For a change of pace and a different look, I'll paint oils on paper. It has a different feel and look that's pleasing. Plus it has to be matted and framed under glass, which gives it a different look from the heavier framing for canvas. I use a 100% rag board or paper. Rag has no acid in it so it won't deteriorate like other papers or boards. The surface has to be primed to protect it from the oils. I use rabbit skin glue, it allows the surface of the paper to come through. Gamblin makes a PH balanced primer that would work well on paper. Polymer gesso leaves too many brush strokes. The texture of the paper or board allows me t use softer brushes and different techniques than canvas. I usually use it for smaller paintings and different shapes.