Patina can be matched, and faux-tina doesn't have to be ugly. I had to replace the rear cross sill under the tailgate and fix the door bottoms, fender bottoms, and hood edges on my dad's '66. I bought a kit at Hobby Lobby that uses paint with iron particles to add real rust, and layered the paint/primer the same way the old paint was. Used a rolled up rag soaked in lacquer thinner to work through the top layer of paint without sanding, then did a very thin brown "wash coat" on top of that to help match the grungy look. The whole truck was cleared with flattened SPI Universal clear after thoroughly scuffing it to get the oxidized paint and primer off.
Before- holes in doors, hood, the rear bed sill was rotted through, and the paint looked really "dry".
Shot with brown primer, then red paint, "mopped" with a thinner soaked rag. Before spraying with the over-thinned brown wash coat.
After the wash coat.
After doing this piece I figured out to used over-thinned black paint to darken the rust spots to make them match better.
After scuffing and clearing.
