Dross

[Cimarron Red]

I cast 4000 to 5000 bullets per year, most of them heavy .45-70 bullets (500 grain plus) of 25 to 1 lead/tin alloy. The rest of my casting is with wheel weight alloy. All bullets are dipped, none bottom poured. I skim the usual amount of dross during a casting session, but I've never tried to re-melt the dross to reclaim some of the alloy that gets skimmed. Does anyone here do this? Is it worth the effort? How do you dispose of your dross? Thanks.

[felix]

Dross goes into the next big meltdown (MOAS) as if it were just another source of lead. ... felix

[GSM]

Definitely worth if you skim heavily - recovered about 5# out of one coffee can full of skimmings.

[Cimarron Red]

So you see I'm as dumb as a lead ingot. Tailings will henceforth go back into the allloy smelt. Thanks, guys.

[montana_charlie]

If you flux with a wooden stick, you can 'reduce' the dross while you are casting.
Reduction causes it to return to it's original metallic state, and recombine with the rest of the alloy.

When I clean 'crud' off the top of my alloy, it is a fine black/brown powder...no metal in it at all.
CM

[yeahbub]

In my experience, the dross usually contains flaky pale bits and sometimes a pasty grey sludge as well as some dirt/rust/crud. The sludge is the antimony coming out of solution because of a lack of sufficient tin or a high enough temperature. The flaky pale scale is oxidized tin, apparently, with the grey sludge soon to follow as the antimony loses solubility due to tin loss if I have a "borderline" tin poor alloy. Recovered linotype is like that pretty often. To fix it, I throw in a few inches of 95/5 tin/antimony plumbing solder and flux with stearic acid (something I've almost never seen mentioned on casting websites). Stearic acid in the form I get looks like coarse pretzel salt and has a waxy feel to it. It melts and burns like parrafin and nothing sucks the oxygen out of metallic oxides and returns them to a metallic state like stearate. Once it's fluxed and stirred, dirt is the only thing floating on the alloy. I learned the stearate trick from a guy that casts pewter figurines and it works better than anything else I've tried in 20 years or so. Soap makers use it as well, so it's pretty easy to get.

Since I use a bottom pour pot, to prevent continued exposure to oxygen (air) I put a quarter to a half inch or so of clean wood ashes on top of the melt, which also helps insulate and keep temperatures steady. Sprues and rejects go right through it and they don't splash as much. Not much help for the dipper casters, though.

[felix]

I've used it several times because it is a good flux. But, I have to have the wind blowing properly to use it at all. I don't mind the stick/board burning, though, especially if it is hickory or pecan. ... felix

[mtgrs737]

How much steric acid is needed to flux a 20 lb. pot? How about a smelt once the clips are removed from a 80 lb pot?

[felix]

Until the metal becomes extremely fluid. You can usually tell that fine line when rapidly stirring. It happens pretty much all at once. Too many factors on how much of anything to make that happen. Depends on the alloy, the dirt, the flux. Sometimes it never happens, and then for the very best boolits (needed only for BR guns or 1000 yard matches with big bores) you should try and find the flux that makes that happen. Motor oil will do it sometimes as well. Marvelux almost always, but that stuff has rusting problems because of the amount of oxygen (carbon monoxide?) released. ... felix

[yeahbub]

In my Lee 20 lb pot, I'll throw in a half-tablespoon with a small chunk of parrafin which it will mix with and lengthen the dwell-time. If you use stearate by itself, it burns off fairly quickly and the parrafin will slow that down, paticularly when the alloy temp is high. Have a match handy to light off the smoke with. The amount to use seems to have more to do with the quantity of accumulated oxides than the surface area on the top of the melt, but you'll want enough to put a thin film all the way across the alloy. The stearate in contact with the oxides is what does the job. Stir while it's still liquid on the alloy and you'll have a chrome-bumper shiny melt with some dirt particles floating on it.

