How to fix a blotchy painted exterior door?

Did you prime first?

I'm wondering if the mineral spirits or whatever finish you had on your door prior was oil-based and is leaching through your new paint? That can be one cause of splotchiness. Although you primed, if you didn't use a primer made specifically for going from oil to enamel (I like Kilz), you'll still get the blotchy spots. Also, red is notoriously hard to get good coverage with - try using a tinted primer. I have the best luck with a medium gray under red. Good luck!

I agree with Joi Lin, oil based to latex does not mix well. Sanding between each coat didn't help any?

I can't truly answer your question, but we had a handyman use Sherwin Williams on our walls in our kitchen and on our cupboards. Both of them gave us problems with blotchy paint spots. The man came back on a Sunday to do the cupboards for the third time (2 coats first time, 1 coat second time, 1 coat third time). With 4 coats he got ALMOST all of it, but there are still a few shiny spots in the finish that shouldn't be there. The wall is worse but it's behind the door when you open it in a small hallway going from our kitchen to outside and I just let it go. Some day I'll go get some cheaper paint and redo it. I've used Behr on that wall before and never had this happen.

sometimes you need to do a final rinse with vinegar and water to stop the action of the stripper

Mineral spirits are kinda oily too, so I would sand, wash real good with TSP, then reprime and paint.

The rest of our house, both interior and exterior, were painted with Sherwin Williams paint and we have had no problem with any splotchiness. Can't decide whether to try another coat or sand, reprime and try the same color in another paint.

It could be because the wrong paint was used, too (latex over oil paint, for example)

There's a simple test to tell you which is which.

First, scrub a small area with a solution of household detergent and warm water. Rinse well and towel dry. Then soak a cotton ball, Q-tip or soft rag in alcohol and rub it back and forth over the cleaned area.

If paint comes off, it's latex and another coat of the same is in order. If the paint doesn't come off, it's oil-based, and an oil-based primer is a must.

Then you have options for the finish coat, and different types of latex or oil-based paint can be used.st, scrub a small area with a solution of household detergent and warm water.

Rinse well and towel dry. Then soak a cotton ball, Q-tip or soft rag in alcohol and rub it back and forth over the cleaned area.

Glad you got a better result this go-round!! :)