[TheForge] Pickling steel with sodium bisulfate

[Bruce Freeman]

I've been an advocate of using vinegar to pickle scale from steel.  One downside to this is that vinegar is volatile, and the smell gets bad (metallic) with steel pickling inside.

So, I finally got around to trying a sodium bisulfate pickle.  Sodium bisulfate is availabe at pool supply stores for keeping the pH of pool water neutral.  It comes as fine white crystals, packed in one- or two-quart containers.

After some experimenation, I used about 1 to 2 cups per gallon of water.  (I used a rectangular plastic storage box - available in NJ from Cost Cutters - as my vat.)  The crystals go into solution fairly easily, producing no discernable heat on dissolving.  (Strong acids produce lots of heat when mixed with water.)

Much of the scale soaked off the steel within a couple hours.  Some was more persistent, but came loose with overnight soaking.  The resulting steel was nearly charcoal gray in color.  Where it was not under the solution, the steel acquired a lovely rust patina - probably more from the humidity than anything else - but this largely sponged off.  The scale did not completely dissolve.  Much of it simply fell to the bottom of the vat.  I plan to filter this off through a cloth when I transfer the acid solution to a jug for storage.

I did this on my kitchen counter.  There was virtually no odor.  Once or twice I splashed a little solution on my hands.  I rinsed them soon after, and experienced no problems (acid burns).  I DID wear glasses, however.  I don't care to get this stuff in my eyes.