How to prime a canvas with gesso: coats, drying times and sanding

Gesso is the white primer that goes between the canvas and the paint. Golden says it gives the surface "tooth" so paint grips. Winsor & Newton warns that raw canvas in direct contact with paint is likely to rot over time. Many canvases are sold ready-primed (Winsor & Newton's come with at least three coats); this guide is for raw canvas, or for adding coats to make a ready-made one smoother or better suited to oils.

How many coats?

The two manufacturers put it slightly differently, so here are both. The right number also depends on how absorbent the canvas is (Winsor & Newton).

How to prime the canvas

1. Stir the gesso and protect your work surface.

   

   Some settling in the tub is normal, so stir it well first (Golden). Lay the canvas flat on a covered table. Wear old clothes: dried acrylic is hard to get out of fabric (our note).

   You should see: a smooth, even white with no thick sludge left at the bottom of the tub.

2. Careful: don't over-thin. Golden recommends adding no more than 25% water.

   Thin a little gesso for the first coat.

   

   Winsor & Newton suggests thinning the first coat with a little water so it goes on more easily and soaks into the canvas. Pour some into a separate dish rather than adding water to the whole tub.

   You should see: gesso that flows a little more easily off the brush but is still white and opaque.

3. Brush the first coat on in one direction.

   

   Brush in one direction only, pressing firmly so the gesso goes into the weave (Winsor & Newton). Keep the layer thin: Golden says thin layers flex with the canvas, while a single thick coat may crack. Carry it round the edges if the sides will show.

   You should see: an even, thin white layer. The weave may still show through. That's normal for a first coat.

4. Let it dry for at least an hour, and wash the brush.

   

   Gesso can be touch-dry in one to two hours, and Winsor & Newton says to wait at least an hour between coats. Golden says 1 to 3 hours, depending on conditions; its gesso dries to the touch within about 2 hours above about 18 °C (65 °F) and below 70% humidity. Rinse the brush straight away (see how to clean acrylic brushes).

   You should see: a surface that feels dry and isn't cool or tacky when you touch an edge.

5. Sand lightly, if you want it smoother.

   

   This step is optional. Golden recommends wet sanding: dry sanding builds up heat that gums up the sandpaper, while wet sanding gives a better result with less dust. Use a fine paper and a light touch on canvas. On its sandable gesso, Golden advises wiping the surface with a damp, soft cloth afterwards so the next coat sticks.

   You should see: ridges and brush marks softened, without patches worn through to bare canvas.

6. Brush the next coat across the first.

   

   When the first coat is dry, apply the next one in the opposite direction (Winsor & Newton). This coat doesn't need thinning. Crossing the strokes fills the gaps the first coat left in the weave.

   You should see: a more solid white, with the weave less visible.

7. Finish with a coat in the same direction as the first.

   

   Keep alternating direction for as many coats as the table suggests, letting each one dry. Winsor & Newton says to apply the final coat in the same direction as the first.

   You should see: an even, opaque white surface with fine brush lines all running one way.

8. Wait at least 24 hours before you paint.

   

   Winsor & Newton says it's best to wait at least 24 hours before painting on a gessoed surface. Golden notes that thicker films and cooler, more humid conditions slow drying considerably, so allow longer in a cold room.

   You should see: a dry, slightly toothy surface that takes a test brushstroke without lifting.

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