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Old 02-01-2018, 07:50 PM
Jordan Kube Jordan Kube is offline
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Brossphate opal 5%

So I melted this 5% opal the other day:

In pounds
Sand 7.3125
Soda Ash 2.38875
Potassium Carbonate 0
Calcium Carbonate 0.4125
Strontium Carbonate 0.675
Zinc Oxide 0.225
Alumina Hydrate 0.3375
Lithium Carbonate 0.075
Antimony 0.03975
Potassium Nitrate 0.075
Sodium Tripolyphosp. 0.93

Total 12.471

Oxides %
SiO2 66.86
Na2O 16.4
K2O 0.327
LiO 0.278
CaO 2.13
MgO 0.006
SrO 4.35
ZnO 2.06
Al2O3 2.229
P2O5 4.95
Sb2O5 0.365

Charged a few scoops at 2300 every two hours. Held at 2300 for 10 hrs and then down to 2150. It came out pretty scuzzy on top like you guys talk about some phosphates coming out. It was also pretty streaky in coloration and cordy looking. It blew out ok and the stuff I made into bar struck out beautifully after being picked up again, as always. As a note, I ground the STPP in a bullet blender in an effort to avoid some chunkies I was getting in the 2.5% melts. It also came out 4 points high after my educated guess on adjustment. Based on that and my percentages I'm thinking at least adding some silica is in order.

Any thoughts on cleaning this one up?
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Old 02-02-2018, 09:44 AM
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Pete VanderLaan Pete VanderLaan is offline
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I'd be inclined to simply replace that calcium with both zinc and strontium and the industrial sludge will stop. I had told you it has a tendency to be streaky and more phosphate would help there. While the silica is low, it's not that low. I assume you're allowing the stuff to get really cold before you try for the strike.

I don't particularly trust flame annealed Hagy seals.
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Old 02-02-2018, 12:21 PM
Jordan Kube Jordan Kube is offline
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Thanks Pete, I'll give that a try.

As far as flame annealing Hagy seals, it's only so they don't crack before I get them into the annealer. They just don't look right and don't give good information if they are not properly annealed.
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Old 02-02-2018, 02:16 PM
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Mine don't crack before they go in the box but I'm not six points off.

There are people who rely on flame annealing, an all around bad idea.

As to the phosphate. I'm not sure what that will do. It seems to me that you should be able to make the phase separation work using that alumina which is key in fluorine opals as well. I don't know if you remember when I described the streaks to you last year and you were curious. It's quite compatible and I've had that cup around for years now. The fact that it strikes on a reanneal confirms that there's plenty in there.

Bob Held first noted that up to 5% bone ash would stay compatible with your clear way back at the NCECA conference in 1968- pre GAS. But it had to melt at over 2400F. It was a true calcium monophosphate which is really hard to find now. 2300 seems a bit cold to me on that stuff you're doing. Give it another 25 degrees.
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Old 02-02-2018, 03:47 PM
Jordan Kube Jordan Kube is offline
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Hotter was my other thought. Stuck in a wire melter for now. I ditched the borax Dave was using too.
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Old 02-02-2018, 05:11 PM
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If you're ditching the borax then you need to use another method of keeping that melt easy. Heat helps but if the borax goes, then add more heat. Sodium nitrate would be where I would look for chemical help. . Lithium could be increased but it's pricey.
My original phosphate melts needed 2450F and very small charges. That was 1975.
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Old 12-19-2018, 11:58 PM
Lynn Read Lynn Read is offline
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Quote:
Originally Posted by Jordan Kube View Post
So I melted this 5% opal the other day:

In pounds
Sand 7.3125
Soda Ash 2.38875
Potassium Carbonate 0
Calcium Carbonate 0.4125
Strontium Carbonate 0.675
Zinc Oxide 0.225
Alumina Hydrate 0.3375
Lithium Carbonate 0.075
Antimony 0.03975
Potassium Nitrate 0.075
Sodium Tripolyphosp. 0.93

Total 12.471

Oxides %
SiO2 66.86
Na2O 16.4
K2O 0.327
LiO 0.278
CaO 2.13
MgO 0.006
SrO 4.35
ZnO 2.06
Al2O3 2.229
P2O5 4.95
Sb2O5 0.365

Charged a few scoops at 2300 every two hours. Held at 2300 for 10 hrs and then down to 2150. It came out pretty scuzzy on top like you guys talk about some phosphates coming out. It was also pretty streaky in coloration and cordy looking. It blew out ok and the stuff I made into bar struck out beautifully after being picked up again, as always. As a note, I ground the STPP in a bullet blender in an effort to avoid some chunkies I was getting in the 2.5% melts. It also came out 4 points high after my educated guess on adjustment. Based on that and my percentages I'm thinking at least adding some silica is in order.

