What is underpainting?
An interesting stage of painting – one often not seen or appreciated because it happens underneath the final image – is underpainting.
Underpainting is the step after the canvas is sealed with gesso and before starting on the final image. It’s one of the first decisions I make when approaching a painting and an important technique in laying down a foundation for an artwork, creating a preliminary layer of colour that acts as a base for subsequent layers of paint. From time to time, you’ll see me use a red underpainting with acrylics, but I use other colours too (and sometimes skip this step entirely).
Why underpainting matters
There are several benefits to underpainting, but overall, it can make a big impact on the look of a finished painting and can help me get started. As a first step, it seals every pore and crevice on the canvas, ensuring that if I miss a spot in the final painting the colour from the underpainting with peek through. It’s also an easy way to get over any mental hurdles and eliminate the intimidation that comes from being stared down by a blank white surface. Just ‘messing up’ a pristine canvas can be a real help some days!
One of the most important advantages of underpainting is the depth and dimension it can add to the final painting. A complementary colour underpainting can create a sense of vibrancy, luminosity and colour intensity in the paint applied over top. For example, a red underpainting can be used for landscapes to create contrast between the red and blues of the scene.
Choosing the right colour for underpainting
Because the big benefit of underpainting is to deepen colour intensity, the choice of colour for an underpainting really matters. Why that is, and why I often use red can be explained with a bit of colour theory.
To deepen colour intensity, I want to create a dynamic contrast between the underpainting and the main colours in the final painting. For a landscape, this means a red underpainting. Red is complementary (opposite) to blue and green (think land and trees), and ‘hot’ compared to the ‘coolness’ of blue (think sky and water).
On the other hand, if I were painting a predominantly orange scene, I might choose a blue underpainting to provide a cool colour contrast. Again, the opposite colour to the final image: a cool/calm colour to contrast the heat/energy of orange.
You could also use a rainbow of colours underneath which results in a bright and lively painting because all of those colours peek through between the brushstrokes of the final piece.
But as with so many things, it depends. The best colour for underpainting depends on the subject matter and the effect I am looking for. Sometimes I just start with a white underpainting because I like my whites white and my skies to be somewhat softer than they are with an under colour.
Every painting presents a different challenge to solve – some need to feel softer, some need to be bold – and underpainting is a great technique toward the final outcome no matter what. While it may take some practice and experimentation to find the best approach for your specific painting style and subject matter, the effort is well worth it. With underpainting, you can create works of art that truly stand out.
Updated: I've added some thoughts and ideas about using red 'underpainting' to paint over paintings that aren't going as initially planned.