Technical Painting question

My roadster is painted with tractor supply satin black, I painted it a couple of years ago. I had to repaint a door yesterday and it dried flat. The only thing I did different is - when I painted the car I mixed the paint per the instructions 8 to 1 paint to reducer. Yesterday when I painted the door I mixed it 8 to 2 paint to reducer. I probably screwed up. Will mixing it wetter cause this?
If I screwed please let me know, It won't be the first time I was a dumb ass

 

Usually the Tractor Supply Paint dries slowly compared to the name brand Paints normally used in automotive refinishing. If the paint and or reducer is a couple years old, it won't handle right. It may be impossible to get the satin flattening additive mixed back into the paint as before. You have to use fresh stuff. Mixing it thinner makes you apply it thinner on the panel to prevent runs. If you were "dry" spraying to keep from sagging the paint, the finish will suffer. Did you finish with a good, fine sandpaper before spraying? Did the humidity and temperature as well as spray pressure match up to a couple years ago? Painting is one of those things that demand a consistent environment for consistent results. Even experienced pro's prefer a controlled environment.

 

If you are trying to match an existing finish you absolutely have to follow the same exact procedure you used the first time. Even then it may not match due to temperature variances or air pressure. Scuff it up and shoot it again with the proper ratio. Good luck.

 

Matching one panel to another without any sort of blend on a paint that's years old is going to be next to impossible especially with a flat paint as they actually tend to get slightly glossier with age.

 

Thanks guys! the paint and reducer was what I had leftover from a couple of years ago. I will buy fresh paint and reducer, mix as instructed and paint this weekend as it is supposed to be close to 80 degrees.