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Re: alloying - Silver Nitrate test
Posted by Lyle Landstrom on January 04, 19100 at 20:16:25:
In Reply to: Re: alloying posted by joewizard on January 04, 19100 at 01:03:11:
I use just a little bit of Silver Nitrate dissolved in water. File off a clean bit of metal and put a drop of it on it. if it turns grey quick, then it's maganese bronze. It's also slightly magnetic. It's lots cheaper going and getting it this way than spending dough for certified ingot.
Ship propellers and threaded rod from water hydrants seem to work the best. The inside of old bearings (cages) that look brass are actually aluminum bronze and will not work. Silver Nitrate will not change color. Lots of other stuff that looks good won't react either. Only use what turns the silver nitrate grey.
This test also works to test aluminum for magnesium, but in that case, you don't want the metal as magnesium might ignite and you'll never be able to put the fire out.
For a few years I blended my own brass with copper and zinc. I got the zinc from a galvanizer or from an ingot supplier that sold "zinc balls" used as anodes in the construction industry. Melting the copper and adding zinc to it is very messy. Makes for a large greenish plume of smoke which you do not want to inhale. You need to cover it and degass with phospher copper welding rods. I don't recommend it as the Silver Nitrate method works and is cheaper.
Maganese bronze does not need to be covered and you don't have to flux it. It melts clean. You have to use large gates and choke the pour as it shrinks alot. I don't have experience plaster or shell casting with it as I do all sand casting but I don't see why it wouldn't work. You can also mix it with any silicon bronze alloy for whatever color you want. In that case the shrinkage isn't as bad. It will still flare when you skim it but that's OK. Wear dark eye protection as the flare is pretty bright.
I have to thank my friend MJ for this tip as he's the one that originally told me.