We're just welding up some stainless tubing which has a brushed finish.

There's no real need to clean up the TIG welds which are very neetly done (not by me unfortunately) but would like to get rid of the brownish oxidised (?) area around the weld and get back to a clean stainless colour. (Using a wire brush or sander damages the existing finish).

I seem to recall an earlier thread where someone said you could buy an acid which wiped on the weld would clean away this discolouration.

Does anyone have any info on this?

yep, either mechanical polishing (best option) or stainless picking acid if you cant get in with a polishing wheel.

Do a search on google for "Antox" pickling pastes.

basically hydrochloric and hydrofluoric acid mixture in paste form.

Thanks for that, I've ordered some through a company called Foster Industrial in Leicester.

John.

Look out where you apply the acid because it realy realy creates a colour difference... it creats a much lighter surrface! also clean it with a high pressure pistol!!

Normally we grind away the weld and finally we polish it... or just vibrate it..

then you cant see the union anymore and it looks like the tube is made with its 90degrees bend

wear handshoes as the acid will make your hands colour after some days incl. nails! its rubbish stuff!!

Tks

Pickling paste, as said above leaves the surface matt silver in appearance, wherever it touches. It is double skull & crossbones stuff. Avesta is the brand I've used, its a mixture of conc nitric acid & hydrofluoric acid, very toxic, great care needed in handling and washing off afterward.

what about the stuff sold on Frosts website - suposed to take out the blue colouring on exhausts?

the blue stuf isnīt stuff

its the surface metal..

if you applie the acid it will get away, but one good run and its back again..

Tks

The stainless firm I worked for used Nitric and Hydrofluoric in the acid baths, the stuff is lethal as stated above. It used to leave a white film on the surface and the blokes who worked in there never looked very healthy. Rubber gloves, glasses and a mask are recommended, the hydrofluoric is potentially lethal in any dosage.

While the weld is still hot rub it with scothbrite type of stuff.

Thats what 907 did when he tigd my exhaust up came straight off...

No good as its now cold. May still work though.

Yeah scotchbrite is the stuff to clean/polish stainless up with. You can get a block (bit like a pencil rubber), a cloth, or a wheel to put in a drill. any will do, just some require more elbow grease than the others! Happy polishing.

As I said above, clean mechanically wherever possible (I just use a buffing wheel and compound) but there will be spots that you just can't get to, in which case a toothbrush and pickling paste is the only way to do it.

I did 95% of this exhaust mechnically, but you just can't get between the pipes at the collectors with anything mechanical.



exhaust 2

applying when hot fill fasten the process...
altough saying that the damp that is created should be as toxic as you can imagine..because of the quantity..


tks