A common problem nowadays is oil painters who buy pre-gessoed canvases. The problem? Those premade canvases are made with acrylic primer. Oil cannot connect to acrylic and you get either delamination [why the Smithsonian won't use acrylic primer under oil] or leakage.
Instead, make your own canvasses using what the old masters used: rabbit-skin glue to preserve the canvas and then oil-based primer.
