Last week I held a demo at Opus Art Supplies in Victoria on glazing over a grisaille, and glazing as colour correction. It was a lot of fun, with many thoughtful and curious questions from the participants.
Here is a summary of the important points that were covered:
Grisaille (black and white underpainting)
– I use Ivory Black and Titanium White.
– Paint your grisaille a couple shades lighter than you want the final product to be, as the glazes will make it darker.
– It should be “finished” enough to be a standalone painting. Don’t save any corrections for glazing – everything you do in the grisaille will show up and will only be more difficult/impossible to correct later on.
– I use Eco-House Damar Medium.
– A basic glazing medium can be made with 1 part stand oil to 3 parts mineral spirits (give or take). Sometimes, this medium will not be sticky enough and will bead on the canvas.
– A better medium is to use 1 part damar, 1 part stand oil, and 5 parts turpentine (again, give or take). This is very sticky with a beautiful shine, though it is smelly and not compatible with mineral spirits.
– Use a sable brush to avoid brushstrokes as best as possible.
– Keep glazes thin – not too much paint, and not too much glaze on the canvas (to prevent drips).
– Build gradually – it will take several layers to get to a finished product.
– Mix optically – layer blue over red rather than mixing purple.
– Allow glaze to dry fully between layers. Do not work on half dry glaze as it becomes tacky and will pull/pill, looking blotchy on the canvas.