So I decided to work on a Roadrunner I have and decided I want to take on some issues it has with. With the exception of the quarter panels, it’s a pretty rust free car. On the interior where the headliner has split, I see some mild surface rust has started up and needs to be taken care of. The top looks fine, but the underside will. We’d attention. I am not willing to tear the car apart, so I’m looking for a one or two part brushable rust neutralizer and encapsulater. I used something long ago (maybe Silver Bullet) and wondering what people can suggest for a long term fix/protectant.

I've used Rust-Mort for some things. It's not a Por-15 type product just a thin liquid you could even spray.

ok, that would neutralize rust, but what could encapsulate it so it does not come back?

This is as good as it gets.... it is so hard it want stick to itself after 24 hrs dry time . it is an awesome rust controlling product. i am speaking from hands on use...... 1 time and forget it. https://gulfcoastpaint.com/product/mcu-100-primer-finish-moisture-cured-urethane-aluminum-coating/

Sells for about $90.00 a gallon.

For mild surface rust, simply apply by brush or spray bottle some form of phosphoric acid. Let it dry, and spray with rattle can primer or paint. Problem solved.

You could also just apply the acid and not paint it. Problem solved. The paint is just extra insurance in case the metal gets wet in the future, which could happen from condensation.

Of course, it's better to physically remove rust residues with sanding or wire brushing before applying the acid, but if this isn't done, the acid will still do a good job of killing the rust, especially mild surface rust. If brushing it on, use a nylon bristle brush or the bristles will be consumed. The reason it is better to physically remove the rust first is that the acid strength is depleted faster when rust residue is present. If the residues are not physically removed, apply additional coats of acid. Where the residue is well removed, usually only one coat of acid is needed.

Search You Tube with "removing rust with phosphoric acid " for several videos.

Many restoration shops and many collision shops use some form of phosphoric acid on all bare metal before primer, and most automotive paint stores sell it. It is a well known and common treatment in industrial applications for metal before primer, sometimes called "bonderizing". Rust Mort contains 40-60% phosphoric acid according to their safety data sheet. Other common brand names for phosphoric acid are Ospho, Rust Cure, and Gem Rust Killer, available here. Some retailers may have Gem in smaller containers than 1 gallon.

I've been using Rust Cure phosphoric acid for many decades, including today. For unseen areas like the underside of a car roof, I would apply the acid and allow it to dry. For visible areas, the acid should not be allowed to dry, as it will leave a crusty film. In this case, I allow the acid 15-30 minutes to do its job, wipe off with a rag, brush on paint thinner, wipe off, then paint after the thinner has dried. Do not rinse with water - paint thinner is better. To remove the film after the acid has dried, re-wet with acid and rinse with thinner. Never apply phosphoric acid to any zinc plated item as it is very reactive with zinc and will ruin any zinc coating. Phosphoric acid will cause discoloration to painted surfaces or epoxy-coated shop floors. Phosphoric acid will ruin your clothes. Wear nitrile gloves.

Once upon a time, after a plumber had used a metal snake in a commode, there were numerous, unsightly, dark metal markings on the bowl surface. I poured in some Rust Cure, and the bowl became spotless.

Rust Cure, Gem, and other similar forms of phosphoric acid are typically green colored. Phosphoric acid is much safer to handle than hydrochloric, nitric, or sulfuric - getting it on your skin does pretty much nothing, but if it itches, just wash it off. Soft drinks contain phosphoric acid. But if applying with a spray bottle overhead, you certainly don't want to inhale it.

It seems that every time this topic comes up, it breaks down into two main categories, rust encapsulators and rust converters. I'm not sure which is better but after reading numerous horror stories about POR-15 I lean towards the rust converters. But that is my opinion only.

I like SEM rust seal. You don't have to neutralize it after apply it like SEM Rust Mort. rust mort you need to wash it off with water to get any acid on the surface before applying anything on top of it. rust seal is good to go.

I used Corroless from Eastwood on a 69 Dart survivor car that had surface rust in the trunk seams in 1992 and when I sold it there was no further rust and it remained exactly as I brushed it on 16 years later....

Apparently Eastwood doesn't offer Corroless any longer. From another forum "It's no longer called Corroless. They now call it Rust Encapsulator. It is a fish oil product & works great. Proven better than POR-15 on rust."

yep.. 22.50 per ot.. cheaper than por and 5,000 times better . 1 coat 1 time and its awesome for this purpose

Nice👍

approximately how much would a guy need to coat a trunk floor ? would a quart do it ?
TIA as always !

thanks for the info again.

this is all true.. just one thing ,phosporic acid converts iron oxide into iron Phosphate . be sure that any product used has a chromate additive in it for corrosion control.. .ospho has it...

That not too bad of an idea, but the problem with the acid is it has to be applied overhead as this is the inside of the roof. Even with goggles, don't want that kind of stuff dripping on me. Second thing is I plan the leave the door panels on so i would probably want to avoid anything that might be a problem for clean up or damage the panels, though they will be covered.

On second thought it was SEM rust seal.

https://www.semproducts.com/product/rust-sealtm/39308

thanks for the update.

I used the OSPHO on my inside roof.i just dampened a sponge (NOT SOAKED ) and it worked great.

I'm thinking of buying a few of these and try them out. Might be worth testing and coming back every soo often to see if anything changes with results.