I want treat some rusty metal prior to paint. I have Phosphoric acid. Can I add zinc oxide to the acid solution to create zinc phosphate that can be applied to the surface to improve the bond to primer?? Both ingredients are locally available but a prepared zinc phosphate treatment will take a lot of shipping.
Carefully shake the liquid and, holding the bottle 90 degrees to the glass slab, dispense six drops in the center of the slab. Mix each of the six portions of the powder in one at a time; after these have been added, the mixture should produce about a 1 inch “string” when stretching the mixture up with a spatula.