Toning a canvas is deadening the white of the canvas by adding thin layer of color, usually in a light to mid-range value. What color to use? This is a difficult question and especially perplexing for beginning painters. There are many answers.
Some artists always tone their canvases with the same color. Others vary it from painting to painting, Yet, some will tone more than one color on a single canvas. Common colors are a light wash of cadmium red, yellow ocher and a mid value gray. Using an opposing color can create some vibrancy. Cool colors under warm paints and warm tones under cool paints. I often use a light cad red under the blue, letting it peak through. My skies will often have a warm undertone.
Toning can be used for different moods or lighting. Maybe a yellow or orange for a bright, sunny day. A cooler red, such as alizarin crimson or rose madder for a dark landscape. This can create a unity or harmony of color in the painting.
You might pick a dominate color in a painting for your underpainting. I've done this when painting a close up of a tree with the foliage and branches. By toning the canvas, it could save you time with an intricate design. I toned this canvas with a yellow ocher. It made it easier to paint the intricate design. I didn't need to worry about covering every inch of canvas.
"Aspen Dance" 8"x10" oil on canvas panel
I've seen some artists painting each area of the painting with a different color of tone, yellows or reds in the sunny areas and cool colors in the shadows. In "Palo Verde" I put on an underpainting of Cad Orange on all the light in the painting. I wanted an undertone of orange in the painting and this helped to speed up the process and helped to cover canvas without meticulously painting each part of the tree. "Palo Verde" 30"x40 " oil on canvas panel Experiment. Try toning in different colors on each canvas or on one canvas. The choice is yours, no right or wrong.
Happy Painting! Becky