Impurities or oxidized desirables?

[spurgon]

New smelter here. When I melt wheel weights , how can I tell what is dross or impurities that should be skimmed off and the important-to-keep constituants of the alloy such as antimony and tin?
spurgon

[454PB]

It takes a while for the tin and antimony to oxidize, so once the pot has melted to the point of a full liquid state, you can skim off the dross. A lead thermometer can be used if desired, and 650 to 700 degrees is about right. I have smelted and cast for 37 years, and have only owned a lead thermometer for one year. Your first smelting session will teach you a lot, and you'll continue to learn from there.

[grumpy one]

As a very simplistic rule of thumb, if the stuff on the surface of the melt is grey, it is probably oxides and you shouldn't be in too much of a hurry to skim it off. If it's dark or black, it's probably crud and needs to be skimmed. When you first melt WW you'll find lots of stuff on the surface - steel clips, dirt, and probably the occasional steel weight that's slipped through - maybe even zinc. The trick is to get the temperature right, because at first the stuff on the surface includes splashes of good alloy, and some oxides. However at 650*F the good alloy disappears back into the melt, and the oxides mostly break down and go into the melt as well. You notice that you are seeing blackened clips with no trace of alloy adhering to them, and the rest of the stuff looks pretty black. Start skimming off the clips and black stuff, taking care not to dip too deep and pick up good alloy. When you've skimmed off the garbage, you'll have shiny metal on the surface with just a few black spots in it. However if you run a metal scraper around the outside of the pot below metal level, and across the bottom of the pot as well, some grey powder will float up afterwards. This is the more difficult stuff to get rid of, because it tends to stick to things instead of rising to the top. You can deal with this in either of two ways. One is to flux it repeatedly, to try to agitate it enough to get it free of what it's sticking to. The other is to leave it where it is, pour a couple of ingots, skim the surface again, and continue that way. Some of the dross that was on the outside of the pot ends up on the top of the melt after the melt recedes to a lower level each time, and you need to skim it rather than pour it into the ingot mould.

Most people seem to flux the melt. I prefer - so far - not to flux. I scrape the pot and skim the dross after each two ingots. Both methods work. You'll also find that an extremely thin layer of oxide forms continuously on the top of the melt while you are pouring ingots. You'll probably prefer to get rid of this, either by fluxing (again) or skimming (again) at frequent intervals. If you don't, that oxide will go into your ingots and you'll have to go through more fluxing or skimming while you are casting bullets - you mustn't have any oxides or garbage in your melt when you are casting, or they'll form inclusions in your bullets, causing reduced accuracy.

[HeavyMetal]

Fluxing is the most important thing you can do to your alloy while casting. If your just running a blending melt than it is not quite as improtant.

The difference is one is simply seperating what you can make bullets from and what you can't(such as the steel clips) The other operation is actual casting. Here your going to want to flux often and with the right product. I've had people tell me use the old alox bullet lube? But in all honesty it never worked plus it made to damn much smoke!

A good flux to use is: Marvelux this is made specifically for lead alloys and does not smoke or smell!
Using this will promote good alloy blending and keep what little extra metals are in wheel weights from leaving the melt as dross.

I get mine from Brownell's but you may find it any place that caters to cast bullet shooters.

[NuJudge]

Tin oxide will be this beautiful golden color. If that is all you see, leave it alone.

[Springfield]

I cast quite a bit, so I melt a lot of scrap lead. I recently did 11 buckets of wheelweights. Been doing about 10 buckets a year for a few years, so here is my take on it. I have skimmed the grey sludge on top of the mix a few times, but it was heavy and seemed like a waste of lead. Everytime I put the sludge back into the pot and fluxed it good, it returned to the pot. Now I am not talking about the zinc I get. I keep the temp down to 700 or less and can catch all the zinc weights. I mean the stuff on top that looks like lead but won't melt. When I get this I make sure the lead is at 700 and them throw some sawdust on top. Been using hamster litter but will soon have some of Pat Marlins flake flux. Anyway, throw the sawdust on top, and stir it in. It should be hot enough so that it smokes a lot, and preferably will light on fire when you light it with a match or a butane bar b q starter thingie. The grey matter always returns to the pot for me and leaves a nice shiny top with just the ash left, which I scoop out. If it looks like lead, it probably is, as long as the temp isn't over 700. Works for me. Haven't had a bad batch of lead yet in over 5 years of melting this stuff down, and I have bought some mystery lead in the past, unknown ingots, boat keels, fishing weights, you name it. You do HAVE to get a temp guage or you are shooting in the dark.

[felix]

The advantage of the MOAS size pot, 24 inches across, you just can't get the lead hot enough to be worrisome. The gage is to determine how long it takes to melt 20 gallons or more of WW. Anything over an hour or two would be safe in terms of not being too hot. At least, that is the only way to determine heat in our particular situation. I guess we could try and use a thermometer, but getting physically that close to this size of pot represents major felt heat. ... felix

[Lloyd Smale]

I used to flux wws with wax before i took the clips out but figure all that rubber and crap thats in it ought to do the fluxing for a guy. So i stir the pot real well wtih the clips in it and then take the clips and dirt out and then flux once to get any left over dirt. I rarely flux while casting. I find i make better bullets if i dont. If your casting with clean ingots and running a 20 lb or smaller pot and running the whole pot in one sitting, i dont think theres enough time involved to loose any appreciable ammont of tin or antimony.

[hungryhuntergirl]

I know this sounds funny but we flux with toilet bowl seals, cheapest and you can find em anywhere and just about at anytime!!

[montana_charlie]

I know this sounds funny but we flux with toilet bowl seals,
They used to be made with beeswax, but not any more. So, there is no longer anything 'special' about them. Regular old paraffin (for canning) is about the same stuff.

But, for fluxing oxides back into the melt, wood (sticks, chips, or sawdust) is as good as any wax...and has no ability to contaminate a mould.
CM