This is good stuff! I have been using it for years.
It is not a solvent cleaner though so my advice is to clean your parts well first then put them in the evapo-rust. You can kind of do the same with vinegar but what ever chemical combination they use it doesn't smell like vinegar or leave any stain when it's done. There is a video somewhere where someone took this stuff with a small pump and used it to continually bath part of a frame until all the rust was gone. They setup a pan below the frame to catch the water and then recycle it back to the top portion. As long as you keep evapo-rust on a part it will over a few hours remove the rust.
The creative solution I did was removing the rust from those "under" sill plates. I used a construction cone upside down, filled it up with evapo-rust then slid the under plates in it to soak for a few hours, then flipped them to soak the other side. I maybe spent 5 minutes getting things setup, vs sand blasting or grinding away the rust possibly damaging the thin metal at the same time. Great stuff!
