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  #51  
Old 01-04-2019, 07:55 AM
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Empowering yourself doing it is worth the trouble. I still remember the first day I mixed a raw formula. It was Dudley's. Just an amazing feeling to realize that you really can do this. At that time, I mixed in an open barrel with my hands.

It opens up your world.
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  #52  
Old 01-04-2019, 10:01 AM
Eben Horton Eben Horton is offline
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Quote:
Originally Posted by Pete VanderLaan View Post
Empowering yourself doing it is worth the trouble. I still remember the first day I mixed a raw formula. It was Dudley's. Just an amazing feeling to realize that you really can do this. At that time, I mixed in an open barrel with my hands.

It opens up your world.
Well.. the recipe obviously said “mix well by hand”
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  #53  
Old 01-04-2019, 10:24 AM
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It's really a great way to start. You can buy 20lbs of the materials at any pottery. You need a decent scale and a bucket. Mixing with your hands really does work, not as well as a mixer but it works. It just lets you know you can make your own glass.

To me, that's empowering.

You need Silica, soda ash, Potassium carb, calcium carb ,sodium nitrate and some antimony oxide. The antimony may not come from a pottery but Universal pigment certainly has it. Mix a formula, throw it in a pot that's at least 2200F, let it melt and go flat, add more, wash rinse repeat. It takes about 8 hours after the last charge. Keep it at least 2200F. You'll have glass the next day. Add metallic oxides for color at about .1 percent max.
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  #54  
Old 01-04-2019, 10:40 AM
Art Freas Art Freas is offline
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Wonder if one of these would work for mixing.
https://www.amazon.com/Scepter-04239...rb_top?ie=UTF8
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  #55  
Old 01-04-2019, 01:46 PM
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Pete VanderLaan Pete VanderLaan is offline
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Henry Summa initially used something much like that in the early days when he was in New York. Cheap, fairly effective, takes up no space. Our little 7 inch crucibles don't cost much and if you prefer, Assay pots cost even less. My first pot furnace was built in a 55 gallon drum sawed off with a kast-o-lite 30 lid. Really low tech.

As to the mixer, the proof is in the pudding. It melts or it doesn't or something in between but the glass is talking to you. If you consider the cost of color rods compared to the cost of DYI , you'll be floored. Further, you'll make glass that doesn't look like everyone else's. The copper blue I'm using right now is absolutely electric and incredibly simple.

Read the stuff I wrote in Glassnotes IV on batching. It's a simply guide to doing it.
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  #56  
Old 01-05-2019, 02:41 PM
Lynn Read Lynn Read is offline
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Quote:
Originally Posted by David Patchen View Post
You might hit up George Bucquet--he makes some beautiful opaline glass.

http://www.georgebucquet.com/
Thanks for the Suggestion. I talked to him last week and he had some great advice and using MCP. Mono Calcium Phosphate.
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  #57  
Old 01-05-2019, 03:13 PM
Lynn Read Lynn Read is offline
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I wanted to share the results from my tests melting Phosphate white.

I am working with Spruce Pine Batch W/er87. Melting in an electric furnace with 50 lbs test melts at 2350 for about 4 hour melt, drop to 1900 for 4 hour soak and back up to working at 2130. That can be adjusted I think.

First tow melts with STPP Molecular FormulaNa5O10P3 Did not have any visible opalescence. My third test worked but was not an ideal system.

50 lbs SP batch
907 g STPP

Image #1 Full reheat - After a started Bubble is allowed to cool, the second gather and a full reheat caused the density to develop.

Image #2 Fresh gather cast and pressed. no reheat

Image #3 Spot heat with hot torch. My favorite so far

Image #4 started bubble allowed to cool and gathered with a limited reheat

Image #5 Spot heating with Torch on cast glass.

Amazing the variation heat has on this glass.


Does anyone have recommendations on getting the phosphate to strike on the cool down vs the reheat? I want to use this is casting /press molding but I do not have the option of reheating my castings without loosing the shape and texture. See image 5 for best results.
Attached Images
File Type: jpg Full Reheat.jpg (26.6 KB, 56 views)
File Type: jpg Fresh gather casting and pressed, no reheats.jpg (29.4 KB, 50 views)
File Type: jpg Spot heats with hot torch.jpg (31.5 KB, 49 views)
File Type: jpg Gather over and limited reheat.jpg (26.5 KB, 46 views)
File Type: jpg Spot heat on cast glass.jpg (25.6 KB, 51 views)
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  #58  
Old 01-05-2019, 05:31 PM
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Pete VanderLaan Pete VanderLaan is offline
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What Mark did in the "Ladder to the moon group was to cast the basic phosphate material and then press a "ladder into that mold. That caused a chill. Then the casting continued and the interface was opalescent.
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  #59  
Old 01-05-2019, 08:53 PM
Jordan Kube Jordan Kube is offline
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Bravo Lynn! That's the stuff!

