Trying out some new panels from Wind River Arts. Just started a painting on one of these and so far I think these are exceptional panels. These first panels I am trying are 1/4 birch with superfine linen surface. Here you can see both the front and back. The priming is lead white.
First, the canvas is glued to the panel and not wrapped around at the sides. The canvas can be removed relatively easily for conservation purposes. This also means that when you order a 9x12, that is exactly what you get - a perfectly squared-off panel of precise dimensions.
The second thing I like is that the priming is a single coating so it is thin. This leaves a lot of texture exposed even with very fine fabric. With some panels I have used, the priming is too thick so that the surface is too much like painting on plastic.
These are expensive panels, but not that much more than much lower quality products. I wouldn't necessarily use them for practice or sketches. Probably should be used for finished and professional work.