I did some sorting and smelting yesterday. I have found a new supplier for free wheel weights. It's fairly small, but regular. I was surprised about the number of zinc and steel wheelweights that I found. Anyway, I learned a few things and I wanted to share with some photos.
These photos are all zinc or steel wheelweights - all but three of these WWs are ferrous. Some of this has been reported before - my observations are:
1) Zinc or steel wheelweights are perceptibly lighter
2) When you scratch a steel WW, it only removes the paint. With a Zn WW, there is minimal penetration. With Pb alloy WWs, a screwdriver will penetrate deeper.
3) Zinc or steel WWs produce a higher pitched ring when dropped on concrete. Lead WW make more of a thud
4) A couple of them are marked with a Zn - some have a Fe (steel) with a number
5) Some of the Zn and steel WWs use a different method to attach weight metal to clip. I think due to zinc or steel's higher strength, they don't always bury the end of the clip into the WW metal. This is evident on the RH column of weights in the middle picture.
6) When you squeeze them with pliers, lead alloy WWs deform easily and Zn or steel WWs do not. refer to the RH photo
I think item #6 is the most important for me. I usually do other stuff during smelting and I check on the pot every 5 min or so. I use a slow flame on my cooker and I'd rather not hang aroung and suck up the noxious fumes emanating from the cauldron.
So what I did is spend about 20 min for 50# of WWs, checking each weight to make sure it deforms when squeezed with combination pliers. I slipped the jaw to the larger setting and squeezed each WW on the wire cutting (inside) jaws of the pliers. (see RH photo) As I mentioned the lead WWs deform easily and the Zn or steel WWs do not deform at all.
I know this isn't earthshaking, but I wanted to share for those casters who haven't encountered Zn or steel WWs in the mix. This test requires a little time, but it keeps me from worrying about ruining a batch of ingots with zinc.
Obviously, is is important to remove the zinc WWs before the smelt reaches the melting point of zinc ( approx 780F).
[IMG]http://castboolits.gunloads.com/newattachment.php?f=8&poststarttime=1203898850&*** thash=32adee6e8c62462adf1a8460b5557972[/IMG]