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· Registered
473 Posts
Discussion Starter · #1 ·
I finally found some pool acid after looking all over and getting some pretty weird looks. :rolleyes:

The stuff I got says Muriatic acid on the label, contains 20% Hydrocloric (41.65% by weight).

I took a sprue leftover from my last casting session and put it into a pop bottle cap full of the acid, it started to bubble some.
I left it in the acid for just a bit over 2 hours while I watched a movie.
When I checked it, it was no longer bubbling at all but had changed to a much darker color. When melted again will it turn back into shiny lead?
After a good washing in water I put it beside another sprue from the same casting session and took a picture of it, you will see it below.
The acid treated sprue is on the right.

OK, this makes me think and brings up some questions
1. Did it stop bubbling because it ate up all the zinc or because the acid was worn out? I will have to put it into a bit more acid to check.
2. Did the acid get out all the zinc or just what was on the surface?
3. Could a person melt a large batch (200+ Pounds) of contaminated lead/zinc and pour it into thin castings, just pour a bit at a time onto a concrete floor to make really thin pieces. Then soak the thin pieces in a bucket of acid to get rid of all the zinc?
4. Will the acid destroy any of the Tin/Antimony in the lead?

I think that is all my ramblings for now.

Michael Grace

· Banned
556 Posts
Always wear eye protection before dropping anything into acid. Some things may have something on them which will give the same effect as dropping water in molten lead! I have a small scar near my eye from about 22 years ago to prove this. Secondly although the acid may prove whether or not your metal has zinc in it, it won't remove it. In order to do so, i would think the metal would have to be pure powder and be put through many soakings and cleanings.

· Inactive
3,262 Posts
When it comes to separating things like tin and zinc from lead, folks who smelter metals for a living will tell you there is absolutely no way the home caster can generate enough heat or go through the processes needed to really do the job. It's expensive,complicated, and hazardous. About the only way to use the metal for bullets is to add enough pure lead to dilute the alloy.

· Registered
7,858 Posts
I can post a few observations I guess.

I've had a (believed to be) zinc contaminated lead sinker soaking in a saltwater bath for near two weeks now. It is also "dull grey" in color. Other sinker from that casting session are still "silver" in color.

I've been reading threads/posts on another board regardind using sulfer to remove zinc from lead. Some are posting positive results about that. Be real careful should you choose to pursue that method!

I don't think anything will remove zinc from lead by surface treatment unless it was remelted repeatedly so as to bring zinc to the surface again and again. Not worth the BTU's for economic reasons in my view.

I was working a new Dodge Charger today. Happened to notice that a factory installed clip-on wheel weight was marked "ZN". Pocket screwdriver test indicated it was not lead!

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