How to use spray on touch up paint

On my newish 2003 there is a small spot down near the driver side front tire where the pain is missing. It’s about the size of my thumb on the very bottom portion of the car body. I thought with some light sanding I could get some auto paint from a local auto parts store and some primer and take care of the issue to make sure the rust stops and no more paint is loss. My question is what should the outside temp be for the best results of applying the primer paint and then the paint itself? Also given where the spot is getting spray off of the tire and such, is there anything special I should do.

It’s not worth the effort required to spray directly onto a spot that small. Clean the spot to remove wax and other residue that will hinder adhesion of the new paint. Spray the paint into the cap and use an artist’s brush to apply it to the bare spot. You can build up the void to more closely match the height of the surrounding paint. If you spray, it’s almost impossible to completely mask off the area and avoid over-spray that then has to be mechanically removed to match height. More work than necessary for a small patch job…

How warm does it have to be outside for the paint to seal properly?

North of 70 degrees F and south of 90 degrees F. That’s what I use as a guideline and I’ve painted a lot of cars, trucks and RV’s.

If it is spray paint, you can prepare the spot as @TwinTurbo‌ suggests, and then mask the area outside the prepared are. Masking tape is used close to the spot, then tape newspaper around the spot and the a couple of feet away from the spot. Tape the paper together so that there is a continuous cover to prevent painting where you don’t want it, with the spot you want to paint in the middle. It is like a sheet the surgeon’s use for operations that covers all the areas but where the make their incision. When you have the areas you don’t want to paint completely covered with enough paper that the paint won’t soak through and mess up the pane beneath, you are ready to spray. Start spraying on the paper about 6 inches away from the blemish and then sweep across the blemish. Go back and forth making sure not to stop on the blemish. Soon, the entire blemish will be covered and you can stop. If you really want to do the job right, use a primer first, but spray on a very thin layer.

Agree with the others. If you must spray, mask off the tires and other areas you don’t want paint on. When you get done, you will still need to sand the over spray area with micro grit sandpaper (like 2000 grit) and hand or machine polish the spot with rubbing compound and polishing compound.

Don’t be afraid. If your car has factory paint, touch up paint can easily be removed with laquer thinner without harming the factory paint. Try the touch up. If you don’t like it, wash it off. if your car has been repainted, all bets are off.

For someone who has not done auto painting (including myself), getting one of those small touch up paints in the bottle with a small brush ($5) might be better for a small area. Clean it well and apply very thin layers of the pain with the brush. Better yet, buy a fine brush from the art’s store and use that one. When you are done, let it dry, then if your paint is not even, mask around it and wet sand with a very fine sand paper.

I have fixed some scratches this way and the next buyer did not notice it, until I pointed it out to them.

If your existing paint is a metallic color, brushing it on will never look right. Even spraying a small area is doubtful. If it doesn’t have to be perfect, spraying will probably come closer.

Most shops that mix paints in large quantities for body shop use can also custom mix a single stage paint in a spray can. Your car probably has a base coat covered by a clear coat from the factory.

I wouldn’t sand anything. Clean, try touchup with a brush, see how it works.

Given I won’t see 70 or above temp wise till next spring, and have no way of doing it indoors/garage, I am guessing I will just need to wait. Any suggestions on what I can do till then to hopefully make sure rust doesn’t grow/get worse.

Duct tape

Put a piece of duct tape over the section lacking paint till I can do the repaint in the spring?


thanks will do that this weekend

Why not just spray paint in sub-optimal temps? Use a hair dryer/heat gun to help it along, if needed. Enamel-based paint dries in colder temperatures than water-based paint does.

Not saying it’ll be factory, but it won’t rust. Buff it out and finish in better weather.

Hillbilly solution, put 1/4 inch hole in a piece of paper or cardboard, no overspray target paint application more or less.

Best way I know is to spray paint into the cap of the can, then use a Q-tip to dab paint onto the area you want to paint. Do it several times, allow time for it to dry, then repeat. Be patient, it will look OK, not great. DON’T SPRAY IT DIRECTLY, you’ll overspray and mess it up. Control, take your time. Rocketman

Sorry . . . gotta be at least 70 degrees or it won’t stick. Put the car in a garage and use a hair dryer to warm things up. Rocketman.

The hir dryer is a good idea, but once the paint tempt ure drops below 70F, curing will stop. You would need to keep the area warm for up to 24 hours to get a complete cure. The writing on the bottle or paper with the box may provide curing instructions for both time and temperature.