Paint Problem, Episode III; Revenge of the Rust
Updated: Aug 30, 2019
Rust. It happens. It’s inevitable.
You paint over it but it just keeps coming back. It just won’t quit. You try to stop it and it just shows up again, back for revenge.
That’s because painting over it, even with a rust inhibitive product, doesn’t solve the problem it just covers it up. It remains, lying in wait, under your new paint job and just keeps growing until it finally makes it way through the new coating. You must get rid of it completely before applying new paint. Depending on how bad the rust is this could mean some good cleaning, or it could mean sandblasting (if able).
Rust occurs, to put it simply, when steel comes into contact with moisture and air. It shows up typically as brown or reddish-brown blotches or streaks. Sometimes it can appear as black discoloration, for instance when steel nails are in contact with damp wood that has high amounts of tannins. At first the rust may only be in a small area just at the surface but if left untreated it can spread and begin to corrode deeper into the substrate and compromise the physical structure.
Now there are different solutions based on the degree of rust. Since most or you are likely going to be dealing primarily with surface rust that’s what we’ll be discussing. If the rust goes beyond the surface it may require sandblasting and that’s best dealt with by a professional.
Let’s talk prevention first.
Rust can’t come back for revenge if it can’t start in the first place. Make sure your surface is clean and dry. If it’s a new project that doesn’t have any paint on it or if there are areas of exposed steel due to chipped paint etc. then apply a rust inhibitive product. There are both primers and topcoats out there that have the ability to prevent rust. I prefer to use a primer first, then I can topcoat in almost whatever I want. Cloverdale Paint has rust inhibitive products available, like their Rustex primer. I’m not saying that it’s going to last forever because everything breaks down eventually, even paint, but it’s going to last you a LOT longer than if you apply your paint directly to the metal. I recommend an oil-based primer. Since rust starts by steel meeting moisture and air you’re basically inviting it to show up by putting a water based coating on metal. But there are water-based rust inhibitive products out there, I just prefer alkyd (oil).
You can also prevent rust by using galvanized products. If you have gone this route and you want to paint you’ll need to make sure that whatever you decide to put on the surface is actually going to stick. Ordinary paint will end up flaking and peeling off as it can’t adhere to galvanized surfaces. Look for products that are designed to stick. Cloverdale Paint can help you out here as well with their 05910 Bonding Primer and 05130 Stain Blocking primer.
Okay. Okay. Enough about prevention. If you’re reading this, you likely have a rust issue already and you’re looking for solutions. Most of you will likely be dealing with surface rust so that’s what we will be discussing.
Eliminating Rust. Let's do it!
You need to get rid of the rust first, or as much as possible. Start by making sure the surface is clean and dry. Yes, you know what I’m going to say. Adequate surface prep. You can use TSP or if you need something a little stronger or you’re cleaning brand new bare steel, get yourself some good personal protective equipment (gloves, eye protection, respirator, protective clothing) and a can of Xylene and do a solvent wash. Change out your rags often and do not leave thinner soaked rags in a pile. They will self combust! Please only use a solvent wash when it’s appropriate and when the surface can stand up to that type of cleaning. Strong solvents can ruin surfaces and finishes so use with caution. And make safety a priority when working with any chemical solvent. Talk to your local paint representative for complete instructions and advice.
After everything is nice and clean go to work on the rusted areas with some sandpaper, you can use an electric hand sander if you want. If you need something a little more abrasive, try a stiff bristle or steel brush. You can even bring out a scraper if need be. Make sure you are very thorough, rust will just rear its ugly head again if it’s still hanging around. Once the rust has been taken care of then apply your rust inhibitive product. Make sure you apply this evenly and don’t miss any areas. The better the quality of your paint job the more you are going to protect it from rusting again.
Rusted nails: Removing and replacing with galvanized nails is the best option but if that’s not feasible then sand the nail head back to shiny metal, countersink, and coat with a rust inhibitive product. You can go the extra mile by caulking or filling each nail to prevent moisture from getting in around the nail head.
If hand tool cleaning isn’t an option or for some reason you can’t get the rust off there are rust converting products you can use. These are typically for surface rust. As I said earlier, if it goes well beyond the surface, sandblasting may be the best option. Here at the design centre we carry Corroseal. You paint it on the rust and it chemically alters it and converts it into a black substance called magnetite. Bonus; it’s a primer as well so you can paint right over top. The surface should be properly cleaned, and rust flakes should be removed with a scraper or metal brush. You could also use this to solve your rusted nail head problem.
There you have it. Rust will no longer be returning to get its revenge. At least not for a very, very long time. Looks like you’ve won this round.
Tune in next week when we talk wrinkles.
Don’t worry you look great!