How To: Stop Rust For Good

It’s a sad but unfortunate fact of life that metal rusts. Sometimes rust is called patina like when copper turns green after decades of exposure, but for most of us it’s just plain rust and we hate it.

Sure there are some times where choosing the right fastener has a lot to do about whether you have rust or not, but sometimes, you’re stuck with what you’ve got or you want to restore some gorgeous old hardware to its original splendor.

I’ve got some tricks up my sleeve to help you stop rust and send it running for the hills. None of these tips are complicated and they can all be done with simple items from the hardware store, so let’s get to it.

If your main focus is on restoring your old hardware, read this supplemental post as well: How To Restore Old Hardware.

Start With a Clean Surface

The first thing you’ve got to do is get a clean surface by cleaning off the existing rust. For this, I use a couple things depending on how severe the rust is.

1. Light surface rust – Use 000 or 0000 steel wool and polish the surface until you’re free of rust and have a smooth surface.
2. Moderate rust – Depending where you are on the rust scale, a more aggressive steel wool like a 0, 1, 2 grade may do the trick and then finish with the 0000 to put some polish on the surface.
3. Heavy rust – If you’ve got heavy rust and pitting of the surface but things haven’t been structurally compromised and there are no missing pieces, then you can use a wire wheel on either a bench grinder or angle grinder to grind off the oxidized portions. A sanding flap wheel is another good attachment for the angle grinder to clean the surface. When you’re done, go back to the fine steel wool to polish everything smooth.

Once the surface is clean, you’ve got something you can work with.

Keeping Rust at Bay

Now that you’ve got a clean surface, you have to protect it to prevent rust. The minute iron or steel is exposed to the air, it begins to rust, so don’t polish the rust off and then let it sit overnight. It began rusting the minute you set the steel wool down.

Pre-treat with Ospho

The first thing I always do is give the metal a bath or at least a good coating of Ospho. Ospho is a product that is essentially phosphoric acid (I know it sounds scary, but it’s at almost every paint store and hardware shop). For the chemistry dorks like me, phosphoric acid turns iron oxide (rust) into iron phosphate. This is an important first step because it transforms all the rust it touches (even the microscopic rust you don’t see yet) into something inert which can be painted or coated safely.

Always wear gloves and eye protection when using Ospho. It is not something you want on your skin, so read the safety instructions before using it. If you want a more gentle option, try Coca-Cola. Sadly, it’s got the same phosphoric acid in it that not only fights rust, but also has the added benefit of causing cavities.

Now you’re ready to protect against rust. I avoid most water-based coatings because water and metal are not friends and should be separated like squabbling teenagers. Here are my favorite non water-based options.

Rust Stopping Coatings

1. Boiled Linseed Oil (BLO)

This is the old school rust stopper. Wipe a good coating on any tools or hardware and let it dry for about 24-48 hours. The oil forces water out of the surface and eventually dries to a thin soft coating. This can gum up intricate moving parts especially in heavy applications, so stick with non-moving metal pieces for the best results. Read how to work safely with BLO before you try this one.

2. Penetrol

Penetrol is not just for making oil-based paints flow smoothly. It is extremely versatile and works as a great coating for metals to keep them protected from the elements. Like BLO, it creates a soft protective layer and displaces water. It dries a bit faster than BLO and that always comes in handy. Just wipe a couple coats on and let it dry overnight or 24 hrs and you should be good to go.

3. Clear Coat Spray

I’ve used spray polyurethane, lacquer and a few others but one of my favs right now is called Rust Coat Enamel by Do-it-Best.  The Rust Coat Enamel comes in a lot of colors but I just get the clear gloss spray can and coat everything metal that will be exposed to the weather or not. For non-historically sensitive projects, it coats great and really does seem to protect against the rust. It’s a Xylene based spray paint, so no water-based materials to cause rust.

4. Oil-Based Paint

If you’re restoring something like a cast-iron clawfoot tub or something else that will be painted instead of appearing to be bare metal, then you always want to prime and paint with an oil-based enamel paint. Enamel paints dry harder than normal paints and oil-based makes sure that no water makes contact with the metal. Always give at least one coat of primer (oil-based as well) and then 2 coats of paint for maximum protection.

Whatever coating you use to protect the metal, there is some maintenance involved, especially if there are moving parts or the items are stored outside. The weather is brutal to coatings on metal, and so keeping up with a rejuvenating coat every once in a while is always a good idea to stop rust from forming.