How to Get Rid of Rust on a Car

Removing Car Rust

As car owners, we do the best we can to keep our vehicles running properly and looking their best. But for those of us with older vehicles, there is one type of issue that seems to creep up far more often than the rest: rust.

Rust can kill a vehicle if left unchecked and act as a blemish for classic and daily driver cars alike. Those brown stains and paint bubbles can mean that your car could be on the way to the salvage yard if you don’t correct it in short order, especially if it penetrates all the way to the frame.

This is because rust is a chemical reaction that is caused by the interaction of oxygen with ferrous metal molecules. This happens for most cars when they are exposed to air. Another thing that can expedite the process is exposure to winter road treatments and saltwater.

Before getting started, you should choose a day that is low on wind and has at least moderate temperatures if you can’t do the rust removal work in a garage. Keep your car clean, as dry as possible, and out of the sun. The process could take a full day to complete, so if this is your everyday vehicle, maybe wait until a weekend.

​Tools and Accessories Needed

First, you need to ensure that you are going into the situation as prepared as you can be. You can change out a few things here and there with comparable items, but this is a pretty bare-bones list as far as what you will need to get the job done.

You will need the following items:

  • Rust remover compound
  • Primer
  • Colour-matching spray paint
  • Grease and wax remover
  • Touch-up paint pens
  • Sander
  • Sandpaper
  • Sanding discs
  • Protective eyewear
  • Gloves
  • Dust mask
  • Masking tape

Removing Minor Surface Rust

When dealing with minor rust issues, such as chipping on the leading edge of the hood or spots of rust on the door or roof, something like a liquid or aerosol rust remover tends to work quite well. Make sure that you mask off the area in question with masking tape or another paint-appropriate tape. Make sure that you have a few inches of protection surrounding the rust spot.

Follow the directions set forth on the rust remover. This usually means brushing or spraying it onto the rust and letting it sit for a few minutes. When that time has passed, wipe off the residue with a clean rag and always remember to wear protective gear, because rust remover is not something to mess with.

If the rust isn’t gone, give it another spray and try again until the rust is gone. If the rust remover can’t get it all, use a light grade sandpaper to get the rest of the rust off. With the rust gone, clean the spot with the wax and grease remover and let it air dry. This could take a little time, but it shouldn’t take too long.

When you’re ready to move forward, you need to spray the primer in a light-to-medium coat over the affected area and give it an hour or so to dry. You will need to do this three times to ensure that the area is sufficiently coated.

After the primer has been applied, the next step is to spray the colour base coat, using a product thinner than the primer. Because it is thinner, you might need to do five or more coats to ensure that there is complete coverage, and you’ll want to give it plenty of time to dry in between coats to protect against dripping.

When you have sufficiently covered the area, then comes the clear coat. Spray it on thoroughly and make certain to wait a couple of days (two or three) before washing the car. If you plan to get it waxed, give it at least two months, although there are body shops that will suggest waiting six months.

And just like that, your minor rust is removed.

Removing Major Rust

However, there are some vehicles that will likely be affected quite a bit more than the rest of their fellow cars. Things like entire steel bumpers being covered in rust can mean stepping up the process to remove the rust from the metal.

You’ll want to mask off the area in question. If you wind up having to sand through the paint and primer, make sure the rest of the vehicle is protected from the super-fine dust that will be created. During this process, you will absolutely want to wear a dust mask, as inhaling the dust can lead to serious respiratory issues.

This is where having a grinder with a sanding wheel comes in handy. It will help you remove as much of the surface rust as is possible, saving you time and a lot of energy compared to sanding it by hand. Always keep in mind that you should not bear down any heavier than is necessary when removing the rust this way, as doing so can remove too much undamaged metal.

If you can, avoid using the grinder, make certain to clean the area in question with the grease remover, and use a fiberglass-reinforced body filler to fill out any depressions and holes that result from digging out the rust. Allow it time to cure completely and don’t bother doing it at all if it’s below 65 degrees outside.

When the filler step is complete, sand it with a progressively finer grit of sandpaper. When this step is finished, clean the area again with the grease and wax remover before taping off the area that needs to be painted.

The process here is very similar to the outlined steps above. Use a self-etching primer and give it the allotted time necessary to dry. Spray on several coats of paint but apply them on the lighter side, and then finish it all off with a clear coat. You will also need to hold off when it comes to washing and waxing the car to ensure that your work is not unnecessarily undone.

When to Replace

While it is always preferable to keep the parts if they can be repaired, there will come a time when spots are just too rust-laden to bother repairing them. Holes through a rusted fender will require welding, and that process is both tricky and expensive.

A good rule of thumb is that if the rust damage covers more than 20% of the part, just replace the damaged piece. It will save you time and money. The key is preventative maintenance.

During the winter months, make sure that your car has multiple coats of wax on it to help it shed road grime and water quickly as well as protect the paint. Get car washes during the winter months to prevent road chemicals and snow from accumulating.

Rust is a nasty thing to see on any vehicle, regardless of whether it is a beater that gets you from point A to point B or a classic car that you have heavily invested in. It can also shorten the life of a vehicle substantially, so do what you can to keep that nasty rust at bay and away from your car.

Last Updated On: April 1, 2020.

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