Copper Contamination

[oneokie]

Have used the search function and came up without an answer.

How much copper contamination would result from placing a piece of copper tubing in the melting pot for say 30 minutes per casting session?

[Bigjohn]

I can not answer this question but pose an additional part to the question; "Copperised" lead roof flashing. All I can find out about this product is it contains a 'Matrix' of copper to stop the sheeting from moving under the effect of gravity.

Some sheeting I know to be "Copperised" has a frothy rust coloured deposit on the surface of the ingots when set.

Any ideas.

John.

[db2]

Well, I do not have an real answer but, looking at the melting point of 100% lead at 619*F and a high alloy of zinc/copper is 1302*F. There is not an issue in my book, except for a really hot pipe. :) I do not know what the composition of copper pipe is but I would think it is over 50% copper and that would require a melting temp of over 1600*F. I know some babbit has copper in it however that is done in a foundry using a chemical reaction.

I use a 3/8 copper rod to stir my pot to flux and clean the melt. It is nice cause the lead does not stick to it but, I do not leave it in the melt because that thing gets real hot when I need to use it again.

db2

[sundog]

Felix and I have purposefully added copper babbit to alloy. Too much and it will sheet while pouring instead of run in a stream, the elasticity is gone. The suspected culprit here is that the copper freezes too early. That can make casting very difficult. Keep diluting with copperless alloy until it casts. Coppered alloy makes very good boolits. If ladle pouring the sprue will stand up high with the edge retreating off of the sprue plate.

That said, I suspect your copper stirring stick does not get hot enough to shed off any metal into the mix, or at least enough to make any difference.

[Ricochet]

I've recovered gas checks that had been in a pot of molten lead for hours, and seen no sign of any dissolution of the copper.

[Morgan Astorbilt]

Copper is not that active, and can take a lot of heat. If it couldn't, it wouldn't be the exclusive(to my knowledge), material acetylene welding and cutting torch tips are made of.

db2, Copper pipe and tubing, is, for practical purposes, pure copper. This of course, does not include brass pipe, which is alloyed with zinc, and under strongly acidic conditions, the zinc will be dissolved out, leaving brittle porous copper pipe which then leaks.

Morgan

[JSnover]

If you can't see the copper coming out of solution and freezing when you pour, you don't have too much. And if your copper tube doesn't start getting smaller, you have nothing to worry about.

[trk]

Have used the search function and came up without an answer.

How much copper contamination would result from placing a piece of copper tubing in the melting pot for say 30 minutes per casting session?

Please explain what you mean by contamination.

I use scrap lead-free solder that is tin, silver AND COPPER to mix with lead and/or WW.

Is there a problem?

[JSnover]

Please explain what you mean by contamination.

I use scrap lead-free solder that is tin, silver AND COPPER to mix with lead and/or WW.

Is there a problem?

If it's lead free solder, your copper content is less than 5%. If you mix it 20::1 the copper in your finished alloy is around .25%. Nothing to worry about there.

[runfiverun]

my understanding is that some copper is a pretty good hardening agent,
and too much is bad for casting , as was mentioned earlier