If I get really energetic, I'll melt stearate and parrafin 1:1 and pour it into something like a candy mold. A piece the size of a hershey's kiss would be plenty for the 20 lb pot. For any pot, it'll be a question of how much it takes to cover the melt with a film of it, hence it pays to remove as much obvious trash (steel clips, etc.) as is practical. It's neat stuff - you'll hear a frying-hissing sound and the oxides will disappear back into the alloy. A good alloy will pour like water after that.

What makes it work is that at that temperature, stearate has a powerful affinity for oxygen and will bond with oxygen more tightly than the metallic oxides can hang on to it. It "steals" the oxygen from the tin and lead oxides leaving the parent metals behind in their metallic state. Once that's accomplished it's a good thing to limit the alloy's exposure to air, because it'll begin to oxidize on the surface again right away. You'll see the alloy turn straw yellow, then blue progressing to gray and it'll get duller and duller until there's obvious crunchy stuff on top again, which are oxides. Usually the alloy is "rich" enough to not be terribly bothered by a small amount and it'll be somewhat self-limiting as long as the film isn't disturbed, but when you flip some sprues into the pot, more good alloy is exposed and more oxides accumulate. Hence, I use wood ashes to limit exposure.

There are a number of fluxing agents out there (limestone was/is used in iron smelting), but they're not all useful in the temperature range that lead alloys operate in. The best ones are those that are oxygen-hungry at lead alloy temps. I've experimented with a number of the popular ones that most folks recommend, but it turns out they're usually recommended because they were told these work by someone before them rather than through the visible results test. Some used to work but don't anymore, like candles. Years ago some candle manuacturers added stearate to the beeswax and it fluxed well. Most folks didn't know there was anything but wax in the candle and got the idea the wax is what did it, or parrafin, but there's been many a pot of lead I've stirred beeswax or parrafin into and wound up removing the oxides from the pot with the other debris without knowing that I was changing the alloy. Once I got a hardness tester, the inconsistency of my results became apparent and I commenced to look deeper into the issue. Leadex is another one that works pretty well but is pricey in comparison at $8 for 4 oz's or so, plus shipping. I can get a gallon container or more of stearate from a friend for that money and that's easily a year's supply. One that I'll NEVER use again is boric acid, which melts on the alloy, covering it with a layer of, essentially, glass, of a taffy-like consistency. Yeah, there's no alloy exposed to air with this stuff, but it will mix with dirt and adhere to the walls of the pot, leaving a thick crust around the pot at the level the lead was and it won't melt again the next time you turn the pot on. I used a chisel to try to get it off but was damaging my pot more than it was worth. Heavy sand-blasting, maybe. Better to not go there.

[mtgrs737]

Thanks for the replies! I am going to try the steric acid as flux maybe with a bit of parafin or beeswax to see how it works. I also have access to lots of hardwood saw dust for fluxing the smelter I guess you just sprinkle in on top of the melt? Do you have to stir it in. Thanks!

[floodgate]

yeahbub:

What's the correct trade or USP term for "stearate/stearic acid"; how much does it cost; and what is a good source to get it from?

floodgate

[454PB]

Use Ivory soap.

I happen to use it for showering, in the bar form, and I save the end of the bars that got used up. I normally use Marvelux, but when the weather allows some ventilation, I use the Ivory. It has a slightly acrid smoke that will burn your eyes if ventilation is reduced.

It doesn't melt as quickly as parafin or boolit lube, and takes some patience, but it does a good job.

[utk]

At least where I live, we can buy pure stearic acid candles. They are the "hardest" ones and will burn a long time. I use one such candle and dip the end into the melt. Smokes a lot so I can't do it indoors.

[montana_charlie]

Thanks for that informative post, yeahbub. I think I learned something new...and useful.
CM

[yeahbub]

No problem, mtgrs737. Glad to share. I've used various kinds of sawdust in the past and got . . . indifferent results. It was nicely aromatic, though, depending on the type of wood (felix is quite correct about the hickory, pine isn't bad, never tried pecan), and tipped me off to the efficacy of keeping a layer of wood ashes on the melt. I skim off the ashes, top up the pot and flux/stir well, replace the ashes and I'm ready to go again. Intimate contact of the fluxing agent and the oxides in question are what get the job done, so stirring is an important part, though with a flux that melts like stearate, it'll go where powdered fluxes wouldn't venture.

