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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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Pete VanderLaan Pete VanderLaan is offline
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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
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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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