Strange melt

[nonferrous]

I have been casting with straight Clip On WW lead and having good results. Every time I flux, all I have is a thin layer of black scum to remove, It amounts to very little.
Yesterday, I melted 10 pounds of lead ingots in the casting pot and added about 1/2 pound of Monotype to see what the results would be. The whole thing was melted at about 650 and I fluxed. I had a layer of silver slush on top about 1/4 inch thick that had to be removed.
Could it be that the Type was contaminated with Zinc? I don't think that I had it hot enough to melt the Zinc, but could Zinc go to slush at that temp?
Or, could that have been Tin and Antimony coming to the top? I removed the slush and started casting and the boolits were just fine.
Thanks

[mpmarty]

Zinc won't melt at 650f. Zinc alloyed won't float or separate so it wasn't zinc. Probably tin and antimony from the monotype I smelt my monotype at 750 to 800f and cast into ingots. I then find the monotype fluxes and alloys just fine in my casting pot at 700f and in fact seems to liquefy faster than my ww ingots. I usually drop in three ww ingots to each monotype ingot but I cast my mono ingots a bit smaller than the ww. I try for 92/2/6 lead/tin/antimony. You may want to try to resmelt the stuff you took out of the pot.

[nonferrous]

Thanks,
I am sure that I did not have enough heat to melt Zinc. The Monotype was the only change and I am sure that all I had was clip on lead.
I am going to try to smelt some Monotype and introduce it in small ingot form. Maybe it will help if it is fluxed separately and then added.
I have a tech sheet that gives Monotype a melting point of 515, I thought it would blend right in.
Thanks

[jhrosier]

When I add monotype to the mix, I have to raise the temp way up & flux to get it incorporated to the mix. Then I lower the temp to what is normal for casting.
There may be another way to do this but I have not found it.

Jack

[cajun shooter]

As has been posted, you probably skimmed off the tin and antimony. There was a post on this just last week. With mono you have to stir all this back in after fluxing or you lose the benefit of using the mono.

[sqlbullet]

This is why I like to flame the flux. If there are any included metals that I don't want to skim off, a little heat right on the top always puts them back into the melt.

Very effective if you have a lot of plastic type debris. Lead tends to stick to the melted plastic, but when you light it up, it comes back off.

[nonferrous]

That's what I was kind of afraid of so I saved the slag.
What you are saying is that even though the Monotype has a lower listed melting point, it takes more heat than normal to alloy it into the WW lead.

Sqlbullet, when you say "flame the flux", I assume that you hit the top of the mix with a propane torch?

Thanks

[cbrick]

nonferrous, if what you removed looked like silver oatmeal it was the antimony that you removed.

Antimony, even though it melts at a much lower temp in a lead alloy than the actual melting temp of antimony the lead and the tin in the alloy will melt first and the antimony last as the pot heats up. That's why the antimony was floating on top, the lead and tin where at or near liquidus temp and the antimony was not. Melting temp and liquidus temp are two different things. The antimony should be fluxed back into the melt after liquidus temp is reached.

Liquidus temp is the temp that all metals in the alloy are completely molten.

Rick

[sqlbullet]

when you say "flame the flux", I assume that you hit the top of the mix with a propane torch?

I use bees wax as a flux in the casting pot. Add a little and then put a match of lighter to it, and let it burn in place.

When I am refining lead from scrap into ingots, I use either vegetable oil (from the deep fryer) or used motor oil in concert with sawdust. Again, I add the flux, stir and then apply a match or lighter to ignite.

In both cases, they burn out, the beeswax relatively fast, the sawdust/oil after a few minutes.

[nonferrous]

Rick,
Thanks for the mini Metallurgy lesson. I really thought that was what was happening, as the float looked as nice as the melt. It seemed a shame to skim it off, but I saved it.
I was over 700 degrees and did not want to go higher as to being gun shy about Zinc and did not want to ruin 15 pounds of lead.
This goes back to what Jack and some of the other guys said. What is interesting is that when already alloyed with lead as in Clip on's, it all seems to melt uniformly.
Thanks again

[nonferrous]

Sqlbullet,
I have been fluxing with paraffin wax and a wood stick, both for smelting and casting. Up til now this has worked out pretty good. I have some Beeswax and will give it a try in the casting pot.
I really like the idea of drain oil and sawdust for smelting, I am gonna try that next time. That's really getting back to basic's.

Thanks again

[Red River Rick]

Nonferrous:

Forget the "drain oil" and go with just the sawdust. Also, seems like any petroleum products added, leave a lot of residue along the edge of the pot if not completely burned off, beeswax included.

Using dry saw dust, working it under the mix, works about the best. Yes, it still smokes, but the cleanup and skimming are much easier and the end results are a cleaner and better mixed alloy.

Check out Pat Marlin's "California Mix" , in the Vendor's list, cheap, clean and works wonders.

RRR

[sqlbullet]

RRR is right. If you don't light them up, they can leave a ring of goo in the pot.

[nonferrous]

Ok, Thanks,
I'am wide open to suggestions, most of what I have tried has worked and I have cast a lot of boolits in the last month.
One thing I learned, is that even though I use a lot fewer 148 gr WC's than 158 gr SWC's, buying the 2 cavity WC mold was a mistake. After you get used to a 6 cavity mold, using a 2 cavity is no fun and it's not just about the production.

Thanks again

[cbrick]

What is interesting is that when already alloyed with lead as in Clip on's, it all seems to melt uniformly.

In clip-on WW if your lucky the antimony percentage is 3%. With the Monotype you added the antimony is 19% divided by how much you diluted it, still a lot of antimony, that's the difference.

Rick

[nonferrous]

Rick,
I have been very satisfied with the results of casting with straight clip-on lead.
I have piled up about 250 pounds of pure from various sources and will need to alloy it with the Monotype and Linotype I have around.
I guess about 6 to 1 with Monotype and 4 to 1 with Linotype. One thing I don't have is a hardness tester. I plan to use the Ball Bearing method against a known ingot of Clip-on lead and try to get close.

Thanks, Len