Melting and silver casting

Are you doing investment casting, or ingot casting from slag and scrap? If your feed stock is slag and scrap then you can expect a considerable amount of "garbage" in your end product. Either way, I would recommend forcing Nitrogen or Argon through the molten silver to draw out any latent oxygen.

Mr Fernandez

I'm also having problems with silver casting.

I work for a jewelery silver designer and our problem are small cavities on the silver pieces produced in rubber molds.

We use a sterling silver alloy (950)

I appreciate any help

Alberto Balaguer

Most silver casting problems result from too low a temperature.

1800-1865 dgrees F is optimum range for sterling.

Melting to make alloy batches should beeven hottereven hotter- say 1900degrees F.

Flux? You should be using boric acid, not carbon based fluxes. Especially with contaminated scrap!

To get deoxidizers, you shouldbuy a master alloy such as S-88 from

http://www.agkem.com/united.htm this has the deoxidizer already in it.

or sterling replenisher:

http://www.wgmmetals.com/casting_alloys.html

milo

Othe rdeoxidizer s include silicon and zinc, but we can't find ourcopy of the compleat metalsmith to confirm...

Hi,

molten silver will readily dissolve oxygen, so you will either need to cover the melt with a deoxidiser (carbon?, ...) or, better if available use vacuum melting and casting.

It is sufficient to use a prepump only, it has to be operated with gasballast valve open to remove the water vapor that is contaminating any vacuum system.

RHABE

Thank you everybody

We will implement your coments and actions to solve this problem.

Regards

When i pour the molten silver into ingots it has a black surface, i wanted to know if the silver was fine or pure 999.9 silver would this high oxidation of the surface still take place?

Silver does not react with oxygen even at high temperatures. But it does react with ozone (O₃, produced by electric motors) and trace hydrogen sulfide (H₂S) found in the environment. The dark tarnish often seen on silver surface mainly consists of silver sulfide (Ag₂S).

Is there anything technically "wrong" (impurities, sticking, etc.) with simply placing clean scrap sterling silver (say recently cast errors, or previously poured shot) into a bar mold made of clean cast iron and placing the whole thing into a leveled electric kiln capable of the sufficient temperature, heating it to 1800F and letting it cool down, in order to create stackable/reuseable sterling bullion bars? This would save the expense of relatively indurable graphite or clay crucibles, pouring losses, etc.

Thanks a LOT elitist DORKS!!!! A simple response like "NO don't do that" would have saved me a lot of time and money in experimenting. To show I am better than these SNOBS, and for future experimenters I add, "DON'T DO THIS"!!! It will not only ruin your silver, but also your iron mold as well (even if you pre-coat it with carbon soot). If I was a forum REGISTERED SNOB I could post a photo of what happens when you try this, but since I'm not, I can't. Not only does the silver bubble and spatter all over your kiln (even at only 1700F for Sterling), but also sticks to the iron mold (eventually removable with a large chisel with pieces of rust sticking to the silver), causes your iron mold to flake and decay and also sticks the iron mold to your nicely kiln washed (now ruined) shelf.

This forum is useless. Thanks for nothing!

Dear guest,

Those of us who are registered and sign our responses create a "brand" and traceability for our comments.

Anonymous advice is "worth-less" because you cannot evaluate the credibility of the poster.

I can understand your frustration, but it is hardly sporting to paint those of us who have an established history of giving great advice "elitist dorks" based on the results of having following bad anonymous advice from an unknown party.

The key issue with the internet isn't finding information, its sorting out the crap from the good information.

The first big clue that something is Crap is its anonymity- that you can't know who it is that is dispensing it.

S'OK, we'll be here to tackle the next problem that some "guest" needs an answer for, and because we are identifiable, it will be great advice. And, I believe, at no cost...

milo

Ever stop to think that possibly none of us "elitist dorks" even KNEW that would happen? But now, thanks to your input, we DO! Lose the attitude, and come on back and register. We can always learn from each other.

ok, I am a dork. I understand that sterling silver is an alloy consististing of at least 2 metals and each metal has a boiling piont. I need someone with experience with the melting process and seperation of the metals without a shop disaster. this is very new to me. so far I have only melted lead and aluminum which were used entirely in their original content. thanks, rick

Well, I freely admit I do not have the expertise to advise you. I am documentably ignorant on this issue. But there are some folks here who might be able to assist, so I'll see if I can find out something.