onondaga
posted this
19 March 2013
http://www.castbulletassoc.org/view_user.php?id=974>vmwilson:
One procedure that really helps to alloy bullet metals well is to melt the heaviest, highest melting temperature metal first by itself. when completely fluid then add, melt and flux each additional metal progressively to the lightest, lowest melting temperature metals.. In your case first melt the BHN-8 lead, flux, then add the super hard, melt, flux and last add the tin, melt and flux.
If you do this out of order you can get an oatmeal looking higher temperature mush floating on top that will be hard to get into alloy unless you use extreme temperatures that will oxidize a lot of tin that you can only return to alloy with a specific reduction fluxing method and fire.
Understand that if you mistakenly melted the tin first, you would have to superheat it to be hot enough to melt the lead into it. That is a mess, avoid that. the same will happen if you melt the superhard first and try to get the BHN-8 into it. Start with the BHN-8 and melt it first. Definitely don't just throw everything in the pot and crank it up. you would oxidize a lot of tin doing that and require a lot of heat to get the mix to melt and then reduction fluxing with fire to get the tin oxide back into alloy.
If you don't thoroughly understand what reduction fluxing with fire is and don't do it correctly, again you will have a mess with oxidized tin that looks like dross but is not and oatmeal floating on top that you may not be able to alloy without extreme heat and reduction fluxing..
The most common mistake is skimming the top and tossing a lot of tin out because it wasn't hot enough to flux in the first place. Tin oxide is a fine dust on top of a melt, not a heavy glop. If you have a heavy glop, you have not gotten your melt hot enough to flux....don't throw the glop out---that will ruin your formula. Melt it and flux it correctly till there is just dust. Even most of the dust can be reduction fluxed back into alloy.
Your 7.4 oz of tin should be added last. If you have to cut it to pieces, I find using an axe held in place and struck with a sledge hammer over a stump to work fine.
Gary
