The Canvas

My materials are in and I've started to prepare the canvas for painting. The first step is to give it a preliminary stretch and allow the fibers to adjust to the frame. I've loosely tacked it to a stretcher. It will get two coats of a diluted glue (or sizing, in the technical jargon) before I apply the ground (a white, semi absorbent oil-based coating that supports the paint film). The sizing serves to seal the canvas and prevent oil in the ground and paint from seeping into the canvas fibers. Traditionally this was done with a glue of animal origin. Isinglass from the swim bladders of russian sturgeons, or natural gelatin from rabbit skins are two of the more common variants of historical glues. Many painters today still use these glues. I prefer a polyvinyl acrylic adhesive (PVA) for my canvasses. PVA glue has largely replaced the animal hide glues for conservators around the globe. It has the advantage of being ph neutral, non-yellowing, and less hygroscopic than other glues, yet it remains totally reversible. This would allow an experienced conservator the ability to separate the paint film from the canvas, should anything happen to the canvas. Kind of a terrifying thought, but it's reassuring to know that the painting could be preserved even if the canvas was damaged by moisture, mold, or insects. A great read about adventures in art conservation is Jonathan Harr's The Lost Painting.