Paint won’t flow

The Simon’s green paper I ordered from Twinrocker is a perfect weight for watercolor and a good midtone color but on some sheets the watercolor beads up on the surface. Maybe I handled it too much or the paper rubbed on some graphite. To fix the problem I put a few drops of acrylic flow improver by Winsor Newton in my paint water and now the paint flows. Ox gall also works. It is a wetting agent and improves the flow of watercolors.