So I posed this question in the Bike mechanic forum too, but was recommended to ask it here by the SS/FG forum.

I have an old early 70's peugeot UO-8 that I am restoring, and It has some minor rust here and there on the frame.

A guy I know who restores old frames suggested that I use some oxalic acid. He had said to dissolve a bit into some warm water, soak some paper towel in it, and then wrap the paper towel around the rusted parts, let soak for a bit, and then wipe off.

Well I tried that, and while it did help remove SOME of the rust, it didn't remove that much. He said that sometimes, if it is being difficult, I could make a concetrated paste out the OA, and maybe even add some Zud or Barkeepers to it, then scrub the rust with something that won't scratch the paint.

Which is what I am planning to to next, then I have some rustoleum stops rust protective primer to put on once I have removed the rust.

The question I have is, is the paste method the optimal way to remove the tougher rust from the frame? Is there a better way?

I don't want to re-paint the whole frame, my plan was remove the rust, apply some rustoleum primer, then just do some paint touch ups, so I don't have to remove the decals.