I like to paint on foamcore board. There are a number of reasons for this, but it also has its problems. Not the least of which is that the stuff is not designed to be painted on. In fact if you buy good quality foamboard you may find a little note on the label, or the website, which tells you it is positively not recommended that you paint on it. It curls up, quite dramatically - definite potential for free-form sculpture!
I suppose one of the advantages of being self-taught is that you may be more likely to try unusual surfaces as substrates for painting. But the corresponding disadvantage is that you have to find out for yourself how to prepare such a surface, if you are daft enough to continue to want to paint on it. For someone like myself that sort of trial-and-error thing is quite daunting.
However I remain attached to foamboard (not physically). It gives a completely smooth surface - no tooth. And I like that as a starting point, maybe because for much of my life drawing on smooth cartridge paper was the only way I felt I could create art...it doesn't bounce like a stretched canvas does when you get into the paint with your hands, as I do have a tendency to do, and I find that give distracting. It has some depth, more than hardboard although not as much as a canvas, so you can hang it without a frame (working out how I wanted to do that is one of the practicalities I mentioned earlier) and its very light. It's also cheaper than artist quality wooden panel, which shouldn't be sneered at when you're experimenting with styles and stuff, and you can get eco and ph neutral stuff...
So I had to work out how to use it without it curling. One plus is that my starting point of covering it with tissue paper means if it curls it does it before there's any painting on it to get damaged, as soon as the medium soaks in. So I had to find out about sealants and polymers and stuff, which curl it a bit as you put them on, but if you can flatten it again afterwards you are go for painting! I think of it as a curing kind of process, you have to treat both sides of it the same so that the curling tendency cancels itself out.
The other practicality I mentioned is hanging the finished piece. This is a matter of personal taste of course, but I wanted a frameless finish, which would kind of float on the wall. So I've gone with a wooden cradle, like the one you would use to stretch a canvas on, made slightly smaller than the foamboard and mounted on the back of it. With eyelets on the inside faces of this the picture hangs flat against the wall, and appears to float. Just as I wanted it too.
