How do I determine the alloy that I have?

[barryjyoung]

Hey folks. We all have accurate powder measures for measuring the weight of a sample, we can also fairly easily measure the specific gravity of that sample, and many of us can measure the hardness (some of us quite accurately). Is there a formula we can use with just those three bits of information that will help us determine the alloy of lead, antimony, and tin?

Thank you.

Barry Young

[Dusty Bannister]

No, there is no formula. Some have tried, but have not been successful.

Now there is a better method that is available. Some scrap metal dealers will have an xrf scanner to get a reading on the metal. Some charge, some do it as a favor. I do not have access to those yards so use the service of BNE who is a list member and provides this for members. Send him a PM to see if his situation has changed, but in the past we have been able to send a clean small spatter of the unknown alloy and enclosed a pound of lead of any type per sample, as compensation for this service. He is prompt in his replies and has been a great benefit to this forum. Dusty

[Bigslug]

Ditto on post #2 to contact BNE, with the following added notions:

If you have absolutely no idea what your alloy is made of, there's really nothing for it but to have someone like BNE scan a sample for you. If it's a three-part alloy of lead, antimony, and tin, this is going to be your only accurate option. Hardness alone will tell you very little because of how those metals can combine, harden VERY differently based on rates of cooling, harden or soften with age, etc... Testing an air-cooled ingot both when fresh and after a couple weeks of casting can tell you enough to make a shootable bullet out of it, but it's really just a SWAGging fudge at that point.

If on the other hand, you KNOW that your alloy is JUST lead and antimony (shotgun pellets or factory jacketed range scrap) or JUST lead and tin, you can probably get pretty close to figuring out the percentages from the hardness with the forum's alloy calculator spreadsheet.

[rwadley]

I've successfully used specific gravity of samples to confirm the composition of an alloy of tin, lead, and antimony.

I used this as a reference:

http://www.texas-mac.com/Measuring_and_Using_Specific_Gravities_of_Lead_All oys.html

[Dusty Bannister]

Do you use your system to confirm or determine the composition. A significant difference and not what the OP asked. There was a very nice article in Handloader Magazine, and was included in the Art of Bullet Casting. I think it has since been found to be unreliable and has fallen from use.

[rwadley]

I used it to confirm that I received Lyman #2 alloy. It worked for that. I haven't successfully used it determine an unknown alloy.

[Bazoo]

There is an article in the Art of Bullet Casting book on the subject. More math than I can do. I cant remember the details of it, nor the author. I read it though, and it seemed as though it would work provided one was inclined. That book is included in the wolfe bullet casting DVD thing. So im told, i aint ever seen the dvd as I aint got a disc drive on my laptop.

Edit. I didnt see Dusty Banisters post before I posted.

[lightman]

I'll 2nd using BNE. I usually offer him a choice of what type of lead that he wants in trade but I think he accepts any type. Also in appreciation, I send extra. This is a pretty valuable service that we are getting for less than a dollar!

[JonB_in_Glencoe]

Melt/freeze temp and witnessing the span of the slushy stage can give a caster another clue along with hardness and weight difference (is that specific gravity?) of a cast boolit from a known mold and compared to the weight of a known alloy.
BUT, I gotta ask, why do you need to know the precise mixture?