elementcollector1
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Removing Cobalt Glass from Crucible
I got a crucible for free the other day. It's a good'un, too, capable of going up to at least 1200 C without a problem. Looks to be made of alumina,
judging by how many were meant to just be 'thrown away' according to the professor who gave it to me.
My problem is, this particular crucible was used for making cobalt glass, and as such still has a coating of the latter across the bottom. I'd like to
remove this, but I'm not sure how - would molten NaOH be sufficient, or would that attack the alumina of the crucible?
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aga
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I bought 2 alumina/silicon cruicibles and stuffed a load of NaOH solution into one of them, which sat in there for a few days.
Cannot remember why i did that.
The NaOH worked it's way through the entire structure..
On the outer surface there were mosaic-like lines where the NaOH had penetrated all the way through.
On firing, it exploded.
[Edited on 9-4-2016 by aga]
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elementcollector1
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Quote: Originally posted by aga  | I bought 2 alumina/silicon cruicibles and stuffed a load of NaOH solution into one of them, which sat in there for a few days.
Cannot remember why i did that.
The NaOH worked it's way through the entire structure..
On the outer surface there were mosaic-like lines where the NaOH had penetrated all the way through.
On firing, it exploded.
[Edited on 9-4-2016 by aga] |
...Welp.
Not doing that, then.
Any other suggestions? Composition of the glass is approximately
B56Si47O214Na30K20Ba6Zn5, according to my professor.
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hyfalcon
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When removing glaze from porcelain, ammonium bifluoride has worked for me, but be careful, it's still nasty stuff.
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j_sum1
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I thought you said it was cobalt glass?
I don't see any Co there.
:confused:
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unionised
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If it's a (largely) borate glass it might dissolve in molten borax.
Leftover borax can be washed out with warm water.
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elementcollector1
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Cobalt is there in trace amounts, i.e. 0.014g per 300g batch. This is actually enough to color the entire glass a strong purple-blue.
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