I consider it a minor miracle that this painting of ‘Timmy’ (the cat I grew up with) looks as good as it does today hanging in my home. My guess is that it was painted in the early 1960s. You want to know what material it is painted on? – this part is the ‘miracle’ – it is just an odd piece of cardboard, like the stuff on the back of a legal pad.
If you take the picture off the wall & look at the back you can see that it has warped but otherwise it has held up OK. This in a world where Martha Stewart tells us we need acid free tissue paper to even pack our clothing for a trip.