Non-Chemical Did I ruin my clay crucible??

[jjohio]

First melt of silver powder went great, 2nd time alot of silver stuck to the bottom..The poured silver didnt look as good either!! Is this crucible junk now?? Also, should I preheat to melting temp than add silver or can I put in cold silver with cold crucible and let heat up together?? Any help for proper procedure would be great!! I am using 2000 degree oven not a torch..Thanks, JJ

 

[jjohio]

Fused Silica Crucible is what im referring to...I sure hope to get more than 1 or 2 uses!!! Please help

 

[Geo]

if its just silver stuck in the crucible, you can remove this by soaking in dilute nitric acid.

 

[Harold_V]

First melt of silver powder went great, 2nd time alot of silver stuck to the bottom..The poured silver didnt look as good either!! Is this crucible junk now?? Also, should I preheat to melting temp than add silver or can I put in cold silver with cold crucible and let heat up together?? Any help for proper procedure would be great!! I am using 2000 degree oven not a torch..Thanks, JJ

It's not clear that you're using a crucible, not by the description. Is it a melting dish?

If so, it's pretty hard to ruin one from use. If all else fails, it can be heated to about 2,000°, then soda ash added. That will liquefy the old flux so it can be poured off. Repeat that process a time or two, adding some borax as well. Stir with a carbon rod as required, to fully dissolve all of the old slag and metal contained within. In the end, it's possible to restore the dish to like new condition, although you will have dissolved some of the dish in the process (soda ash and quartz equal glass). You can repeat that process until you have thinned the dish until it's too thin to use safely.

Edit:
I suggest you pour the molten slag to a cone mold. That way you can easily recover any values contained within. They will be found at the bottom, and easy to remove from the slag.

Harold

 

[jjohio]

Ill see if I can get my wife to help me figure out how to post pics on here..that way you can see what im sayin and what they look like

 

[jjohio]

I have some Borax laundry soap in a white powder?? that work or do i need pure borax powder??

 

[Harold_V]

I have some Borax laundry soap in a white powder?? that work or do i need pure borax powder??

That should work just fine. The only problem with such borax is it contains water, so it froths like crazy, and is easy to blow around with a torch. If you can find anhydrous borax, or borax glass, it's much nicer to work with. It doesn't froth and blow away with a torch.

Harold