This is another question I’ve heard lately at the gallery (in our gallery we usually describe our works as oil on linen). If you go to a museum ninety percent of the paintings you will see are painted on linen. Linen is a preferred support. In art lingo ‘support’ means whatever surface you are painting on. Linen is a preferred support for oil paintings because the weave is irregular and can add subtle variety and movement to passages in a painting that would otherwise not have enough interest such as a flatly painted area. Cotton, though commonly used, has a very regular pattern that can look odd and simple. On the other hand I saw a group of cool landscape studies by John Sargent at an auction and when I turned them over I was surprised to see they were on cotton. So good work can be done on cotton too. I noticed the Deibenkorn still lifes at a recent show were on heavy cotton so maybe its fine for work that not trying to look traditional. My own theory is that the shape of the linen fiber (if you would cut it and look at it sideways) is a polygon, it has points, and when a brush loaded with paint is dragged across linen it aggressively pulls the paint from the brush more so than the round cotton fiber. For me that’s a good thing. I guess bottom line is the choice of supports effects how the brushstrokes look.