Home passivation of stainless?

The wire brush embedded iron in the surface of the stainless.

I use a commercial citric acid paste for passivation. It is sold by Stellar Solutions

You can use food grade citric acid powder, but it won't be as aggressive.

The trick is to add electricity. You need about 4 amps of 24 volts DC.

You could try just using Naval Jelly from the hardware store. It is a phosphoric acid gel.

For future reference: there are several compounds made for cleaning guns that do a fine job of carbon removal. One such that is particularly good for carbon on stainless is

Note:-

Have the pan positive, you're trying to remove the iron, leave the chrome and oxidise that chrome

Mark Rand RTFM

What is safe to use as the negative electrode? Bare copper (easiest, but will it contaminate the solution)? Iron? Sacrificial stainless? Carbon rod?

Dave

You can electroclean with a conductive wand wrapped on the working end with an absorbent non-conductive material like fiberglass cloth or scotch-brite. Battery acid (sulfuric) will work for the electrolyte. Copper tube or pipe works well as the wand - if you get the polarity wrong the copper will plate on to the stainless. I used to use this method occasionally for cleaning welds on SS hardware that weren't accessible for mechanical polishing.

Mechanical polishing would also work to fix your pan.

I suspect that the problem is a result of using a carbon steel brush on the stainless. This will have embeded small particles of steel in the surface, and these rust at every possible chance. Stainless steel wire brushes are availabel for the clean up of stainless welds. The passivation may or may not fix the problem.

I'd scrub it with a Scotchbrite, then boil water in it. I have been modifying a stainless steel coffee pot to percolate faster, and leaving it on the back of the wood stove to simmer a while after each change. The shiny fresh surface turns visibly duller and slightly brown.

I use 5-10% citric acid by volume in water, with constant stirring or agitation, at 150-175F, and 10 minutes up to whenever I remember to take it out (:-)) for the time. I've read 10 minutes but I figure longer is better so I probably average 2-3 hours but I have no quantitative data to say if that is overkill or not enough. In your case I'd let it simmer in the pot for at least an hour. Just add water if needed to make up for any evaporation. Unfortunately, you may just have too much steel embedded for anything short of soaking in nitric acid. Hey, maybe the alum trick will work? Try the citric acid passivation first, and if it stops the rust then great, you are done. Otherwise, get some Alum from the spice aisle at the grocery store and put just enough water in the pan to cover the areas that rust, and then a tablespoon or two of alum. Heat over very low heat until warm to the touch, and let it sit overnight. This should dissolve the plain steel, and then repeat the passivation. I used the alum trick to dissolve a small drill bit broken off in 304 stainless steel, and made a posting about it a year or more ago. Try a google search on "ijames" and "alum".

-- Regards, Carl Ijames carl dott ijames aat verizon dott net (remove nospm or make the obvious changes before replying)

The usual precautions about hexavalent Chromium if you choose an electrolytic method.... /mark

Almost anything conductive. You are effectively plating onto the negative electrode, so it isn't going to be harmed by the electrolysis, just the acid.

Mark Rand RTFM