Cleaned empty pot today

[PWS]

Figured I'd post a quick note on how I cleaned my empty Lyman Mold Master this morning.

After doing a bunch of searches here on a method, in addition to a handful of Google searches regarding lead oxides and fluxing, I finally just filled the empty pot with a 50:50 mix of 5% cider vinegar and tap water. The solution immediately started to fizz along the pot walls and I plugged in the pot until it started a rolling boil. Then, I unplugged it and went at it with a steel wire brush (toothbrush size) and gave it a good elbow greasing but for not much more than five minutes. Then, a simple rinse and slosharound with tap water and it's about as clean as it's ever been.

Probably ran about 400lbs of alloy through it since the last good cleaning and the layer of yellow oxide on the sides was getting to be upwards of 1/8" thick in places. In addition, the Marvelux scum line at the top was bugging me too.

The vinegar solution seemed to work pretty well and a lot less dusty and fusty than a powered wire wheel. Hope this helps others looking for a way to clean their empty pots. Probably would work just fine to let the solution sit without running the temp up.

[I'll Make Mine]

The solution immediately started to fizz along the pot walls

This is a strong indication that you have/had some zinc on the inner surface of your pot; lead doesn't fizz noticeably in weak acetic acid. Also worth noting that lead acetate (which you'd form with this cleaning method) is significantly more hazardous than metallic lead because it's water soluble; if you taste anything sweet while cleaning a pot this way, you're ingesting lead acetate; immediately wash your mouth out repeatedly (preferably with salt water; the chloride will react with the lead acetate to form a much less soluble, hence less hazardous compound), without swallowing anything.

[PWS]

This is a strong indication that you have/had some zinc on the inner surface of your pot; lead doesn't fizz noticeably in weak acetic acid. Also worth noting that lead acetate (which you'd form with this cleaning method) is significantly more hazardous than metallic lead because it's water soluble; if you taste anything sweet while cleaning a pot this way, you're ingesting lead acetate; immediately wash your mouth out repeatedly (preferably with salt water; the chloride will react with the lead acetate to form a much less soluble, hence less hazardous compound), without swallowing anything.


DANG! Thanks for the info. I did do all the work outside on the driveway and didn't notice any sweetness so hopefully I avoided contamination. I used vinegar because a science page indicated that "weak organic acids" will dissolve lead oxide. It wouldn't surprise me if there was zinc in/on the pot, I have a habit of running whatever scrounge is available.

Any suggestions on a better method? Filling the pot with resinous sawdust was another thought (lots of wounded spruce trees around here) but using a liquid seemed like an easier method. All of my searches did not point to a good way of cleaning the scum from an empty pot other than a power driven wire wheel.

[I'll Make Mine]

If it got the pot clean, it worked, and vinegar will remove residual zinc (which isn't a real problem unless it exceeds about 2% of the melt -- that's its solubility limit in pure lead, might be lower or higher with tin, antimony, possibly arsenic present) better than anything close to the price. If you take reasonable precautions to control the lead acetate you produce, vinegar is probably still a reasonable and reasonably safe method of cleaning a pot (after all, a powered wire brush will throw a lot of lead particles into the air, and inhaling those is probably no better for you than trace exposure to lead acetate).

Also worth noting that even if you did ingest a little lead acetate, the amount from a single pot cleaning (and a drop or two of solution) probably isn't a big deal to worry about -- it's just something to take precautions against if you use vinegar to clean your lead pot.

[Beau Cassidy]

How hot was your pot when you did this?

[PWS]

How hot was your pot when you did this?

Basically, a few days earlier, I ran the pot empty by casting bullets, then a few 1lb ingots once the flow was too weak to fill the mold, then inverted it to recover what remaining liquid metal would come out.

The day I cleaned it, it was cold to start with and the few tablespoons of lumpy dross remained in the bottom of the pot. I then added the 50:50 mix of vinegar and water, vinegar first. That's when it fizzed the most along the pot walls - maybe a 1/8" layer of tiny bubbles.

Plugged it in and let it get just to a boil then pulled the cord mostly because it was ready to boil over. Being 20degrees outside and blowing 40mph, it didn't stay hot long! Scrubbed around in it about 5 minutes with the wire brush and poured the dirty water and bits of loosened dross into a 5 gallon pail. Sloshed about a gallon or two through it (garden hose was frozen) and that was that!

The remaining heat dried everything but I took the precaution of refilling it with ingots while out on the driveway and letting it come up to liquid then back to solid before bringing it back to the casting bench.

Thanks for the follow up, I'll Make Mine. My wife did poise that very question - what's the disadvantage of handling a contaminated liquid vs a bunch of contaminated dust? Just gotta figure out what to do with that 2 gallons of contaminated ice out there in the bucket in the driveway...

[I'll Make Mine]

When the bucket melts, try pouring in a half cup of table salt and stir it up well. You should get a fluffy precipitate of lead chloride, if there's lead acetate in the solution. Assuming that's the case, keep adding salt until you don't get any more precipitate, then filter the liquid through a paper towel in a funnel (that won't ever be used for food). The liquid will have sodium acetate and only a tiny trace of lead chloride in solution and can safely go down the drain; the precipitate and the paper should be disposed of as you do your dross (properly, via household hazardous waste channels).

[shadygrady]

send thaT zinc to me

[M Hicks]

That is some good info PWS. Thanks for sharing. I think I will have to scrub mine shortly.