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Posted: Wed Feb 13, 2008 8:20 pm
by mtngun
from the old forum:

Experiments with fluxes, for ladling.

Powdered Charcoal I use a food processor to grind bar-b-q charcoal into flour. The finer, the better. About one tablespoon per 10 pounds of lead. It works OK, no smoke, and only a little bar-b-que odor. It would be the perfect flux except it takes a lot of lead out with the dross. For this reason I will only use it for wheelweight but not for expensive or hard-to-find alloys (the lead used for testing molds gets recycled over and over so the flux loss adds up over time. For normal use the flux loss would not matter much since you would only need to flux once per pot). Note: the food processor was eventually destroyed while grinding charcoal, so that was the end of the powdered charcoal flux.

Olive or canola oil Dispense with a pump bottle like used for hand soaps. About one teaspoon per 10 pounds lead. It fluxes very well with minimum waste. It does smoke, but the smoke and smell are not as bad as other waxy or oily fluxes. It does not catch fire unless the pot temperature is very high. Works better in combination with fine sawdust.

Cornmeal the most effective flux I have tried. Very aggressive. This would be good for smelting wheelweight outdoors. However, the smell is very strong.

Potato Flakes OK but not as good as cornmeal and even stinkier. Burnt potato -- yuk! :x

Fine Sawdust not so great by itself but when good when combined with olive oil or beeswax. Some woods like oak will have a pungent odor. Do not use dust from particle board or OSB because the binders may be toxic.

LBT bullet lube is a pretty decent flux, with a pleasant smell. That is the only use I have for LBT lube.

Borax seems to work at first but takes a lot of good lead out with the dross. I think Borax is an oxidizer and actually oxidizes good lead. It does not smoke or stink much and it does get the pot clean, but the loss is unacceptable.

Beeswax works well at low temperatures, smells bad at higher temperatures. Improved by adding fine sawdust.

I have yet to find the perfect flux. They all smell bad, some are just worse than others.

Re: fluxes

Posted: Tue Feb 19, 2008 1:51 pm
by mtngun
Product review: Marvelux

Ive been using Marvelux in the shop for the past month.

The good news is that it does flux.

The bad news is that it is "lossy." Typically when I flux with Marvelux I end up scooping out about 3 heaping tablespoons of grey crud, whereas fluxing with an oil or wax would produce only about 1 heaping taplespoon of brown crud. Where are the extra 2 tablespoons coming from? I suspect that the Marvelux is oxidizing the lead.

The loss isn't a big deal on a wheelweight pot that only needs to be fluxed once an hour, but it's very wasteful on very hot pot of pure lead that has to be fluxed every 10 minutes.

The other bad news is that it is corrosive. It even corroded my stainless steel pots. Chunks of rust were falling off the side of the pot and getting into the melt. The iron ladle corroded, building up 1/4" thick in some spots, and the corrosion kept plugging up the orifice.

I would definitely not use Marvelux in an expensive RCBS or Magma pot. If you are using a cheapo pot, you might get away with it if you don't flux often.

Re: fluxes

Posted: Sat Feb 23, 2008 8:07 pm
by mtngun
OK, I've started to play with the beeswax flux. So far I have only used it on WW at 700 - 750° (the real test will be on pure lead). At WW temperatures, the amount of smoke and odor seem roughly equivalent to olive oil.

Also today I tried using bar soap. Just throw a marble size chunk of soap in the pot. The soap contains some moisture, so if you dunk it under the surface, it will bubble a little, which improves the fluxing action. It creates a pleasant laundromat aroma, and only a tiny bit of smoke at WW temperature. As with beeswax, the deciding test will be fluxing pure lead at 800 - 900°.

Re: fluxes

Posted: Sat Feb 23, 2008 8:10 pm
by mtngun
Beeswax was recommended by none other than Harry Pope, who usually knew what he was talking about. Beeswax is a very effective flux. It does smoke, but no more than olive oil. For low temperature casting, the odor is not too bad, relatively speaking. At high temperatures, such as you might use for pure lead, both the smoke and the odor become quite unpleasant. To my nose, the smell of scorched beeswax is slightly less irritating that scorched olive oil, so beeswax is currently my favorite flux by a slim margin.

Bar Soap smells nice. At 700 - 750° there is no smoke. A 900° there is only a teeny bit of smoke, and the odor is still pleasant thought quite strong. On the downside, it takes several minutes to melt. Its fluxing action is not nearly as aggressive as beeswax or olive oil. I'd say it's only 10% as effective. If you leave it in too long, it burns and forms a sticky goo that sticks to the ladle and the sides of the pot. It's best to stir and skim it off just as soon as it melts. The jury is still out on bar soap. I want to use it for a while longer before I come to a conclusion.

Flake Laundry Soap It didn't smoke, but it didn't flux either, and some of the flakes plugged up the ladle nozzle.

Brake Fluid At 900° it immediately burst into flame, but there was almost no odor. At 750° it smoked, but again there was little odor. There was also little fluxing action, and it left a burnt plastic film on the surface of the melt and on the ladle. Not recommended.

Re: fluxes

Posted: Fri Jan 01, 2016 4:10 pm
by Elkins45
I'm going to have to try the cornmeal. My current favorite is rosin: smells good, fluxes, and isn't lossy at all. The tarry stuff left behind actually forms a bit of a protective layer on the exposed walls of the pot.

Plain old vegetable shortening works pretty well, and it smells a bit like chicken frying. The cheaper hydrogenated stuff is better.

Re: fluxes

Posted: Fri Jan 01, 2016 4:31 pm
by mtngun
I haven't tried rosin, will have to give it a shot. :)

Re: fluxes

Posted: Sat Jan 09, 2016 7:33 pm
by Elkins45
I remember reading about rosin as a flux from either Dean Grinnell in the ABCs of Reloading or George Nonte in Handloading for Handgunners. It has a lot to recommend it.

I have a lifetime supply of experimental bullet lube failures that make pretty good fluxes, but rosin is still my favorite for casting in cold weather when I want to leave the garage door closed.

Re: fluxes

Posted: Sat Jan 09, 2016 9:12 pm
by mtngun
Since your suggestion I have tried rosin a couple of times. My rosin is "pine gum rosin" that I bought on ebay for an unrelated project. Anyway, I suppose that since rosin is a natural product that it varies in qualities and my rosin may not be the same as your rosin.

Nonetheless, it does work as a flux. It does smoke some but only about 1/3 as much as most other fluxes. It definitely has a strong odor, but mostly smells like a pine tree so as odors go you could do far worse. So far I like it.

Haven't tried the crisco yet. :D

Re: fluxes

Posted: Wed Jan 27, 2016 12:27 pm
by mtngun
Update on pine rosin: sometimes the initial smoke can be enough to choke on, though after a few minutes it subsides and leaves a pleasant pine odor.

I tried generic criso for the fist time today. Some smoke, but less than pine rosin and less than most other fluxes. Not much odor. So far I'm OK with it.