Shadows - cool or warm?
Gosh I feel like one of the things I harp on about when I am teaching is achieving a glow in the shadows, and in my recent workshop for the Central Coast Watercolour Society it was a topic of focus. As I am travelling around Tasmania and taking photos mostly as reference for future paintings, I have been noticing the light and shadow, and particularly paying attention to how the warm and cool and reflected light affects shadow areas.
As I enjoyed a Seafood Chowder lunch in Hobart by the water, this seagull sat close by and I couldn't take my eyes off the warm (yellow based) and cool (blue based) light in the shadow on the majority of it's body. I know sometimes in class participants may not see this change in temperature as clearly as do, so I hope these photos and tips will help you to notice and understand how we can use colour to be impactful in our paintings even if we can't necessarily see the change.
In general we think of shadow as dark and cool - leaning towards blue/mauve/grey tones. Form shadow however is lighter and warmer in temperature and a cast shadow (the shadow cast by an object) is cooler and bluer in temperature. If we look at the shadows on the body of the seagull, these are form shadows, and typically a form shadow will have a softer edge as the form curves away from the light, and it will be made up of a mid tone, reflected light and a darker area of shadow sometimes known as the terminator line/zone which is near when the transition from light into shadow, and perhaps a darker area of shadow furthest from the light source.
On the seagull we also see a cast shadow, and this is differentiated by the strong definitive edges. The shadow is cast by the head of the bird and it throws a cool blue shadow with hard edges onto the side ( or shoulder area) of the body.
Another great example of this is a building with a side plane in the shade. The shadow side of the building will often have an area of a warm tone to it, while the shadow that the building casts onto the ground will be cooler and darker. To achieve this change in tone, I apply the shadow area with a mauve mix of Ultramarine Blue or Cobalt Blue and Alizarin, and then lightly drop in a warm yellow - usually Naples Yellow. Dropping this colour in takes a light touch and a still damp first wash. If you paint paint paint the yellow into the mauve, you will mix the paint on the paper and get grey instead of a glow of warmth. If I wanted to cool a shadow even more - for instant the `shoulder' of the seagull I might drop cerulean blue lightly into the mauve wet in wet on the paper.
In the images below think of the upright `wall' of sand as the side of a building.
So what if we can't see it? Can or should we still apply this knowledge of light and shadow in our paintings? I do because I feel that the shadows are what make the light sing. Shadow passages are sometimes a large area in our painting and need to provide interest and description - if we just painted the shadow on the sand above in an a shade of mauve perhaps at minimum with some more depth where the cast shadow meets the `wall' we might still have an interesting painting, but we may not create a dynamic and glowing painting.
I do believe though that the depth of colour is much easier to see than the temperature, so if it doesn't come naturally to you, it is okay for it to take some time to observe deeply once you know the theory behind it.
Using the principles discussed above if I was painting the house in the photo below, I would be adding warm yellow into my damp shadow wash on the shaded planes of the house, and cool bluish tone into the mauve on the areas that i have marked as cast shadows. I usually work the two areas at the same time if they touch, in order to have a natural transition in the shadow, so it is not a dramatic difference. The next question is probably - can you tell looking at it what is a shaded plane/face/wall, and what is a cast shadow? The shaded plane is the wall that is in the shade or on the shaded side of the building (marked below in yellow as warmer), and the cast shadow is a shadow cast by an object blocking the direct light and casting it's shadow shape onto the wall, ground etc (marked in blue as cooler). Ie the power line running from the front top casts a shadow on the wall, the overhang of the guttering casts a shadow under it.
I love the shadows on the side of this boat. I would maximise all of those changes of colour temperature and hue (light to dark), but my cast shadow of boat which falls on the grass would be cool and dark.
This knowledge would also guide my decision to use a cool shadow mix on the left side of the boat to describe the shadows under each piece of jutting timber.
In the coming weeks I will do one or two of these as You Tube videos to demonstrate the warming and cooling off of the shadow colour.
To understand the terminator line a little more this is a great block by Aaron Griffin - https://www.creativebloq.com/how-to/what-is-a-terminator-line. It relates more to figure and life drawing but has a really good illustration.
Edit to add link to You Tube video demonstration of the seagull. Please excuse that he has a bit of a belly full of Muirs fish and chips - I didn't know how round I made him until later!