Treating the rust at its core is the only way to prevent it from eating away at more and more of your car. Rust is a chemical reaction, so there is no stopping it in its tracks until you address the core elements that cause that reaction. Is it true that painting treats rust, and does painting over rust stop it?
No, painting over rust does not stop it. Painting over rust is a temporary fix and will eventually lead to more extensive corrosion problems as the paint breaks down. You can try to make it look better for a little while, but in the long run, you need to address the cause of the problem, or your efforts will be short-lived.
Painting over rust on cars is incredibly ineffective. It is only a good way to stop rust temporarily. It does not protect the original metal from further corrosion or remove any existing or future rust.
However, the only way to fully stop corrosion is to completely remove the rust by sanding or otherwise physically removing it. You shouldn’t paint over any rust material. With the information below, you can find out more on this topic.
- When to Use Paint on a Metal?
- Rust Prevention Using Paint
- What to Consider before Painting Rust?
When to Use Paint on a Metal?
In the event rust has already set into the metal in question, there are two options applicable:
The Rust Could Be Scrapped off First, and Then Rust Preventing Paint Applied
This is usually done indoors, on indoor materials, or in situations where colour is important. The paint is applied to the object – which has already had the rust removed from it – and then the paint prevents further rust from setting in. This type of paint can be used on doors, chairs etc… Primarily – as previously stated – on objects where the colour is considered important.
The Second Option Is the Rust Neutralizing
This option is, unlike the previous one, typically used in situations where colour is considered unimportant. An example is painting the underside of a car. Using a rust neutralizing paint also does not require the removal of the rust before use. The rust neutralizer is applied directly to the rust on the object. It then reacts with the rust to create a stable coating over the metal.
As we’ve said before, the rust neutralizer is usually used in situations where colour is not of the utmost importance, but the rust neutralizer can also be painted over.
Rust Prevention Using Paint
In using paint in Rust prevention, there are steps to be followed. The first step of which is:
Remove Existing Rust
This can be done by rubbing the metal with sandpaper or a wire brush. This works to clear as much rust as possible before painting over. The wire brush or sandpaper used leaves the metal clear of unwanted rust coating the surface of the metal.
Apply a Primer
A primer increases the chances of the paint sticking to the metal. A rust-conversion primer is your best bet. Asides holding the paint to the metal, the rust-conversion primer gives you extra protection against rust. It serves as an extra layer of protection, applied to the metal, before the paint is applied.
Apply the Paint
After all else has been done – that is, rust has been removed and the primer has been applied, it is time to paint. Paint through your desired method – a spray can or a brush and can of paint. A rust specific paint would be best for this endeavour. Think of it as more protection against rust.
Apply coats of paint as desired or as the paint instructions dictate. Multiple coatings to ensure the metal is well covered. You can wait for the paint to dry before applying another coat to the material. You can repeat the process as deemed necessary.
What to Consider before Painting Rust?
Consider How Much Rust You’re Dealing with
When restoring rusty metal, one needs to note how much rust has been accumulated. One needs to consider if the rust is just surface rust or if it has eaten into the metal in question. If it is surface rust, then the sandpaper or wire brush treatment is the advised first step, followed by the other steps in restoring the metal.
In a case where the rust has eaten into the metal though, where the structure of the metal has been compromised, and the metal is probably now bendable in the hands or is brittle, replacing the material is probably the best course of action. Painting over might stop more rust, but the damage has likely already been done.
Metal with surface rust which can be scrapped off is ideal for a restoration.
Even if a Primer Is Used, It Is Usually Best to Remove Loose Rust before Application
Despite the primer’s ability to help paint adhere to rusty surfaces, the loose rust underneath can keep pushing up and eventually break the paint. This will let oxygen back in onto the metal and render the painting largely ineffective.
A wire brush or sandpaper will do the trick quite nicely. Running one over the metal will get rid of any loose rust before the primer and then the paint is applied.
Primers And Paint Adhesion
As has been mentioned, the use of a primer will help the paint adhere to the surface, and this will greatly help in preventing rust from developing on the metal.
If painting over extensive rust, prime it with a water or oil-based interior-exterior rust-conversion metal primer. This will convert the rust into a flat, non-rustable surface ready to be painted.
But if painting over lightly rusted or bare metal, then a water or oil-based interior-exterior rust preventative metal primer is the go-to.
You can save money otherwise spent replacing metal materials if they are painted and well taken care of beforehand. If preventative steps are taken to prevent rust, they wouldn’t become a problem later.
You can also save money restoring metal pieces instead of replacing them. As long as their condition has not deteriorated badly, following the steps above to prime and paint the material is always a good call.