I gave this a go today on a set of rims that have been painted gold. I want to repaint them but have the natural alloy finish on the rim lip section.
From this:
To this:
Using this hi-tech setup:
Quite happy with the result even though its quite messy. Cost me about 15-20mins a wheels and 1kg of Bi-Carb ($3.80ish) per wheel. Still working on best method of delivery, tried straight out of box first, then out of a bottle. It needs constant jiggling to stop it blocking at suction end and to keep it sucking the soda but will try without brass fitting in the hose next time.
Rhys