rust- powder flux

[junker]

my mentor told me i need rust-powder mixed in with my flux to make sure there are no leech lines (those white lines along alot of forgewelds). so i went to my auto shop teacher and asked if i could clean out metal powder buildup from the brake rotor/drum cutting machine. can i just use this as is, or do i need to let it turn into rust powder?

[781]

If you use boarax in the formula and have humidity and dont etch or wash the flux off you are going to have white crud showing up eventually no matter what you add to the mix.

[Sam Thompson]

I've never heard of rust being used, many recipes (rather than just borax) contain hammer scale or iron filings. Welding works fine without flux anyway.

[pkrankow]

Scale is rust, but contains whatever impurities were in the steel being worked.

Look up some commercial fluxes, and then check the MSDS to see what they use. Most are rather transparent, only using synonyms. Very few include percentages of ingredients.

Phil

[Sam Thompson]

Rust (Fe2O3) and scale (FE3O4) are different oxides of iron.

[junker]

he's having me use a mixture of boric acid, rust powder, and a third thing that i don't know yet

[Glenn]

There is a difference between rust and iron filings (fine pieces of new metal with NO rust on them). Please be specific as to which one you are talking about and or using.

[Nakedanvil - Grant Sarver]

I think someone is blowing smoke up your ash-dump. Many recipes for flux do call for scale and some call for "iron" borings. Rust or scale shouldn't matter, they are the same at high temperature. Many do confuse "iron" and "cast iron". The old recipes were pretty clear on "iron" not cast iron. Brake drum turnings are cast iron or various modern cast alloys plus a bunch of powdered brake shoes and pads, none of which probably help welding.

[pkrankow]

You know you can always call up your pottery supply store. There is usually one in every major area, and most will ship. Iron oxides are used as pigments, and available as pure powders.

http://www.columbusclay.com/Raw_Materials.htm#I

Phil

[Wesley Chambers]

Have not noticed any lines on my welded shoes but anyway, if I'm in the gas and need the help this is where I turn~



But would rather just crank the heat in the coke!

[Sam Thompson]

I've seen 'magic powder' thrown into the fire to help welding, that seemed to contain iron filings to make sparks and create a theatrical effect for onlookers. I don't think it makes any difference to the weld.

[thecelticforge]

I have used playground sand as flux before and don't remember any white lines. Perhaps you should try it.