This has not been mentioned here, but I have posted it from time to time:

Some people are extremely sensitive to pickle salts, which can escape form minute porosities and soldered hollow forms to give rise to a reaction, varying from a slight persistent discomfort, to redness and swelling.

If not recognised, it can give rise to accusations of poor quality. The problem is easily avoided by boiling work in a bicarbonate or soda crystal solution followed by plain water, after pickling. Dennis.