MANTIS: The decision to invest time and money into creating a custom rod or restoring a classic is a big one. Classic cars hold their value while a new car's value begins to decrease the moment you drive it off the lot. Over the typical 60 month financing period on a new car, it will decrease in value to less than 25% of its original price. But a well done, historically significant classic or innovative, well-designed and built rod will likely hold or increase its value. That is, if it does not decay. And the biggest decay threat is rust.
In fact, your first consideration in assessing whether a vehicle is worth restoring or customizing should probably be the extent and remediation of rust, because that may turn out to be the most expensive repair you will encounter. If you do it right, it costs. If you don’t do it right, it costs even more because everything you do beyond rust repair will fail.
Rust occurs when bare metal is exposed to salts (such as is used on roads in snow climates, and which occurs in the air in coastal climates), acids (such as acid rain and rodent urine) and soil with high iron oxide content (red mud), and moisture (rain, constant high humidity, road splash, windshield and trunk gutter leaks).
Rustoleum is a great site to understand which product is best for rust removal. When your work is accomplished, check out
The Paint Guide to see which direction in paint you want to go.
Understanding rustRust is, simply put, destructive oxidation, and it weakens metal.
Oxidation is the interaction between oxygen molecules and the other substances they come in contact with. In rare cases oxidation can produce a desired effect (such as making the hard surface we call anodized aluminum or the green patina on copper) neither of which weakens the metal itself. But usually it is destructive such as in the aging of human skin — or the rusting of an automobile. In the case of the iron component in steel, oxygen creates a slow burning process, which results in the brittle brown substance we call rust.
The reason some steel is called “stainless” is because it has a thin molecularly bonded coating of another metal that does not contain free radicals (think of those as “loose cannon” electrons).
Oxidation happens at the molecular level. Oxygen causes molecules called “free radicals” to break away. In fruit, this affects the protective peel but doesn’t damage the fruit itself unless there is a break in the peel in which case the slow burning process causes brown spots and eventually spoiling.
In a car, the outermost layers of paint are constantly exposed to air and water. If the outer peel (finish) is protected by a wax or polyurethane coating, oxygen molecules in the air interact and diminish the replenishable wax surface and the actual paint is thus spared. But if oxygen is allowed to burn up the free radicals contained in the paint, the finish becomes duller and duller. Restoration then requires removing thin layers of affected paint and reapplying a new layer of protectant, whether that is a new clear coat of paint, or a protective wax or other compound.
Rust is insidious. It is a cancer ― once it gets started, it will only grow worse. It is a continuous process. It is unwise to think that it can be arrested ― it must be eliminated, then prevented. If the base metal fails, your bondo and paint and weather stripping, seals and gaskets, even mechanical parts such as brake lines, and robust appearing structural components such as the suspension, will fail. Then, at some point, you (or some other poor guy) will have to start over. On the other hand, a properly restored car may last much longer than even a brand new car bought today. How insidious is rust? A rule of thumb is the iceberg rule ― what you see is only 10% of the hidden actual. And, let’s face it, a car with rust is a pain to work on (consider the time required to use a tap and die when a nut rounds off or a bolt breaks!).
Prevention is a whole lot easier than repairOnce you have achieved a rust-free state for your vehicle, how do you keep it that way? After all, even if you have a dozen coats of lacquer, your sheet metal is still protected by a thin layer of primer and finals coats. Get the smallest break in that protective coating ― whether from a rock thrown from a truck, or a scratch from a diamond ring, a ding at just the right angle from the door of a neighboring car in a parking lot, or a pit from the odd hail storm ― and you have an entry portal for moisture. From there, it is just a matter of time before rust begins.
No matter how mundane cleaning and waxing is (some people actually enjoy it), clean and wax your car twice a month. While you’re at it, look for scratches, pin holes, sharp edge dents, anything that breaks the paint ― especially if it shows bare metal through the primer.
If you have touch-up paint, apply it to the break with a very fine brush or even a toothpick. If you lack paint, use clear touch-up, or even clear nail polish. The goal is to fill the depression, not build up the sides and thus create a texture to catch grim and hold moisture. If your car uses a clear coat, applying clear coat after the repair will look best and further “seal the wound from infection” (actually, a very apt analogy).




A RodzReader ChallengeNow that we’ve explained scientifically what you always knew intuitively, here’s your challenge: Looks at the five photos. Rust buckets. Barn finds. Hulks. Derelicts. Whatever you call them. If you were looking for a new project, which would you want to take home? There are important visual clues in each photo. We’ll tally the votes as they come in, but we’re particularly interested in your thought process.
First, we’re interested in knowing how you weight such factors as:
- How much rust there is visible?
- Does it have any rust-through holes in it?
- n what shape were the seals and gaskets that keep the elements out?
- Will the front or rear windshield be removed?
- How will you access rusted internal and hidden areas, as well as bonded or layered panels
- How are the most common sites for rust (rocker panels, fender wells, trunk, inside doors?
- Does it appear that rust has been covered by bondo, sound-deadening tar, or gravel guard, or over chronically moist areas (such as under a padded vinyl roof)? If so, it could be rusting from inside out.
- Are there signs of previous, poorly executed rust damage repair? (Repairs will take longer.)
Second, our RodzReaders will appreciate any of your tried-and-true repair techniques. What have you learned about how and when to use:
- Media blasting (high-velocity blown sand, soda, aluminum oxide, or synthetics like Star Blast)
- Chemical stripping (e.g., Mar-Hyde Tal-Strip II Aircraft Coating Remover); chemical dipping
- Electrolytic soaking
- Pneumatic and electric sanding devices (orbital, linear, random) and abrasive media.
- Hand methods, with sanding blocks, various papers, and 3M Scotch-Brite pads.
- Riveting, spot welding and bead welding or replacement sheet metal.