Adding superhard

[brucew]

My batch of clip WW lead has a bit of stick on WW in it also and seemed a bit soft so I ordered some superhard.

My first melt was 4 lbs of my WW lead, 1/4 lb superhard and a bit of tin from lead free solder (500 grains). I ended up with what looks like a thick gray foam on top that won't mix back in (all metal was clean). I heated it for a while and fluxed it 4 times with parafin but still looks bad. Nice silver lead pours out from under it and test samples are still soft.

Any suggestions/ideas?

Bruce

[onondaga]

Alloy correctly the next time. Stick-on Wheelweight melts at a higher temp than Clip-on Wheelweight. Clip-on melts at a higher temp than Superhard. Melt the highest temp metal first, flux, then add the lower temp metals and flux in order. Turning the pot all the way up and putting three alloys in ends up with what you got pretty much every time..

Super-heating to about 750 F. , then a fiery reducing flux like motor oil and stirring may or may not correct your error from attempting to alloy in the wrong order of melting temperatures .

Gary

[lwknight]

Add 1 full ounce if tin and heat everything up to about 650-700 degrees and everything should smooth up.

[kbstenberg]

Gary why does it make a difference in what order you put the alloy elements together? I believe you just wondering why?
Kevin

[brucew]

OK L W that was my next question, can I save the mess I already made. :) Thanks, I'll give that a try.

[lwknight]

Bruce , from what I gathered from what you posted , I guessed that you were to about 5% antimony. That is just about where it will not stay in solution without tin to bind it.
With the ounce of tin added , it should blend nicely.

kbstenberg , if you melted tin first it would have to get way hotter than where it oxidizes to melt the lead. If the lead is melted then you add tin there will not be pure tin at high temperature. And mostly , things just seem to go better.

[onondaga]

Kevin, when the higher melt temp metal is is fluid, it is hot enough to melt the lower temp metal. If you try in the opposite way and put a solid high melt metal into a fluid lower melt metal, it will not be hot enough to melt the other metal unless it has been heated higher than the melt temp of the other one. This doesn't work real well and the higher temp melt metal will sit there like an ice cube in water. Or you can whip it into slush by stirring it like brucew has done and have fluid metal on the bottom and slush on top.

Heating the water will certainly melt the ice cube faster, but with metals it is really better to melt the highest melt metals first and add the lower temp ones in order. Also, if you melt the lowest temp metal first and bring it up hot enough to melt a higher temp metal, then the extra heat will promote oxidation in the lower heat metal that has been overheated. This does not make alloying easy and you end up with the problem the poster "Brucew" is here asking about.

Now , you might ask, How do I tell the melt temp differences in a group of unknown lead alloys? I do a simple test by knife cutting or shaving slivers of each metal. I place two different slivers close to each other and torch them. The one that melts first is ??? You guessed it , didn't you?

Gary

[truckjohn]

Yep.. Sounds like the Antimony in that super-hard isn't happy with something in your blend....

Was there any indication of anything amiss when you mixed the stick on wheel weights with the normal wheel weights..... or did it happen only after adding the Super hard?

Reason I ask is that this sounds suspiciously like Calcium "Poisioning" in a pot of Antimonial lead.... You didn't wash anything off with hard well water did you? Didn't get agricultural lime or cement mixed into it by mistake?

Thanks

[mold maker]

Also watch for zinc stickons. They are found in stick on weights just like clip on.

[kbstenberg]

Thank you Gary an Lwknight. My personal sticky folder is filling up fast!!
Kevin

[lwknight]

I have hed some small batches of alloy that simply would not work because of some other element that I never figured out. I just used them for weights .

[brucew]

L W I never did get that batch to blend with adding more tin so I just put it aside for now. I then made another batch up with a little less superhard but I followed Gary's advice this time with great success. Thanks Gary!

Possible some zinc snuck in there, I sure had a pile of what must have been steel WWs in that bucket. I thought they were zinc but a test with the oxy-acetylene torch showed they wouldn't melt easily.

[lwknight]

Sometimes it happens. You did it all right. And I agree that some other contamination is involved. The alloying process is totally forgiving and you just cannot ruin a batch by the order of mixing. Its just some processes work out easier than others.

Don't pull your hair out over a rogue pot of alloy. Like I said , it will make decoy weights or something useful one day.

[Wireman134]

+1 Zinc