Hi!
It's a given. Did you know that even the old Testors Enamels in the square bottles can go bad? Well, that same applies to ANY water or Alcohol based Acrylic. High Temperatures and Severely low ones can destroy the Bond between the Pigment and Carrier. "Pigment-A substance giving a color to a mix of natural or manufactured colorants."
"Carrier- A manufactured or natural base from which paints are made .It can be any numerous natural or chemical Compounds. Both can be severely affected by environments where stored, Or, other outside influence such as U.V.Light!
Note: It's been My experience with Metallic coatings to let them Gas out for a full week Before tryng to clearcoat. AND it's always best to use the Mfgrs. recommended Gloss or Semi-Gloss Clear-Coat. The ONLY one I have not run into problems with here is " Rub-N-Buff" This clearcoats easily after about two weeks of gassing out( If that's the right terminology referring to their product)