This is a question about baking your freshly painted parts in the sun to make them cure faster.

Hey guys
I painted a car wheel yesterday and have had it in an air conditioned building over night for the low humidity. Should I put it out in the sun today to get it to maybe harden up quicker? I was hoping to put the tires on maybe Tuesday and want it as hard as possible…

Will the humidity outside effect it at this point? I just sprayed a good quality spray-can clear…not 2k.

Thanks

This is a pretty basic question that new painters have.

Can you speed the curing of paint by allowing it to sit in the sun?

Heat is used in body shops by painters to cure professional grade paint to allow quicker turn around.

The temperature in the controlled setting is about 140F and can reduce an overnight wait time to a couple hours depending on how the part or car was painted.

Not every job should be cured in this way but if you follow the recommendations of the manufacturer and allow solvents to escape at a proper rate then speeding the curing time with UV spot heaters or booth heaters can save you a lot of time.

However you must understand how paint cures before you go experimenting. If you screw something up in the final stage you are just going to end up painting it again.

The first stage of paint curing is when it is tack free. At that point you can remove your masking and dust will not enter the paint surface. It is probably not a good idea to pull the car from the booth into the body shop and start grinding a school bus worth of paint onto your freshly painted surface but if some dust does happen to get on it you won’t be looking at buffing it out.

The second stage is when the paint has cured enough that you can deliver the car to the customer.

A lot of people misunderstand this part and think that the curing process has been completed but it is important that both you and the customer understand that the paint is still fresh and will need to be treated gentle for the next 30 days.

Because this person used crap synthetic enamel from a can rather then a hardened enamel or urethane he has added another problem. This type of paint is basically unstable. Although its fine for hobby shop use like painting a bird house you really should never use rattle can paint anywhere on your vehicle that isn’t specifically designed for automotive use.

But whether he was using urethane or synthetic enamel the initial curing has already occurred overnight in his garage. By placing the part in the sun he will heat the metal above the temperature of a UV Heater or Booth Heater and this could cause adhesion loss. Basically as soon as the tire mounter spoon hits the edge of the wheel its just going to scrape off and look like crap.

If he wanted to he could possibly leave the wheels outside but only in the shade. This way ambient heat would be enough to allow the paint to cure but then again even in an air conditioned building temperatures are not going to be below 65F so normal curing should occur either inside or outside.

Can you cure Automotive Paint in the Sun?

So the answer is .. Go ahead and put it in the sun because you already used spray can clear which is useless anyway.. and you really need to sand it all off so the tire machine will give you a helping hand..

No seriously..

The answer is its never a good idea to try to cure a paint job in direct sun because not only the surface where the paint is gets warm but the part does too. And you have absolutely no control over how hot a thick metal wheel will get in direct sunlight. If you ever placed your hand on the hood of a hot car in the summer sun and thought you were going to get a burnt hand.. well its just not good to subject your fresh paint to that kind of abuse.

The best bet for wheels is Powder Coating this type of paint is cured in a oven. You can powder coat at home but it requires a dedicated oven that you could pick up at a storage locker auction but its better to let a professional do the work.

After that you want to try hardened urethane. It is as good as you can get in your home garage and is often used by professionals to match a specific custom color of a vehicle.