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Lindyloo
20-11-2009, 08:35 PM
Before I tear my hair out, can some kind person help me. I have now managed to crack 3 crucibles. Here is a picture of the latest one. With the previous two, I got scared off before adding any silver (I had just put some borax in), and didn't continue with them. But with this being the third, I got fed up and just used it anyway, with no ill effects.

After cracking the first two, I spoke with Ben in the chat room, who suggested that it might have been because I kept them in the garage, and they were cold when I put the flame to them. So this time, I kept the crucible inside the house, then took it out, and waved the flame gently over it first to warm it up, before going in full blast. But still it cracked. What is wrong with me? :'(

723

geti-titanium
20-11-2009, 10:56 PM
Crucibles should properly be tested for cracks prior to use, a good ceramic crucible will "ping" when hit with a soft hammer while a damaged one will "thud".

Keep the crucibles in a dry place and pre-heat them and the metal to be melted. A little bit of moisture can cause the crucible to crack on heating.

minnie
21-11-2009, 12:53 AM
I have used cracked crucibles for ages and they don't break.Not ideal I know but they carry on.

I don't heat them and add silver, just put the silver in, sprinkle borax(it finds its place) and go for it.

I have never actually had a crucible break, if melting safely it would not be dire if it did.

Polly
21-11-2009, 08:45 AM
I agree with Geti, I suspect the crucible has got damp in the garage, :xmaswin:

Lindyloo
21-11-2009, 08:43 PM
Thanks for that info guys. Does that mean that the crucibles are porous? So how would you preheat them first before use?

minnie
21-11-2009, 10:47 PM
I don't, why do you have to pre heat?

Silver in crucible, borax dropped in, go.....

Borax melts down, flame chases silver, etc

Always go from cold crucible, even if cracked then it works.

barclaybear
22-11-2009, 09:01 PM
Probably a dumb question from a baby noob (if it is, sorreeee) but here goes .... what exactly is the purpose of a crucible??

BBear
x

Lindyloo
22-11-2009, 10:11 PM
The crucible is a heat proof container for melting metals inside ready for pouring into a casting mould. Also known as a scorifier.

barclaybear
23-11-2009, 03:12 PM
Ah ... excellent! Thanks Lindyloo.

And well done for answering the question I hadn't asked yet but would almost certainly would have had to have asked soon about what a scorifier was!!!

:ta: