Vallejo model paint thickening the bottle

I can't speak for Vallejo specifically since none of mine have dried up. But my track record with dried or thickened acrylics isn't good. An exception is Stynylrez primer, that usually takes mixing with a Badger power mixer. But it's not that it's dried just settled and will never mix back in by hand with a mixing stick.The power mixer does the trick in that case. Any truly dried acrylic I've encountered is usually junk if trying to thin them back out. Thus far anyway.

All you can do is try them out and see what you get.

I've been using Vallejo Model Air paints for years. I have had a few settle out and a few just plain thicken. In both cases, I added distilled water and mixed with my Badger battery powered mixer. All of them came back and are completely usable.

Stay Safe.

Jim