Powder coating a frame or a whole car

A. Hi Gary,
Unfortunately, you did not include in your post the type of powder used to coat the hot-rod or the pre-treatment the coater applied prior to applying the powder. The resistance to corrosion is a two point attack, requiring a good pre-treatment and the correct choice of powder.
If galvanising is out of the question then zinc phosphate would be top of my list. The choice of powder, as the items are out of view and you wash the hot-rod after each race, my choice would be the most resistant to corrosion -- an epoxy based powder top coat. You could even specify an epoxy primer coat into the coating system.
I think you will discover that most commercial chassis and brake parts ARE powder coated but with a good pre-treatment included.

A. I have to agree with Terry. A properly prepared surface with a good powder coat should shrug off a little bad weather and salt. It sounds like you got a second rate job.

Personally, I'd prefer hot dip galvanize. Look at those Armco metal barriers along many roads - they are hot dip galvanized, and many are still in good condition after up to 50 years out in the weather and salt. Hot dip will also coat much or most of the interior of your frame, areas powder coat will not reach.

Take it to a reputable hot dip galvanizer and it will outlast both you and the rest of the car.

A. First off, let's understand that powder coat, done correctly, is a durable finish. I have some outdoor furniture which has now been out in the weather for ten years and which still looks like new, and there are thousands of outdoor applications where powder coat holds up just fine.

Hot dip galvanize is even better, but it does build considerable thickness. The thickness varies from one galvanizer to another, and from part to part, depending of part geometries. You might find thicknesses in the range of as little as .005", or three times that much.

Threads will likely have to be chased with a tap or die, and critical bores may have to be drilled, reamed or honed. The good news is that zinc is soft enough that most of that work can be done with ordinary hand tools.

A. Hi Corey.

It is the pretreatment (before painting or powder coating) that most affects the long-term corrosion resistance. If the shop can phosphatize the car, that's what you would want. If they can e-coat it, that's what you want. Short of those things, the ⇦ this on eBay or Amazon [affil links] is probably the best approach. Powder coating in lieu of painting is likely to cause the problems people warned you about, without significantly increasing the corrosion resistance.

Regards,

A. Even if you could powdercoat a car for the basecoat you would need some way to adhere the clearcoat to the powder coat basecoat. There are only two ways to do that: mechanical scratch or chemical. What you need to worry about is from the time it gets sandblasted to the time it gets a epoxy primer or direct to metal primer because if you get the metal contaminated it will come out later ruining the job. So that is what you have to relay to the sandblaster and the person who is doing the job. The foundation is the most important factor here because after you paint it, you can't lift the paint up like carpet and fix the problems underneath and lay it back down. So keep that in mind if you're going to restore that car.

A. Without disagreeing with the responses above, it is interesting that..

1. Some new cars are powdercoated.
2. It is impossible to visually tell the difference between powder applied and liquid applied paints in many cases.
3. Most white goods are powdercoated.