I have a room where I exposed a brick wall and redid the mortar by tuckpointing. It look beautiful but the whitish residue from the mortar needs to be cleaned and the best way to do it is using hydrochloric (AKA muriatic) acid. I have done that before and the results are beyond amazing. It made my 100+ yr old brick look brand new clean but with the old retro shape. One couldn't ask for more.
However, in this room, another thing that is partially exposed are spiral AC ducts, although on the other side of the room from the wall. I was concerned whether the vapors from the acid may corrode the metal ducts and whether it makes sense to wrap it in some sort of plastic sheeting.
I do plan to use a gas mask and goggles with the window open and a fan blowing out hard when I'm doing this. I know it's not recommended for indoor use but the results I got before were so awesome that I don't wanna settle for anything less.
Best Answer
Yes. I used to keep my acid in a large container along with some paint thinners and removers. Even with the acid bottle tightly sealed, the metal paint thinner containers rusted after a couple of weeks. Will enough vapors get at your ducts to rust them? Can't say, but it's worth the effort to wrap them. Sounds like your major problems will be containing the acid so it doesn't reach the floor and neutralizing it without flooding the inside.