When stainless isn't

[tafinaf]

I got a copper tea urn that I wanted to use as a boiler. Unfortunately it was zinc lined inside, so I made a few bucketfuls of diluted hydrochloric acid to strip the zinc. I will write up a separate post to document the process once it's over, but now to the point.

5L hydrochloric acid-based patio cleaner watered down to 30L. So you can imagine it wasn't extremely concentrated. I ended up dumping one bucket down the stainless steel kitchen sink. I figured it shouldn't hurt to clean the drains. I thought about wiping the sink dry but... it was late at night and I was too tired. Imagine my disappointment to find the sink in the morning covered with rust! It took me half an hour of hard labour to scrub it off and clean the mess.

The bottom line: stainless steel is not necessarily as durable as most people imagine. I did not take pH readings or anything as scientific and I guess that even highly diluted it was far stronger than your average wash, but (unlike the wash) it was cold and besides, this forum is supposed to be all about safety. So there.