Pot Scrape/Cleaning

[Dimner]

What do you guys use for pot scraping, especially for bottom pour pots?

I have been going back to my bottom pour pot recently and after the 3rd round of a totally filled pot, I had some very bad concentrated buildup in the lower 2 inches of the pot. And in the spout cone was a bunch of crud that was causing inclusions on nearly ever pour. A vast majority of this was the typical mustard yellowish buildup one finds in a casting pot. Not sure if that helps.

When I flux, I stir and scrape like mad with my spoon, but it seems that it's not getting any of the gunk off the wall on the lowest 2 inches, and is not reaching in between the spout stem and the wall of the pot. It's an RCBS pro melt 2. I did some searching for tips, and saw an old hacksaw blade helps, but I'm not seeing how much it will help other than getting in between the stem and the wall. Do you modify the blade at all?

Last night I spent about an hour and half draining all the lead and cleaning the walls back to the stainless steel. And working on getting all that gunk out of the spout.

So what tool do you use to scrape your walls on a half or nearly full pot as well as scrape that little concave radius intersection of the wall and the bottom of the pot?

 

[Rick]

What are you using for flux? How clean and what is your base alloy?

 

[Dimner]

When smelting from absolute raw (range scrap, other's ingots, etc), I flux twice with paraffin and once with sawdust. Then when blending an alloy into ingots that I will use for casting, I flux once with paraffin and once with sawdust. In this case, the alloy is 2.5/2.5/95 as best as I can calculate. With erring on the side of less tin that antimony. This is all done outside with smelting equipment. I feel fairly confident that my alloy is clean, but of course one man's clean is another's messy.

Then inside with the bottom pour pot, I normally only use paraffin. I tried sawdust once, did not like the extra bits I was seeing pop back up during casting. I only flux when I notice a skim of oxidization on the top of the pot.

Maybe, I should ask what is the cause for the mustard yellow powder gunk on the inside of the pot. Maybe my issue is less about scraping and more about that building up much faster than other casters seem to encounter it?

 

[Walks]

I use the back side of an old hacksaw blade.

The BACK SIDE ONLY. And I scrape when the pot is freshly emptied and still hot. Gloves and great care NOT too get burned.
I use a one inch putty knife for the bottom, remove the pouring "pin" and polish it with 0000 steel wool. Once the pot is clean and COLD, I polish the liner with 0000 steel wool.

 

[Rick]

Then inside with the bottom pour pot, I normally only use paraffin. I tried sawdust once, did not like the extra bits I was seeing pop back up during casting. I only flux when I notice a skim of oxidization on the top of the pot.

First, paraffin or any other wax is not flux and cannot "flux" the alloy. "Flux defined as "cleaning".

Second, never try to push the sawdust under the surface of the melt. Ever. While the charred sawdust is of course far lighter than lead the lead is dense enough to hold it in suspension. That is what you are seeing pop back up. To correctly flux allow the sawdust to charr on the surface and while stirring the alloy bring it up to the surface and pour back through the sawdust. Takes some time to do it right, a quick swirl won't do it.

 

[Ian]

Been using the same long stainless steel tea spoon for over 30 years. On the rare occasion I empty and clean the bottom-pours they get wiped out with a damp Scotch Brite pad and rinsed in the garage sink.

 

[Dimner]

Sounds like I need to figure out why I'm getting extra inclusions on a pot that barley has 50 lbs poured through it in its lifetime. Rather than worry about scraping.

 

[Ian]

Probably because you're screwing around with trying to clean it too much when it's full.

Or.......tossing cull bullets and sprues back into it while you're casting.

What happens when a solidified bullet goes back in the melt is it sinks straight to the bottom due to higher density than the same molten alloy, then once on the bottom it does melt except for the oxide skin (which melts at a far higher temperature) and that skin shrivels into a little clump of gak that binds with the surface tension of the metal on the bottom of the pot and migrates to the spout where it flows out and causes an inclusion in your bullet.

If you're going to recycle bullets and sprues in your bottom pour furnace as you cast, float a steel plate on top and let the scrap melt on that so the oxide skins will float on top where you can skim them off at the end if a casting session. I use a hemispherical steel pipe fence post cap with a hole drilled in the bottom because it doesn't tip easily, toss the sprues into that as I cast and the clean metal flows through the hole out the bottom and the oxides build up inside the cup. At the end of a session I drop a pill of wax into the cup to convert the oxides through reduction and salvage the dross.

 

[Dimner]

Ding ding ding.

I do just that. Dump sprues right back in about halfway through. Bad habit I guess I picked up from my ladle casting. Yeeesh, I would hate to see what the bottom of that pot looks like!

I have a spare stainless steel cat food bowl that I think will be perfect for my pot. Similar to your fence post cap.

Thanks for the tip!

 

[358156 hp]

If you're going to scrape an empty pot, consider wearing a leftover procedural mask, and consider running your shop vac with the nozzle held in the mouth of the pot to control the dust. IIRC, the white & yellow buildup may be water soluble enough to clean it out with a stainless brush and keep the dust down. I haven't had to try it for a while.

