I told him about some older paint I attempted to use.
It was a disaster
Here was Doug's recommendation:
With old paint in a can, i hold the paint can by the top and bang the can on a wooden table top or a 2” x 4” in rapid motion, but not real hard, for one full minute.
This sets up a high frequency mixing action that takes the paint from a separated state in the can to colloid solution as intended by the manufacturer. Did you clean the case with lacquer thinner or Acetone, maybe parts cleaner?
If you did the liquid material collect in the micro pores of the part.
When an external coating is applied, the liquids migrate from the pores, violate the chemicals in the applied paint and a wrinkle finish is usually the result.
Isopropyl alcohol works best as a cleaner, flashes off without a residue and does not wrinkle the paint.
I also store my paint upside down.
When it is turn over before use and mixing the mixing processes has already begun.
Just a couple thoughts that may be helpful. Thanx