Smeltied lead scrap had hidden alloy

[deepwater]

I smelted about equal amounts of: lead pipe; lead roof flashing; stained glass window came.
I expected the mix to be soft.
When using a mechanical center punch (I do not have a hardness tester) the depression was larger/deeper than WW, but nowhere near that of pure lead.
Any ideas about what caused the noticeable hardening?

Fred

[Linstrum]

The lead channeling or splining used in stained glass windows is soldered at the joints and the solder may have been lead-free plumbing solder made with bismuth, tin, and copper, which if there is enough to make a few per cent would harden your mix.


rl897

[deepwater]

I can not rule that out, but for the total of about 75# I do not believe that the percentage of solder was that high. Your insight is something that I totally overlooked.

[randyrat]

Sometimes the lead pipe i found to be a little more hard. Plus the stained glass window alloy may have had a lot of Tin in it. I'd bet you were in the 8 to 11 BNH.

Also was it real cold outside when you melted all of this.
Just a possibility you may have cold quenched it with out even knowing it.
I have melted WWs at -10 below, the ingots turned out hard.
I'm just saying; it's a possibility that there could have been some alloy in there that quenched a little.

[lwknight]

The lead pipe usually has some antimony in it too.

[onesonek]

That, and the came can vary. The came for curved cut glass is usually pure, but I believe it can be harder for certain applications.(going from memory there??? as my brother dables in stained glass) The framing channel came is usually hard for structual strength. Options to me would be to sort out the framing channel, or just smelt it all together and see what your blend ends up at. I guess that would depend on how much there is to smelt. I would be most interested in it being consistant regardless. So if I only had 50-60#, I would smelt it all down or however it takes to get a consistant blend. Even if I had to find a bigger pot. If any more than say a 100#, or what my biggest pot will handle, then sorting it out in lots and weighing may be the best option. As long as I can repeat the smelt,,, again I look for some degree of consistency.

[Charlie Two Tracks]

I melted down some lead pipe that had joints in it. Those joints are a lot harder than the pipe. At least it was in mine.

[geargnasher]

+1 CTT and others about lead pipe being harder than pure, I think it has a little antimony in it, too, but it doesn't show up in the original pipe before smelting because the pipe wasn't "water quenched" when it was made. The solder joints are usually high-tin solder, since it has a much lower melting point than the pipe. Same with most stained-glass solder, it's about 60% tin and has a much lower melting point than the "came" so when it's soldered together the process is really more like brazing steel.

Gear

[10 ga]

wheneverf I have came or pipe with joints I cut the joints out, suddenly it's 1969 and joints have a different meaning but, I smelt the joints of pipe etc... seperately and they are pretty hard and I figure at least 50% tin. Use "coin" type ingots for same and add to melt when casting until fill out is what I want. The "joints" have a much higher % of alloy stuff. I use a hatchet and when in doubt chop it out and put in "alloy" pile. 10

[Shooter6br]

Air gun pellets are more a 20-1 hardness not pure lead either (10)

[Linstrum]

Hi, 10 ga, back in 1969 I also smelt the joints, too - - - in the college dorm where I lived! But we know what you really meant!

Yeah, I figured their had to be some tin and antimony in the lead pile somewhere for it to come up a little hard. I hadn't thought about quenching from working when it is real cold out, mainly cuz it don't get that cold at the particular places where I am in New Mexico and California.


rl901

[mold maker]

I use a torch to melt most of the solder off lead pipe joints. The solder has a lower melting temp so that if your careful you can melt the solder off and leave the pipe nearly clean. It's a good way to accumulate tin to use to alloy. I too first cut the joints out of the lengths of pipe.

[Charlie Two Tracks]

Very good idea mold maker. I will try that if I ever get any more lead pipe.

[fredj338]

I am sure it's the soldered joints in the pipe or flashing. Came that I ahve gotten is pretty soft, easily bent, I doubt the hardening was from that.