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savarin
01-24-2009, 10:55 PM
just in case this has never been mentioned before.
The blue/black scale that builds up on mild steel from welding and heating can easily be removed by pickling in vinegar for a couple of hours (overnight if particularly thick) Rub the scale off with a cloth, dip in a solution of water and sodium bicarbonate to neutralise the acid, wash in clean water dry, wire brush to polish and paint.

Its very very humid where I live so once steel has been cleaned with abrasives it will rust by next day, if the parts are small enough to sit in the vinegar it only takes 30 mins and the rust can be wiped off, neutralise as above.

The steel is so clean after this that it must be painted straight away to stop it rusting again.

SirJoey
01-25-2009, 09:47 AM
Except in tight places where it won't reach, I've had good success
powering it off with a hard-wire wheel in the angle grinder.

Humid here, too, & sure enough, it'll be rusty by the next day! :eek:


http://img384.imageshack.us/img384/7131/sirjoeysigmedij1.gif

macka
01-26-2009, 05:45 PM
I use muriatic acid for some applications (get it from the pool supply section of a hardware store), but mostly either a wire wheel or a flap wheel.

savarin
01-26-2009, 06:45 PM
I use muriatic acid for some applications (get it from the pool supply section of a hardware store), but mostly either a wire wheel or a flap wheel.

Yes but vinegar is cheap and not so nasty in a spill