ALT-1 How to Fix Rust Spots on a Car
How to fix rust spots on a car is dependent on just what the rusty area consists of, as looks can be deceiving. What many people refer to as surface rust may not be surface rust at all. The only time true surface rust happens is when the finish on the car is scratched or chipped to the extent bare metal is open to the elements.
More often, what appears to be surface rust to the uninitiated is severe rust that has finally worked it way through to the surface and is now visible. So, with that in mind, the first thing you need to do is identify where the rust is really coming from. Once rust starts, it increases exponentially. Think of it as bacteria. If the smallest amount of rust is left behind after your repair job, you haven't killed it and it will be back.
Give this project some careful thought before you decide to tackle it yourself. Bodywork takes time. You will have to protect your work between stages. Rain, or even overnight dampness, will start bare metal rusting again quite quickly. Think ahead and plan for this if you don't have a closed garage to work in. It should go without mention, do not try spraying paint outside if there is any wind.
If you've caught it early and the rust is just starting, remove all signs of rust by wire brushing or by using a hand grinder. You may be able to use a Dremel, or similar attachment, for a hand drill if the area is small enough. If you're using power tools you'll want to start with a heavy abrasive grit and gradually change to a lighter grit as you get down to bare metal. If you use a wire brush you will have to finish the job by sanding. Orbital sanders are great for bodywork.
Don't neglect the safety aspects. Wear safety glasses! If you are painting in an enclosed area (best way for the job, not the best for you), wear a painter's respirator. A simple dust mask will not protect your lungs from paint fumes.
Just like any paint job, preparation is everything. Don't be afraid to take off some of the surrounding area. Chances are excellent the rust has spread under the finish in areas that aren't visible. Clean the area with a household de-greasing cleaner and rinse well to remove soap residue.
Mask off the area surrounding the repair to protect it from overspray. Let it air dry thoroughly before painting. Use a sandable primer and coat the area. The primer will help fill the scratches caused by the rust removal. After sufficient drying time, lightly sand the area.
You're ready for the final coat. Factory paint can be matched at the auto parts store according to the make and model of your vehicle. Obviously, if the vehicle has been around awhile, the finish has been weathered to some extent. You won't achieve a perfect match. If you were trying to achieve absolute perfection, you should have taken it to a professional. Apply a minimum of three light coats of your finish paint, allowing full drying time in between coats.
In severe cases, which are the most likely scenario in an older vehicle, the best method for removing rust is to cut it out. There are a wide variety of tools you can use for this, depending on the thickness of the metal, how accessible it is, and your level of mechanical skill and available tools.
The most basic level is using a pair of tin snips. The opposite end of the spectrum is using cutting torches. A reciprocating saw or jigsaw may be the best tool. If the problem is severe enough to require the use of cutting torches, you need professional help or you wouldn't be reading this article. You'll have to make that judgment call.
After cutting out the offending piece of metal, you'll have to form a new piece to replace it. Make sure that you have removed all the rust. The edges around your cut need cleaned to bare metal also, using a hand grinder. Get a piece of 20-gauge sheet metal and form your replacement piece. Allow an overlap of material for attaching it.
Using a drill and a pop rivet gun, attach the new piece of metal. Use body filler mixed according to package directions and coat the patch. If the patch is large, you can get away with just coating the seams. Apply it slightly thicker than you want the end result to be because your next step is to shave it down. Do not mix too much of this stuff at one time. Once it starts to set, it's useless, throw it away and mix another batch.
The next step can be a little tricky. You want to level the filler as best you can with a shaver. You want the filler to be set but not completely hardened. It might be a good idea to practice with it a time or two on some scrap metal. Once you see the difference is the filler in different stages of set time, you'll understand what I'm talking about.
When the filler is how you want it. Lightly sand and refer back to the painting steps mentioned earlier. Fixing rust spots on your car isn't a quick and easy job, but it is possible without being a professional. If you're going to do it yourself, just make sure you are prepared to live with the results.
