Sawdust flux

[Ohio Rusty]

I'm going to try this sawdust flux as I've not tried that before, and users here seem to report good results. A couple of questions .... Why does it work? Secondly, How do you get the sawdust to mix with the lead and grab the impurities before it all burns up? I have one of the cast iron ball end pouring ladles (Lyman?) with the small spout on the end I use all the time for pouring from the lead pot. Do I pack that full of sawdust and quickly stir that around in the molten lead to flux the impurities? Last question .... How many times do I do this? I've always cast pure lead for muzzleloaders and never needed to flux, just skim and stir and skim. Thanx for you help ...
Ohio Rusty

[felix]

Sawdust turns to carbon as it burns, and that loose carbon picks up the oxygen stored as oxides on the raw metal, rendering the metallic compounds back to their non-oxidized state as the oxygen combines with the carbon as hot carbon dioxide/monoxide which rises into the atmosphere. Stir the raw sawdust into the metal for this reaction to occur, and leave the burnt mess on top of the melt to help keep new oxygen from the air from going back into the pot to recombine with the newly generated raw metal. ... felix

[Glen]

Felix pretty well summed it up. Take a spoonful of sawdust and stir it in vigorously with a full pot, then leave it in place. You can scoop it off later, as you approach the bottom of the pot, if you want to.

For more discussion on this, see: http://www.lasc.us/FryxellFluxing.htm

[dk17hmr]

I use sawdust seems to work pretty good for me, I didnt know why it works but now I do thanks Felix.

I have loads of sawdust and when I go to smelt I walk out the shop and pick half a bucket up and throw it in my dutch oven and let it dry out before I start putting in lead.

[3sixbits]

I hope you have just sawdust, hard to find just wood sawdust that is not contaminated with plastic from laminates. I bring the melt just to the point of liquidus and stir in a lot of sawdust and keep stirring for a couple of minutes until well mixed and the temp comes up to full molten state and skim. I do this two times before I cast into ingots. I do not do this in my vary clean casting furnace, that is reserved for the clean ingots only I do add powdered charcoal to cover the top of the melt in my casting furnace to control the oxidation. Congratulation, you have joined the ranks of the foundries that use sawdust to clean there metal.

[4570guy]

See this article regarding sawdust as flux:

http://www.lasc.us/FryxellFluxing.htm

I've been using sawdust for more than a year now. It works great and its free.

[sundog]

I use 'already been used' sawdust - wood ash from the stove. Works okay for me. Sometimes there's small particles of charcoal that after awhile glow as an ember until used up.

[felix]

Yep, it's carbon that you are after. I can imagine that ground up charcol would work fine as well. Or, for that matter, graphite. Motor oil is fine too, except for the smoke produced. Even used motor oil from the lawn mower. ... felix

[Marlin Junky]

Cat litter isn't carbon but it works well as a oxygen barrier and is much easier to handle than carbon dust. Cat litter works well even if you use a dipper and is much less likely to get into your boolit cavities.

MJ

[dragonrider]

IMHO ain't nothing better than sawdust, being a woodworker I have all that I will ever need and then some, I use it by the handfull so that when it reduces to carbon there will be a good layer on top of the lead. Your pot will thank you profusely, it will be so much cleaner, no crap all over the sides.

[Blammer]

IF you dip from the top like I do I have a hard time leaving it there...

[cohutt]

I tried some walnut tumbling media (aka Lizard Litter) last week on a modest WW smelt and it seemed to work very well. It burst into flame and surprised me as I was stirring it in though- i recovered and stired it in some more, scraped the side and bottom of the pot till they felt smooth- the glowing embers mentioned above showed up for a minute
I haven't tried it on my casting pot yet, still just use a little candle wax but the ingots are already very clean.

[Marlin Junky]

IF you dip from the top like I do I have a hard time leaving it there...

Try plain-wrap cat litter... 100% clay with no flavor added. It's the only thing I use after the wheel-weights have been rendered into ingots in the backyard.

MJ

[dubber123]

Cohutt, funny you mention the flame thing, as I just tried the sawdust trick, and as my pot is at near eye level, the resulting fireball had my full attention for a second there! After I laughed at myself for jumping like a fool, I got it all stirred in, and it seems to work well.

[HTRN]

I'd like to point out that what they use in Commercial smelting is Sawdust, because of the reasons already stated - cheap and works well.


HTRN

[twoworms]

Don't try used cat litter... :)

I'm going to try the saw dust the next time I smelt WW out side.

Tim

[montana_charlie]

Ohio Rusty mentioned that he uses a ladle.

To my way of thinking, sawdust is a good choice for the bottom pour guy, because he can let it sit on top of his alloy while casting. A stir, or two, from time to time...and an occasional addition of sawdust...is an easy way to keep the pot fluxed, and prevent excessive oxidation.

But I believe that the 'wooden stick' works better for the ladle lad, or the dipper whipper. There is no wondering about how to get the 'flux' deep into the alloy, and the material being used is the same, both ways.
The stick is a great scraper for the pot walls and bottom, and (while it doesn't prevent oxidation like sawdust) it makes a good spatula to recombine 'scum' with the alloy. Done thoroughly, the residue you skim out is nothing but ash, with no metal being discarded.

Naturally, when you've fluxed as much as necessary the stick is laid out of the way so there's nothing to interfere with dipping.

I hope Ohio Rusty and Blammer are still reading this thread...
CM