Pot Scrape/Cleaning

[Rick]

From the book "From Ingot to target, page 37, chapter on fluxes. By Glen Fryxell.

http://www.lasc.us/Fryxell_Book_textonly2.pdf

Some of the commercial fluxes on the market today contain boric acid, borax, or other borate containing materials (e.g. Marvelux). These materials are fluxes in the true definition of the term since they melt to form a borate glass which entrains any oxidized materials and extracts these contaminants into the molten glass phase. These fluxes have the significant advantage of being smoke-free and odorless. They are also extremely effective at removing contaminants. This is because the borate anion binds all metal cations and extracts them into the molten borate glass. Unfortunately, this includes any oxidized tin, and so the alloy is depleted of this valuable component. The borate fluxes do nothing to reduce the oxidized tin, nor do they protect the melt from further oxidation. You’ll note that this behavior is exactly opposite to that of the waxes, described above.

 

[farmboy]

This is a new to me RCBS Pro-Melt pot. It came to me in good looking condition...empty. I cleaned it up to look almost new on the outside, but the inside is a different story. I thought the nozzle was clear but noticed there was a yellow mass down inside of it. Should have fully removed it but I didn't. Filled with clean ingots and turned it on. In 10 or 15 minutes it had melted but would not let anything out. Tried a torch on the nozzle...no help. So here I am with a half full pot of cold lead. Think this morning I will take the base off so I can get to the nozzle with a drill.

 

[Rick]

In addition to the above on marvacrap, it is also the most hydroscopic stuff I've ever seen. Will rust up everything in a heartbeat and is often the cause of bringing on the tinsel fairy.

Could well be your yellow mass is from marvacrap, it hardens like a rock and is tough to grind off the inside of the pot and the spout.

 

[Bret4207]

I wonder if Marvacrap would make decent brazing flux?

Hmm, good question. I use straight Borax, as in "20 Mule Team", on bare rod. Temps are higher with brazing I think, might work. Wonder if it would leave the crusty stuff?

 

[farmboy]

I wonder if the previous owner sold it because it was plugged up and didn't know how to fix it? The reason I quit using Marvelux was things began to get rusty. Always seemed to have water on outside of can. That was 20-25 yeas ago.

 

[Bret4207]

I'm sticking with the stick and stir/scraping. It works for me.

 

[Ian]

Hmm, good question. I use straight Borax, as in "20 Mule Team", on bare rod. Temps are higher with brazing I think, might work. Wonder if it would leave the crusty stuff?

Yup, been using 20 Mule Team for 40 years. Warm the rod, poke it through the hole in the top of the box, give it a twist, and apply to joint.

 

[Dimner]

This is a new to me RCBS Pro-Melt pot. It came to me in good looking condition...empty. I cleaned it up to look almost new on the outside, but the inside is a different story. I thought the nozzle was clear but noticed there was a yellow mass down inside of it. Should have fully removed it but I didn't. Filled with clean ingots and turned it on. In 10 or 15 minutes it had melted but would not let anything out. Tried a torch on the nozzle...no help. So here I am with a half full pot of cold lead. Think this morning I will take the base off so I can get to the nozzle with a drill.

The RCBS pro-melt is what I also use. I should have mentioned in my original post, when I emptied and fully cleaned the pot, and found gunk in the nozzle as well. I removed the whole spout stopper assembly and cleared out as much as I could from inside the pot. Using what basically can be thought of as a dental pick, an electronics sized flat head screwdriver for a scraper, and tweezers to remove gunk. Then I flipped the pot upside down to get out any other nozzle gunk that was free to fall.

After that.... I put in the clean alloy and proceeded with the process outlined in the previous post.

 

[fiver]

i know marvelux works for soldering.
it can also be used to get antimony ore into an alloy.
it's a good ant killer too if mixed with Jello.

 

[Brad]

My understanding is that Marvelux is largely boric acid. Forms a sort of glass on the surface of the melt.