ALT-4 How to Fix Rust Spots on a Car
When it comes to appearance, rust is perhaps a car's worst enemy. It not only gradually transforms what was once a shiny, new vehicle with a showroom shine into an unsightly piece of junk, but the very structural integrity itself will ultimately become compromised. As other contributors to this topic have pointed out, there is a big misconception about rust. Many believe they have surface rust when it fact it is corrosion that has begun underneath the finish and has now worked its way to the surface. Quite frankly, dishonest car dealerships are largely responsible for spreading this false belief.
Many factory warranties will guarantee against rust for a specified number of years and/or miles/kilometers driven, but the corrosion must be coming from the inside out to qualify. When the customer brings the car in to show the service manager, he or she will often be told that it is surface rust and therefore not covered. Translation? The dealership doesn't want to eat the repair costs! As said over and over, true surface rust is caused by accidents where paint is knocked off the car's surface and bare metal is exposed to the elements. Once moisture comes into contact with the bare metal, the process begins. Unfortunately, for most cars, the deterioration of metal begins in the opposite fashion.
Many of today's newer models fare much better in fighting off rust than they did a few years ago. Galvanized steel treated with compounds that thwart rust has become the industry standard. In addition, many cars now have a large number of plastic body parts; which of course can't rust. Finally, more drain holes have been added to modern cars to allow moisture to escape being trapped within the hardware. Nevertheless, harsh climates can still hasten the corrosion process; especially in areas where road salt is used several months out of the year. Frequent washing will help in minimizing this problem.
Obviously, older cars will have a greater tendency to begin rusting, so how does one go about repairing the damage? The fact that most rust will begin underneath a painted surface and not show itself until it begins to bubble through presents a major problem. The do-it-yourselfer as well as the body shop professional have to guess where it originates! The rust bubble you see may be only a fraction of an inch or a few centimeters in diameter, but the affected area could easily be ten or more times that size. It's a shame that some sort of "Rust X=Ray" device hasn't been invented to detect hidden corrosion, but it hasn't. Until then, the person doing the repair must grind away paint and metal until no more rust is seen. If it is not completely removed, it will return, just as cancer will in a person's body. As previously mentioned, in theory a rust spot that appears to be the size of a pea could end up covering an area the size of a bottle of soda-pop. Hence, the bigger the job, the more difficult it becomes to execute a flawless repair. Unless you are an expert at body repair, it is oftentimes far easier to simply replace the entire panel. By doing this, you are ensured that it is factory-fresh and as new. This has become the chosen method for the vast majority of body shops.
If you truly have mere surface rust, it simply becomes a matter of removing all traces of corrosion from the affected area, priming it, and then painting it. Spot-painting; however, is quite difficult to accomplish. It takes a special skill to blend the repaired area in with the rest of the factory finish. In such cases, most body shops will simply refinish the entire panel; such as a door, a hood, or fender. If you are not the do-it-yourself type, this is why a tiny speck of rust can cost a week's pay to fix.
In the long run, it is well worth it to stay on top of rust. When a car is well-maintained; both in appearance and good mechanical condition, it has the potential to last for many, many years. It certainly beats making monthly payments.