Floodgate, I'm not sure what the USP term might be, but on the 50 lb sacks it says "stearic acid" with some notation as to what form it's in, prilled, chips, etc.
As for cost, it gets cheap fast when you buy larger quantities, like a 50 lb sack. A friend and I were going to get into smelting recovered range lead as a side business and we found it by searching online among the soap making suppliers. Turned out we could get it right here in town. I don't remember the actual price, but remember that it would be an out-of-pocket expenditure. The parrafin we would get in 1 lb packages at a grocery store and was more per pound. As 454PB notes, it's in soap, as well as some stick deodorants. I've never used soap for fluxing (or deodorant, GACK!), and I'm not sure if the smoke is conveniently flammable. I get a feeling the perfumes might make one's eyes water if it isn't - maybe even if it is. 454PB is experienced with it, I'm sure he can tell us. It may be an outdoor-only sort of thing. No doubt candle making suppliers have it as well. I'm told stearic acid in the parrafin reduces the dripping-down-the-side character some candles have and burns clean.

Utk, it's interesting that you found a source for 100% stearate candles. Very convenient. Are they domestically produced or from somewhere else? Having already been made into something, I suppose the cost would be more than the raw product, but if only a pound or two is desired, the difference may not matter much. By the way, don't you ignite the smoke when you flux? I'll admit to losing some hair on my knuckles until I made a stirring tool with a long enough handle, but a flame I can deal with - the smoke was too much for inside the house.

[NVcurmudgeon]

This is the second dross thread in recent weeks, and I am beginning to save skimmings. As a ladle caster it is impossible to always skim without picking up a little good metal. I have a large refired bean can full now and it is HEAVY, so all dross here will be saved for the next smelting. Thanks.

[floodgate]

yeahbub:

OK, I googled "Candlemaking" found several sources, and ordered it in a 5-lb bag of powder at $7.80 + shipping (watch the shipping costs; some can run pretty high).

Thanks for the info!

floodgate

[utk]

Utk, it's interesting that you found a source for 100% stearate candles. Very convenient. Are they domestically produced or from somewhere else? Having already been made into something, I suppose the cost would be more than the raw product, but if only a pound or two is desired, the difference may not matter much. By the way, don't you ignite the smoke when you flux? I'll admit to losing some hair on my knuckles until I made a stirring tool with a long enough handle, but a flame I can deal with - the smoke was too much for inside the house.

yeahbub, I believe the trade name for stearic acid is stearine and some candles are made out of that. Not too expensive for my small use. Stearine can also be bought in pellet shape for e.g. those who wish to make their own candles.
I only use the candle when cleaning wheelweights, indoors I use marvellux. Stearine would smoke way too much in my kitchen where I cast my boolits!

As for stearate, isn't that something different from stearine? (Felix please!). I have bought sodium stearate for my Felix Lube making and that was a bit more expensive.

Urban

[felix]

Stearine = "stearate" = stearic acid = any NON-METALLIC stearate. Usually you can count on the naming convention to include a metal when talking about a metallic stearate, like sodium stearate. If no mention of a metal attachment to the name, the you can safely ASSUME straight up stearate, as in the first line of this paragraph. To be absolutely sure, without doubt, ask the vendor for one of the code numbers: Merck index, CAS number, etc. ... felix

[felix]

Doug, the USP number, if any, is an indication that pleases the FDA more than anyone else. Something with this rating would indicate that the substance is "pure" enough to eat, roll on your body, etc., depending on what the substance is. Pure enough by these folks means the chemical contains ZERO (or an ACCEPTED) amount of one or more baddies that would be bodily harmful. USP is no indication of the amount of good stuff. For example, stearates are seldom more than 60 percent as the stearate formulated in the books, but several suppliers can supply USP grade. Aldrich Chemical is one supplier I used in the past for ultra pure stuff percentage wise for various experiments not gun related. Most chemicals used as "reagent grade" will be 99 percent pure or even mo'betta. Price follows the natural curve! Nothing is 100 percent pure in this world. ... felix

