I don’t know if this method is new or not, but it’s totally effective.
All you need is some of this
Aome time and some sunshine.
About an hour and a half later, this is what you get when you wash off all the toilet bowl cleaner. The edges are darker because the cleaner pooled up there.
I’ve done this on a galvanized caddy and this piece, both with good results.
I can’t wait to try this on some bigger pieces!