Friends-- I feel like a real newbie asking my question, but I had a
new and unpleasant experience I don’t understand. I don’t do a ton of
casting in my own work, but have never really had much trouble with
it, or with teaching basic casting technique to my students. The
other day, I had a student doing a cuttlefish casting, and she called
me because she had been heating her silver (mostly clean scrap, tiny
piece of old cast silver) for a long time, and it wasn’t melting. I
added a pinch of boric acid, and helped out with a second torch. The
silver melted, and she was clumsily maneuvering the crucible into
position, when the silver “froze”, and no amount of heat would get it
to liquify again. Was this the result of overheating? I’ve come
across warnings against it, but never heard what constitutes
overheating or what the results would be. Can I redeem my pocked
pebbles of silver? By the way, the silver wasn’t blackened, didn’t
look abnormal in any way. Pickled up to the right color. Thanks!! –
This has happened to me. When I investigated it was because my oxygen
or acetylene tanks were very low. Refilling immediately solved the
problem.
I certainly know of no additive (metallic or otherwise - or am I
forgetting platinum?) that will raise the meting point of silver. I
wish there were one sometimes!
Had this happen to me. I seemed to have plenty of heat on it–2
torches also. The student had gotten it to the slump stage (about a 2
oz. melt), but no further. With the addition of 2 torches, it
liquified, but didn’t ever real move like it usually does in the
liquidus state. Didn’t pour well, definitely didn’t mold well. Took it
home and used my husband’s big welding torch and rosebud on it. No
problem!
In class we were using propane/air, and then added a small
propane/oxy torch to it. I think what happened was it wasn’t enough
heat for the mass, especially after the slump. The heat couldn’t flow
around like it does with grain, because it was partially fused
already. When it got to the molten stage, there still wasn’t enough
heat to bring it up to the liquidus stage, so it froze.
My husband’s welding torch is acetyl/oxy and the rosebud tip was
probably overkill. But I was determined it was going to melt. It did,
and in very short order. So, it might be worthwhile to sweet talk a
friend with a more powerful torch to help you out, to at least get it back to grain.
before melting those old silver spoons, check around with antique
shops. Some of those old spoons are discontinued patterns and you
should be able to get more for them than the silver is worth, as
often collectors are looking for them to fill out sets. Then you can
decide whether to sell them or to melt them. Just a suggestion. Alma
Be sure to check that the silverware is marked with either 925 or
sterling, as it might just be silverplated. You may also want to
consider cutting off the decorative ends to use as ornaments that you
incorporate into other jewelry.