During his late phases, he was still able to make coherent paintings. His sisters forced him to, to earn money. There's still something frightening about them though.. usually the cat's eyes.
I was introduced to Wain via a Zippy the Pinhead strip, in which Griffy explains that creeping insanity is the only way to make a cute cat artist interesting. Jim Davis for example remains so annoyingly sane that the public has gone ahead and simulated madness for him.
So, his art got way better. Not surprising. Looks kinda like the effect of LSD more than schizophrenia to me, though. That wasn't around though, maybe psychedelic mushrooms? According to TeflonDoc's link, seems like our artist friend may have been just experimenting. Really neat video anyway.