lead

[beefan]

New guy here, been lurking and "listening" for a while. Now I have questions.

Are lead pipe and lead sheets generally considered pure lead? Any way to determine this without some kind of chemical analysis?

The pipes are 10"--12" long and probably 2 inches OD.

Any feedback appreciated.

beefan

[standles]

Yes lead pipe are generally accepted to be pure lead. As are stick on wheel weights.

[calsite]

I started with lead shielding I believe they call it. I think it was about the same as lead sheet but usually a bit cleaner. Good soft stuff

[Newtire]

You could give it the thumbnail test against a known pure lead sample. Go to a tire store & ask for one stick on wheel weight and do an indent test with the bathroom scale. Put a given weight on a 1/4" ball bearing or a bb and see if your stuff indents the same as the weight. Should work.

[klw]

New guy here, been lurking and "listening" for a while. Now I have questions.

Are lead pipe and lead sheets generally considered pure lead? Any way to determine this without some kind of chemical analysis?

The pipes are 10"--12" long and probably 2 inches OD.

Any feedback appreciated.

beefan

It is easy to spot pure lead. All you need is a twenty pound furnace, a lead thermometer and a stop watch. Make sure that the thermometer needle is NOT dragging on the surface behind it. Melt up a batch of metal. Insert the thermometer. Turn off the heat. Record temperature reading at EXACTLY one minute intervals. Plot up the results. Exact temperatures are not important so even if your thermometer is way off it just doesn't matter. What matters is the shape of this cooling curve.

If you do a web search on cooling curves you'll find a Cambridge University set of class notes that do an excellent job of explaining this.

But essentially any chemical element, like lead, or any eutectic alloy, like linotype, will have a VERY specific cooling curve. The liquid will initially slowly cool. Then the temperature will remain constant for a considerable period. This central flat (central because it will be in the center of your cooling curve) is where the liquid is turning into a solid. Then the solid will cool slowly.

Make sure that you record temperatures after this central flat for at least 30 minutes.

Only lead and linotype will yield cooling curves like this. Absolutely nothing else will. And if the curve isn't as described then you don't have lead or linotype. These two, incidentally, have central flat temperatures that are very far appart so there is no chance of confusing the two.

When you measure the temperature do it at exactly one minute intervals. Use a 20 pound furnace. Put your nose almost on the thermometer when taking the readings to avoid parallex errors. Don't let the thermometer needle drag on the surface behind it.

Labor intensive but I've been doing this for almost 30 years. Works like a charm.

[floodgate]

Ken:

"Only lead and linotype will yield cooling curves like this."

Not quite correct; any eutectic will do this - another common one of interest to boolit casters is 61.9% tin / 38.1% lead, and the standard 60/40 solder mix will come very close. And, of course, any of these metals in pure form.

Doug

[klw]

Ken:

"Only lead and linotype will yield cooling curves like this."

Not quite correct; any eutectic will do this - another common one of interest to boolit casters is 61.9% tin / 38.1% lead, and the standard 60/40 solder mix will come very close. And, of course, any of these metals in pure form.

Doug

There are very very pure elements and/or eutectics that a bullet caster might run into. I didn't remember the lead/tin one but I would argue that this isn't commonly available. 60/40 solder sure but I doubt that many people buy a lot of that stuff for bullet casting.

So lead is the only chemical element. And within the lead/tin/antimony alloys linotype is the only eutectic. And within the lead/tin systems I'll grant you 60/40 solder. But that's it.

Know the freezing point of 60/40 solder?

[fishhawk]

370 degres F

[klw]

While we are at it, I think that there is one eutectic in the Sb/Pb system at a temperature of 484 degrees. The corresponding percentages I don't remember. And there is one in the Sn/Pb system, as noted above. Linotype is the only one in the Sb/Sn/Pb system.

And the melting, or freezing, points for Sb is 1167, Sn 450 and Pb 621. I kind of doubt that a bullet caster would run into pure antimony or tin but I suppose it is possible.

Almost exactly 30 years ago I did cooling curves on 50/50 and 60/40 solder. Used a Lee four pound furnace and even then didn't have all that much metal. Both yielded cooling curves that looked like eutectics. That 50/50 solder would do that has always confused me. I tended to believe that that solder was just mislabeled.

[fishhawk]

30-70 is 491 F

[grumpy one]

While we are at it, I think that there is one eutectic in the Sb/Pb system at a temperature of 484 degrees. The corresponding percentages I don't remember. And there is one in the Sn/Pb system, as noted above. Linotype is the only one in the Sb/Sn/Pb system.


Ken, the lead/antimony eutectic is at 11.2% antimony, and as you said, melts at 484*F. However it is a messy eutectic because the solubility of antimony in lead at room temperature is limited to 0.44%, and even at the melting point is only 3.5%. Hence the eutectic in solid form is a lamellar mixture of lead/antimony and antimony.