I went to a wholesale refractory supplier, Smith - Sharpe in Minneapolis). This stuff is super sticky but can be placed over the clay and, once hardened, becomes a wonderful refracto...

If I am casting a glass blank 14 x 1.5 inches and I soak at temperatures somewhere between 1600 and 1900degrees will the bubbles "eventually " all rise to the top? 24 hours time? Or will more be created by some volatile substance in the spectrum 96?
Ron

Ron, as I understand it, you're not looking for perfect transparency since these blanks will become mirrors anyway, but a hole on the surface would be a problem, right? Spectrum's nuggets are for casting and blowing. They don't need pre-melting if you're casting. If you're blowing, the premelt/batc...

Ron, as I understand it, you're not looking for perfect transparency since these blanks will become mirrors anyway, but a hole on the surface would be a problem, right? Spectrum's nuggets are for casting and blowing. They don't need pre-melting if you're casting. If you're blowing, the premelt/batc...

The difference is significant. In furnace casting you take the glass to @ 2300ºF and let it sit until all the bubbles dissipate. This is like taking the lid off of a carbonated soda and heating it. 2300º glass is quite hard on refractories and elements. Fusing kilns are not made to work long in thi...

Did you purchase System 96 billets, which are made for kiln casting, or System 96 nuggets, which are made for glass blowing? I'm not sure how well the nuggets would perform if used in a casting environment without being remelt in a furnace first. Perhaps someone else on the board has experience wit...

I took you folks advise and picked up a 50 pounds of spectrum 96 nuggets. I plan to melt my first experimental telescope mirror with the spectrum nuggets into a 12 in stainless mold about 1.5 in thick. Can someone with more experience with this glass suggest a maximum target temperature to start wit...

First, stop using chicken wire at any temp. Every time I've tried it I've gotten chicken wire-patterned flashing. Second, plaster isn't made for those temps. As I mentioned in the other post, talk with R&R or Remet about the slurry systems bronze foundries use, or have ceramic or special refrac...

Peter Angel wrote:I gave you a reply in another post about using stoneware or porcelain paper clay that you can fire up to 2372F/1300C and use without kiln wash/separator but you completely ignored my post.

Peter
I Apologize I missed it. I am intrigued. Please enlighten me. This is new territory for me
Ron

I have a 21 x 3/4 corderite round shelf with the holes thru it. I was wondering how fast of a rate per hour I could fire it at?
Ron

I need help here. I currently use a round ring like mold made of 50-50 no.1 plaster and 200 mesh silica with chicken wire embedded to cast my telescope mirrors. I am experimenting at 2100 degrees. I don't need fine detail in my mold. I would like to strengthen my molds and decrease cracking. Can I a...

If you go to the website I mentioned, and click on the studio link, it shows other photos. They made a very large boro lens blank. shows the kiln they made it in too. I also know of a guy with a defunct ceramic lab that has some very large very high temp molyD bell style kilns for sintering ceramic...

I would be looking at either Spectrum cullet, or Blenko dalles or cullet. Both of these are inexpensive and the glasses have much better casting characteristics than float glass. My source for float glass buys a lot of their glass from one factory, however they also buy from others. I usually buy m...

I would be looking at either Spectrum cullet, or Blenko dalles or cullet. Both of these are inexpensive and the glasses have much better casting characteristics than float glass. My source for float glass buys a lot of their glass from one factory, however they also buy from others. I usually buy m...