Re: [APD] Caution with lead weights -- Or - Ethyl's Nails

["Jerry Smith" <jerrytheplater at hotmail_com>]

>Date: Wed, 27 Sep 2006 22:38:00 +0100
>From: Stuart Halliday <stuart at stuarthalliday_com>
>Subject: Re: [APD] Caution with lead weights -- Or - Ethyl's Nails

>I wonder if there is some sort of test we can do to tell the difference?

I once had a pure zinc ball about 2" dia. which is used as an electroplating 
anode. I needed a bar of zinc for a wet battery demonstration at my 
children's school and tried to cast it from the anode ball. I used a propane 
torch to melt the zinc and it oxidized immediately to a white powder. I was 
able to get some zinc melted and cast but it was difficult. When I was in 
High School I melted lead sheet I bought at a junk yard which had been used 
to line a stall shower under the tiles. I was casting Scuba diving weights ( 
before Buoyancy Compensator's when I still wore a weight belt.) The lead 
didn't produce much oxide on the surface, just a slight film, not the large 
quantity of white zinc oxide. Soldering copper pipes also presented no 
problem when I used 60/40 solder. I know, we don't use that anymore. All my 
present soldering is lead free.

Simple test, but destructive: melt a sample with a torch. If it turns to a 
white powder, it is zinc. If it melts with very little oxide it is most 
likely lead.

If you wanted to calculate the density that would work too, but much more 
complicated.

By the way, Plumbus lead (Pb+2) reacts with sulphate ions (SO4-2) to produce 
insoluble lead sulfate PbSO4. I am not sure if Plumbic lead (Pb+4) does the 
same. I don't have my CRC here at home. It would have to be Pb(SO4)2 if it 
exists. If any lead did dissolve and you have any sulfate in your tank 
(Epsom salts or Potassium sulfate are two possibilities) they will react 
spontaneously and the precipitate will settle into the gravel and will no 
longer cause a problem. I use this principle to keep a tin plating bath free 
of lead contamination. Just add a little sulfuric acid and poof, all the 
lead precipitates and is filtered out.

Jerry Smith in Bloomingdale, NJ


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