How, exactly, do rust treatments work? Permatex calls one of its products a "rust treatment". Some other products refer to themselves as "rust converters". PickleX 20 says, "it acts as a metal surface cleaner, rust remover, 100% rust converter, very long term rust inhibitor, pre-treatment/conversion coating and a sealer...". What exactly happens when these products come into contact with metal and/or rust? For what it's worth, I did apply PickleX 20 onto bare sheet metal truck cab after blasting it. The metal still looks great, even after sitting in my unconditioned garage for about a year. I do not know what happens when it reacts to rust, but it sure does a nice job keeping the metal rust-free while I get everything else ready to paint.
I think the converters make the rust into an inert material. It usually turns the rust black in color upon contact. I used Rustoleum's aerosol converter on several of my parts. Between 1-2 years old, and no sign of issues yet (I live in a fairly dry climate though).
Rust is ferrus oxide...ferris or ferric refers to iron and oxide is oxygen. When iron and oxygen come in contact they form ferrus oxide. To remove ferrus oxide (rust) from metal you must apply a chemical that has a stronger bond to the oxide than does the iron. This is where the term "rust convertor" originates. There are many chemicals that will do this...phosphoric acid is what is found in most while things like molasses also work given enough time. I wrote a tech article some years ago on the HAMB on electrolysis for removing rust, this works especially well for smaller parts but I have seen instances where a pool was built to hold a motorhome frame that was treated using electrolysis. Other products such as rust inhibitors usually coat the iron/steel providing a barrier between it and the source of the oxygen.
I use KYB products to treat rusted metal. Three step process; cleaner, rust convertor, sealer. Many products on the market, the trick is to find one that suits your purposes. For me that long pole in the tent is using a product that can be sanded and painted with standard automotive paints.
I've had excellent results with Rustoleum rust reformer. It is available in aerosol cans and in a wipe on liquid. It is a thin liquid that will wick and penetrate into microscopic pits, seams, etc., it is great for use inside doors, cab corners, between panels and seams, on pitted metal. It has no effect on clean metal, but forms a hard black compound when it comes in contact with iron oxide aka rust. It should not be applied heavily, just enough to wet the surface. (be sure to wear rubber gloves when working with it, it will work on the iron compounds in your skin as well as it does with rust, leaving a hard black layer on the surface of the skin that must wear off. Once it has cured (completed reacting, it doesn't harden or dry, it is not a paint or coating) for 24 hours it can be primed and painted.
This may be a dumb question, but I'm always full of those.
How big of a piece would you consider for the Rustoleum rust reformer? I'm working on my inner fenders and I started thinking about sand blasting (I would need to hire that out.) Would using the rust reformer be a valid option for something like that? Obviously sand blasting would be the best option, but if the cost is too high something like this might be an option. At some point in time, when the money is saved up. I will do body work and make the truck new. But for now, I want to drive it....I'm also kind of growing fond of the patina.
If the panel has only a light even coat of surface rust, give it a sanding with a green nylon scrub pad to remove any loose rust and give it a coat of reformer, then a coat of primer followed by a color top coat all from rattle cans. If the rust is heavy and/or flaking clean it off as much as possible with scraping and with a wire brush then reformer it. be sure to follow the application instructions carefully.