B
Bob Hollinshead
On restorations, when you are done with the paintwork on the vehicle's underside or similar areas it's a good idea as a last step to spray cavity wax into all the boxed areas and seams. You can spend all the time in the world removing corrosion from the exterior areas and still have corrosion in boxed areas and seams that eventually will crawl out to haunt you if steps aren't taken to cut off the supply of oxygen. I've taken apart cars and parts that were dipped and it is the same situation especially the tight seams. Transtar makes a good coating, 3M offers rustfighter which is ok, Amsoil MP-HD is also decent, and there are others including Rustfre and cosmoline. I usually tape up the seams to keep most of the product where it needs to be. Rotate the car and let gravity fill up voids, rotate it 180* and repeat, and rotate upright and repeat. On projects that aren't going to be judged you can seal up the seams with seamsealer prior to paint and avoid the need to mask them. Wipe off the majority of any run off as you go, let the tape set overnight while the wax sets up, then final clean any excess with solvent based W&G remover or mineral spirits. The Transtar Amber Coat is good stuff and they offer a cheap kit with a small diameter 360* spray wand that gets into areas where my Walcom setup won't go. If the car isn't on a rotissery you can still jack up the sides enough to get enough angle for gravity to help move the product where it needs to go. Multiple passes with a few hours between application is best.