Try removing your pieces from the mold after they've chilled and then hitting them with a hot torch on a turntable before boxing. Intense heat that won't necessarily cause you to lose your form.
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  #60  
Old 05-16-2019, 12:51 PM
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Ed Pennebaker Ed Pennebaker is offline
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dicalcium phosphate

I am cleaning out my batch room and came across some chemicals I procured from the old Southwestern Glass plant. One of them was dicalcium phosphate. I'm not sure of the chemical formula and searching for it has just confused me. CaHPO4 (calcium hydrogen phosphate)?, Ca2O4P+?. Using the "Potter's Dictionary of Materials and Techniques" they only list "calcium phosphate" in their table of mineral constants as Ca3(PO4)2 which shows up as the same thing for tricalcium phosphate in searching the internet or also Ca5(P3O10)2 pentacalcium bis(triphosphate)?.

Conversion factors the Potter's book shows is .542 CaO and .458 P2O5. Is there a reliable source for conversion factors on the internet? I find all kinds of chemical formulas under these different types of calcium phosphates and am not sure what to rely on. I would like to try some phosphate opals next time I fire up the furnace but I am down for the summer now. How would this "dicalcium phosphate" work for phosphate opal or am I better off making toothpaste out of it?
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  #61  
Old 06-18-2019, 12:59 PM
Dave Bross Dave Bross is offline
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You want to minimize the calcium so I would skip that...particularly since you can't easily nail down how much calcium is in it....and calcium is the source of all the problems if it gets much above what I put in the original formula.
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  #62  
Old 07-19-2019, 04:17 PM
Josh Bernbaum Josh Bernbaum is offline
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Brossphate 3.9%

So for the last melt here before shutting off my furnaces I tried a slightly modified Brossphate. I'm really liking the subtle effects and overall look of this glass. I saw just a little bit of the streakiness in the strike that some had warned about but it's much more clean and even than the mixes I had been doing with the SP as a base. I did try to mix the STPP with the lithium first which I think I'd seen as a recommendation. The changes I made to the Brossphate were substituting some of the sodium with potassium, using whiting instead of lime hydrate (don't have that here), and adding some cryolite. One question I had for those who can comment on this, is that the 0.4% addition of cryolite didn't seem to be noticeable, and if that's true maybe I didn't need it in the first place if I'm liking the strike from the phosphate? I mention this because, without any reheat or quick cooling, this glass was pretty damn clear. Really clear, actually, even without any erbium. I haven't mixed my own clears before, so I've had nothing to base it on, but the Short Mountain Silica/other ingredients I'm using must be pretty iron-free. I suppose I'd never have known because I've only ever added colorants to it in the past.

One other question is about my nitrate content. It was a bit seedy the day following the melt, but I had the luxury of giving it that day to 'mellow,' and on the following day when working with it the tiny seeds were still just slightly noticeable on larger gathers. I had 0.5% sodium nitrate in the mix, so would increasing that help fine those seeds any? I don't think Dave had any Antimony in his mix, but curious about that too.

All in all, it's still been really satisfying mixing a glass from scratch and getting to gather it and make things out of it. Still amazed all those powders can turn into something special. The photos don't show it, but in different light I can detect some purple, pink, and gold tones to the glass. Wild stuff..
Attached Images
File Type: jpg IMG_0682.jpg (35.1 KB, 25 views)
File Type: jpg IMG_0681.jpg (31.0 KB, 28 views)
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Last edited by Josh Bernbaum; 07-19-2019 at 04:25 PM.
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  #63  
Old 07-19-2019, 04:46 PM
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Pete VanderLaan Pete VanderLaan is offline
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to effectively take seeds back into solution reasonably quickly, you need more than the nitrate, you need either arsenic or antimony to flip the valence features. The trouble with squeezing this type of glass is the tendency to go slushy when cooled too long. I think it can effectively be done at 2075 but I'd use great care going below 2000F.

The nitrate does set up two things. Firsst it helps lower the melt temps and the other is the relationship with the multivalent antimony. Iron goes mutivalent as well but imparts colors, lots of them. Blues, greens, yellows...manganese might be another option but I don't see why antimony has to be avoided.

The cryolite really is lowering melts temps and while you may not "see" its effects, they're there making your life easier as long as the furnace is gas.
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  #64  
Old 07-22-2019, 10:49 PM
Jordan Kube Jordan Kube is offline
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In my experience the cryolite made the white pop a little more opaque than the typical opaline.
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  #65  
Old 07-23-2019, 09:10 AM
Josh Bernbaum Josh Bernbaum is offline
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Jordan, did you use more than 0.4% cryolite?
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  #66  
Old 07-23-2019, 11:31 PM
Jordan Kube Jordan Kube is offline
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It might have been .5%. I need to look at my notes and get back to you.
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