Q: Is painting acrylic on top of watercolor on gesso-primed wood archival?
A: Not at all—both mediums are water-soluble and compatible.
Be sure to consult the lightfast information on the labels of both
media. Also keep in mind that watercolors are transparent and acrylics
are opaque. In terms of the gesso on the wood, decide whether you want
to use oil-based gesso for oil paint or water-based gesso for acrylic.
Always remember that you can paint oil over acrylic, but you cannot
paint acrylic over oil, as the acrylic will peel off.
--by Camille LaPointe-Lyons