Is this a suitable source of copper for cast boolits?

[jethunter]

Would this alloy be suitable to use to get some copper in to a lead boolit alloy? 98% copper, 1.75% tin, 0.25% zinc

The % zinc would be considerably less than 0.25% when it's finally mixed with the lead - less than .01% if i'm using the right math. Is that too much zinc or acceptable?

[badgeredd]

Would this alloy be suitable to use to get some copper in to a lead boolit alloy? 98% copper, 1.75% tin, 0.25% zinc

The % zinc would be considerably less than 0.25% when it's finally mixed with the lead - less than .01% if i'm using the right math. Is that too much zinc or acceptable?

jethunter,

It is my opinion (for what it is worth) that you will likely have trouble getting the copper into your alloy. The reason I say this is in my experimentation, tin helped to get the copper mixed into the alloy. I would love to get some of that alloy to add to my babbit to bring the copper content in the babbit up to 6-7%. Like I said initially, this is my opinion.

Edd

[runfiverun]

hmmm.
ed has outlined the way he adds copper to tin to make a babbit.
it's more efficient than any of the way's i was doing it.
the one way i was doing it worked well, but it is too dependant on scrounging enough of the base alloy, and the copper content isn't all that predictable.
i think your "brass" there would work pretty well for adding into a tin solution to make a babbit to alloy with.

[jethunter]

Thankyou gents, I was hoping to use that alloy with babbit but not sure if that zinc content was a deal breaker. That metal is actually Canadian pennies, 1978-1996 issue. After '96 the mint started using an alloy that was mostly zinc instead of copper.

[badgeredd]

Thankyou gents, I was hoping to use that alloy with babbit but not sure if that zinc content was a deal breaker. That metal is actually Canadian pennies, 1978-1996 issue. After '96 the mint started using an alloy that was mostly zinc instead of copper.

FWIW, one CAN make a harder alloy using zinc. If I recall correctly, a fellow can get up to 1% zinc to stay suspended in his alloy. The biggest problem is the zinc does cause problems in a bottom pour pot. It isn't so much a problem using a ladle. I don't see any benefit except adding hardness. YMMV.

Edd

[I'll Make Mine]

If I recall correctly, a fellow can get up to 1% zinc to stay suspended in his alloy.

Pure lead will dissolve up to about 2% zinc without problems; it will raise the melting temperature slightly and harden the alloy, but will work like any other alloying agent. If there are other metals already present, the amount of zinc that will dissolve may be lower. There's a simple way to be sure the zinc is dissolving (alloying) rather than just melting and physically mixing (and then separating due to differing density): keep the pot below the melting point of zinc (787º F). That will ensure that any zinc that doesn't dissolve will remain solid and float on the melt, where you can skim it out.

It's important to remember that dissolved zinc isn't a problem at all; the reason zinc causes problems in a melt is that, due to the low solubility in lead and lead alloys, the zinc separates, making for hard spots, out of balance boolits, sticking (as in soldering!) in aluminum molds, and boolits with more or less zinc (hence lighter or heavier boolits) depending how much of the separating zinc is in a given ladle (bottom pour does this a little differently, but same problem over the life of a pot full).

[popper]

zinc separates, making for hard spots Same with copper I think. US pennies are Zn also?

[I'll Make Mine]

Same with copper I think. US pennies are Zn also?

The big difference between copper and zinc in this respect is that we'll never get our pots hot enough to melt undissolved copper (melting point 1984º F) or even the various tin- and zinc-free alloys, so we'll never get molten copper separating from our lead. Cartridge brass melts at around 1600º F, and gilding metal (jacket alloy) even higher. So, the only way we'll get copper into our casting alloys is by solution; the simplest method for that is to dissolve in an alloy containing the desired copper, but has a melting point not too far above that of the parent lead alloy (which is where copper babbit comes in).

And yes, US cents are about 99% zinc by weight, the remainder being the copper plating.