I had an enquiry from a customer who was using watercolour paper to paint with acrylics (they wanted a particular size of paper
to paint on). To create a less absorbent surface the customer wanted to gesso the paper, but found it was buckling. I did some research which I would like to share with anyone considering a similar path…
Always use a heavy paper, 140lbs / 300gms as a minimum, although the thicker the better to minimise the paper buckling / cockling).
Apply light coats of gesso. You can thin Gesso with water to reduce the heaviness of coats.
Apply many thin rather than few thick coats.
Work with a wide flat brush (to allow for smooth application with few brush marks), apply in many coats, allowing them to dry thoroughly. Watercolour paper will always move when you apply water to it, so using gesso which forms a hard surface, you may need to apply coats to front and back.
Subsequent layers should be brushed on in a single direction. So first coat in portrait, then second coat in landscape for example. If you experience buckling then gesso the reverse of the paper with brush strokes at the opposing degree (Side ‘a’ portrait, side ‘b’ landscape). Don’t be tempted to gesso as if you are emulsioning a wall!
The same method can be employed with cartridge paper – but again the thicker the better.
If you are looking to paint with watercolour on gessoed paper remember that gesso has significantly less absorbency, so watercolours will behave very differently on gesso compared with a ‘raw’ paper. There are grounds that will mimic the absorbency of watercolour – such as Daniel Smith’s watercolour ground.