Any thoughts on cleaning this one up?
---
Hey Guys, Jordan and Pete,

I have been reading this thread and wanted to ask if you think this Sagahara glass is a Na5P3O10 opal (STPP)? It has so many amazing hues of blue and golds but the density is so slight I would imagine it must be only .5 %- 1% max phosphate. Based on the images that Jordan posted at 5% I would be far to dense.

I want to run some test melts but trying to gain some feedback first. I will be press molding the glass with a wall thickness of 1.2" - 3/4" thick so I need to limit the saturation. I will be cycling the glass through a cold work process and a second firing for my final fire polish. I am sure the duration of heat cycles will effect the opacity with this glass. I am hopeful that I can get a nice pale smokey white.

Any advise would be helpful in regard to % of STPP or strategies to get the shift if warm and cool tones. Maybe it is just the shape of the glass refracting color.
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File Type: jpg Sagahara opalescent vase.jpg (24.5 KB, 38 views)
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Old 12-20-2018, 08:51 AM
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That density is probably correct. In the STP melts I've done, it is periodically really streaky stuff, almost like a comb was run thru it but if reannealed, it really took on opacity. Press molding will no doubt do something unexpected but the re strikes matter a lot. Streaking seems to be a repeat concern with it. Kenny wrote me about that last week and I really didn't have great insight. Keep the calcium as low as humanly possible.
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Old 12-20-2018, 10:54 AM
Dan Vanantwerp Dan Vanantwerp is offline
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Looks like silver fuming to me. Almost wonder if that's some boro tubing.

So far my attempts have not yielded as much "fire opal" as just opal. The red only came out when overlaying a chalcedony color. Very interesting look.
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Old 12-20-2018, 01:33 PM
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I would be very surprised to find that was not a generic phosphate opal actually.

I have a large piece of Mark Peiser's in our bedroom and its a monolithic casting six inches thick by about 30 inches of a Phosphate glass, which is all Mark works with. During the day it changes from translucent white to yellow to blue and then to red.

The thing that was driven into me over the years was how important the modifiers and stabilizers are in a base glass. They totally determine the color with few exceptions. Calcium is not your friend when making color. Neither is sodium.
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Old 12-20-2018, 07:08 PM
Jordan Kube Jordan Kube is offline
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You will probably need to let it cool and then heat it back up after pressing to get any color out of it. You are really going to be able to take advantage of the beauty of this glass with those thicknesses. I would start at 2%
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Old 12-21-2018, 08:00 PM
Jordan Kube Jordan Kube is offline
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Mono Potassium Phosphate would perhaps be a good choice then Pete?

KH2PO4
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Old 12-22-2018, 08:37 AM
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I have no idea. You need a little calcium. Emphasis on little. I don't actually know the structure for such a material. (PAUSE)
OK, here's calcium monophosphate: Ca(H2PO4)2 divalent
Here's potassium phosphate: K(H2PO4) divalent

phosphorous : valence 5
Phosphate combo valence 3

worth noting in the pentavalent form (Ca5) it appears to grow apatite, not your friend unless you love bone snot.

So armed with that info, I think it might be worthwhile to try it although it sounds like a fairly obscure compound to be found in your average chem supply warehouse. I think that really breaking it down would take a trip into mole chemistry. Count your atoms.

None of this clarifies much for me. Melt some.
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Old 12-22-2018, 02:56 PM
Jordan Kube Jordan Kube is offline
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A little obscure, sure. Food and fetilizer chemicals. Not our usual source for supplies. I was able to find the Pot phosphate in 50# bags for $2.38/# delivered here https://www.greenwaybiotech.com/coll...ant=1557348161

I could not say the same for the Cal monophosphate. It is a pretty common food additive so someone has it for cheap.

You know me Pete, I'm always happy to try something rather than speculate. Thanks for the breakdown.
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Old 12-22-2018, 04:36 PM
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I was unsuccessful on the Cal monophosphate which surprised me so I went with the STP and have 100 lbs which will take me to the end of the line. The STP does inexplicably streak, even to the point of leaving what look like fingerprints at times. On a reanneal, it's dense and has great color. The trouble I see with the fertilizer grade is the tramp stuff.
It turns out your bones are largely apatite in the pentavalent state. A state you want to stay away from. Right now, I'm melting copper blues and they are so stunningly beautiful and so stupid easy.

Report back on the pot phosphate. It's a very interesting idea. That's not a terrible price although getting it back east might cost.
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Old 12-22-2018, 06:15 PM
Jordan Kube Jordan Kube is offline
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Free shipping.

I'm not currently melting batch but I do have a place in mind that might accommodate me. If I wasn't so taken with machining at the moment I'd probably have a little test furnace going by now.

Yes to the copper blue. Really the most beautiful blue out there, isn't it?
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