When using pewter as a tin additive?

[odinohi]

When using pewter as a tin additive how do you guys go about it? All the pewter that I have bought this year is under 20 years old. Would you consider it an average of 90% tin? If I made a 100lb batch of alloy would I use say 3lbs to get my 2%+? Thanks, Tom

[Gunslinger]

When I mix alloy I regard the pewter as pure tin and then just calculate how much I need to get 2%, and then add a little extra on top of that. I don't pay much for it, and when time comes to do a new 100-150lbs batch I've probably been to 2-3 thrift shops and have accumulated enough. I really don't know the tin percentage of pewter.

BUT, I recently had a bad experience with a pot of WWs. One guy mentioned it could be impurities from the pewter. I doubt that since I only added the pewter because the melt and I couldn't se eye to eye. Here's the thread.

http://castboolits.gunloads.com/showthread.php?t=65309

[rob45]

When using pewter, consider keeping the heat turned down low. My experience has been nothing but problems if the heat is too high.

Since there is definitely more than one "formula" for pewter, and we don't know which one we have, I like to consider it as all tin when using it to sweeten WW. Same thing applies when using tin babbit. If I don't know the exact content, then I just merely regard it as a rich source of tin that's primarily used to sweeten the pot.

Don't forget to keep the heat down. I do not know why this is so; I just know that pewter likes a lower temp and gives me headaches when it gets too hot.:eek: