Sounds like a great technique. I just need to find some of that wash soda you're talking about. Ironically, I just bought a brand new battery charger this past week. It's one of those where you can switch to from 6 to 12v, has an lcd display, monitors the charge level, all that kind of stuff. I have got a shit ton of internal coin door parts that I tried the vinegar and then the rust remover technique on, both immediately turned a weird rusty bronze color after being exposed to the air again.
I got mine from Target, but Amazon has it for $5 delivered same day (at least to my address): LINK
With some parts after de-rusting, they may flash rust if you don't apply a rust preventative. I just spray it with WD-40 and let it sit for a while, then wipe the excess off. Probably better ways. This way does leave a little bit of odor.




