I've actually done this numerous times over the years,.works very well,...just takes time. (Overnight is usually enough for most items with basic rust) The rust jumps off the part being de-rusted,..and then it attaches to the sacrificial piece. I use to use it on stainless QC,..and a few other things as well. The bubbles that come to the top and released into the atmosphere are Hydrogen,..and explosive. Is the same idea behind Hydrogen driven engine.

Jeff