[lreed]

Hello, I have at times used crushed charcoal mixed with the dross in an attemt to reduce the oxides back to the good stuff. I think some metal refineing is accomplished in this manner,not sure about tin and lead. I did get a yield of metal from the dross, but was concerned about overheating and maybe gassing off the lead, a real no-no. Any comments on this method?
Thanks; lreed

[454PB]

As 454PB notes, it's in soap, as well as some stick deodorants. I've never used soap for fluxing (or deodorant, GACK!), and I'm not sure if the smoke is conveniently flammable. I get a feeling the perfumes might make one's eyes water if it isn't - maybe even if it is. 454PB is experienced with it, I'm sure he can tell us. It may be an outdoor-only sort of thing.

The Ivory soap produces a far smaller volume of smoke than candles or boolit lube. I haven't even attempted to ignite it, but I doubt that it would. Since it melts/assimilates so slowly, with some ventilation the acrid characteristic is not a problem. I used it a few times with NO ventilation and found it made my eyes burn.

I was using it yesterday, I had my RCBS thermometer in the pot, and dropped a chunk of Ivory in at 720 degrees. The window was open, and I could see virtually no smoke. Had I done this with wax or lube, it would have self ignited.

[montana_charlie]

Use Ivory soap.
Ok...now that you guys have turned me on to stearic acid...

I did some Googling, and found out that beef fat and tallow are 'rich' sources of stearic acid. So, a guy might consider dropping some of that onto a pot of lead while hoping there was no moisture in there to cause Tinsel-bell to stop by.

I seem to remember reading that tallow contains about 20% stearic acid.
So, just for comparison, how much stearic acid is in Ivory soap?
And, how much is in the common stuff sold for candle-making?

Inquiring minds can't help but inquire...
CM

[felix]

There are some veggies that have 20 percent or more too. In fact you can specify the source for the stearate to be either from animal or veggie. Again, only about 60 percent, or in some cases about 70 percent, of a stearate can be had from either of these sources. Actually, I have no idea of how much of any stearate is in a substance marketed as a soap. I guess it depends of whether pigs were more available than soybeans, or vice versa, that week the soap was made. Just don't know, MC. The info is prolly on the net somewhere, though. ... felix

[John Boy]

... don't have any metals in the dross. Only black colored impurities that are the consistency of dirt floating on top of the melt. And the melt shines like a mirror. Using a pea size of beeswax and a dusting of sawdust that is stirred with a stainless steel spoon.

[joeb33050]

I get the pot hot and flux with old Darr lube and stir and scrape and put in the stuff from the tin can and I end up with a grey powder that's very dense. I put it in the tin can. Next time I get the pot hot and flux and......
I can pretty well keep the grey stuff from having any alloy-looking knobs mixed in, if I'm careful with the dipper.
I have never had bullet weight change after this process, suggesting to me that I ain't taking out any tin or antimony.
I have never found a way to "reduce" this grey stuff-if it is oxide/s of something.
Everything I've read in the area says that neither tin nor antimony segregate or come out of the alloy.
Yet the beat goes on, and on, and on.
It seems to me that taking some of the grey stuff, and some of the alloy from the same pot, and having them analyzed, would tell us the story.
So, we're some $$ away from knowing the truth. I'm prepared to put $20 into the pot to pay for the analysis. Anyone else in interested in putting this baby to rest?
joe brennan

[BustemAgain]

I found some stearic acid here.http://www.chemistrystore.com/stearic_acid.htm
Does anyone know if this is a reasonable price or not?

[montana_charlie]

I found that yesterday, but couldn't find out how much shipping they wanted.
Best I've found (so far) in a smallish package is
http://cgi.ebay.com/Stearic-Acid-5-lbs-Low-shipping_W0QQitemZ180146842804QQihZ008QQcategoryZ3 089QQrdZ1QQssPageNameZWD1VQQcmdZViewItem
CM

[leftiye]

M.C.,
They want about $8.95 shipping. Smallest pkg they've got is 5 lbs.. Perhaps not too totally bad. Brings the cost per lb. to over $3.00.