I’m not entirely certain what the process involved was… the frame had sat bare for a bit as it went back for a second round of repairs… so it needed a good clean up, I think after some sanding etc it was a treatment applied to the outer of the frame where the paint is headed to make certain no contaminants were left hanging around.
I believe in the photo it’s so shiny as it was just applied, I’ll attach the only other photo I got.
For internal corrosion I can only think of the JP Weigle frame saver, but I think that’s more preventative and helps corrosion from spreading rather then battling it… I’ll be spraying some into my frame before building for sure…