 

[Dimner]

Always a good practice to avoid the dust. One of the considerations I was thinking about when I designed my casting fume hood. My head stays out of that cabinet. I hooked up an inline duct exhaust fan that moves a bunch of air straight out of the house.

 

[Brad]

You need to stir in a manner that creates a good upflow. The lead is so dense that light particles can easily stay suspended. Bring them to the surface and they will stay there.

 

[JWFilips]

my pot scrapers : large one from an old 6 inch stainless ruler with wood handle and also a small hack saw blade scraper

 

[fiver]

yep bent over hack saw blade.
and a real long tea spoon i ground the nose flat on.

i don't clean my pots too often though, at most i scrape some gunk off the top and leave the oxides there, more are gonna come anyway so why fight it.

 

[JWFilips]

When you are scraping the bottom of the pot you can feel the gunk If you toss in a pea size hunk of bee's wax it is amazing that it actually cleans the bottom of the pot also ...the scraping gets smoother and you feel you are contacting steel not gunk...the crap floats to the top! scoop it off! just Before casting put a good size piece of bee's wax in the pot and light it on fire A solid sealing crust will form on the melt and it will keep oxidation to a minimum! this is they way I do it! Once casting I add no more lead to the pot until it is almost empty. Then I reduce what is left in the pot with bee's wax, scrape the bottom and sides well and then skim off the oxides... Then I can add more alloy and start over! The melt will be clean ( as long as your ingots are super clean)

 

[Ian]

If you're going to scrape an empty pot, consider wearing a leftover procedural mask, and consider running your shop vac with the nozzle held in the mouth of the pot to control the dust. IIRC, the white & yellow buildup may be water soluble enough to clean it out with a stainless brush and keep the dust down. I haven't had to try it for a while.

Absolutely. Dust control is why I use a DAMP Scotch-Brite pad and a rinse in a sink that never sees eating or cooking utensils. That yellow lead oxide dust is probably the most toxic substance in many of our homes and absolutely must be kept from getting airborne. No cup brush on a drill indoors without a mask, unless you just want to see those little white deposits in your X-rays....

 

[Bret4207]

Since I went to a stainless steel pot my dross and general crap in my mix has dropped by, I dunno, 75-80%? Maybe more? That's no help for those using a cast iron or carbon steel pot, but I believe pain old iron oxide was the biggest culprit I had. I've given up entirely on flaming fluxes. Yeah, the smoke and fire make you feel a little like a middle ages alchemist, but it ain't worth it- specially if you cast indoors. I scrape and mix with a dry wood stick. No need for sawdust, although it's good for an oxygen barrier/insulator on top. What trash there is floats to the top as I stir with the stick, a paint stick works fine. I don't go crazy trying to get every little bit of dross off the top either. I use a bottom/side pour ladle. If it's floating on top in the pot, it's gonna float on top of the hot ladle too.

To each their own. I don't bottom pour, maybe that makes a difference.

 

[Rick]

No wood sticks for me. That stick will charr under the surface of the melt and pieces will stay suspended.

 

[Dimner]

I think I found another clue in my excess mustard yellow lead oxide buildup. This RCBS pro melt 2 with PID has the temp sensor on the opposing side of the stainless crucible. So it's not in the melt. I have known this for a while. Even though I don't like the setup, I have learned to get along with it. I usually give it a half an hour to even out after the pot tells me its at my desired temp (in this case 720* and the alloy has reached full liquid state

I had bought a digital thermometer over the weekend because my analog was not reading correctly for when I process reclaimed lead. I decided to see what the pot said with the digital thermometer, except with the sensor in the melt.

After 30 minutes liquid and pot saying 725*, the alloy was only 665*. I waited another 20 minutes until it was actually 725*. Removed the probe and started casting. Well 25 minutes in, I'm getting small inclusions from what has to be gunk in the spout. 90% less than what I had the night before, but still I would have to cull many more than I would like. Mind you, I cleaned it absolutely spotless before starting. So this is either really dirty alloy or something else is wrong. Also I noticed my bullets starting to get past that frosty stage where driving bands are fuzzy and they look time worn, like wind and sand has been beating at it for years. (Don't know how to explain the look otherwise). It's the telltale sign that the alloy is way too hot.

In goes the digital thermometer and I'm at 780*!! I tried to get the alloy to cool. But after 30 minutes it was only down to 745* so I quit for the night. Anyway, that's what happened last night. I wonder if the extra heat has an affect on buildup and inclusions.

I'm going to take 50 lbs of my alloy and clean the snot out of it this afternoon over the turkey fryer. I'm pretty confident the alloy is clean, but I have to remove that variable. Then I'm going to use that alloy in the pot having been cleaned yet again.

If this don't work, I'll just be a ladle pourer the rest of my life.

 

[Jeff H]

my pot scrapers : large one from an old 6 inch stainless ruler with wood handle and also a small hack saw blade scraperView attachment 27804View attachment 27805

Who else could have cut that kerf so perfectly straight and gotten those pins so symmetrical?

That simple tool is a piece of working art.