Dear Reader,
Welcome back. We've had some harrowing electrical storms this week in Auburn Ca. I mean Shock and Awe sort of explosions happening in the Heavens above...its like some 80's Def Leopard Light Show on Galactic Crack..it was scary and spellbinding to watch. They predict more for tonight.
Any way, I will explain a bit about planes. This is not the only way to paint portraits, but it is an applied theory of understanding the structure of the face and it will help you establish a likeness quickly as well as paint the face in space with a feeling of light. Another method that is very effective, that I don't employ , is the contour approach. This method was used in the Renaissance. Look at the Mona Lisa and see the contours beautifully rendered. Another master of contours was Hans Holbein.
I needed some reference for a painting last summer and I painted my son David outdoors for about 10 minutes. He is not a patient model and I just needed to see how the afternoon light fell on his face with lawn grass reflecting unto the underside of his face.
Okay, this is very important. Every model expresses unique planes particular to them. We are not all Bob Ross cookie cutter models. Some sitters have wider cheek bones, deeper set eye sockets , longer or shorter noses , larger or smaller foreheads etc. It is our job as artists to identify their salient characteristics that make them unique as individuals. Therefore, when a light source is applied to their mug, they will cast distinct and unique shadowing. In fact you could use only 2 values , white and black , and if you copied the shadows cast from a models face accurately you would be able to identify them! Try it.
Now, I used a plein air painters pallete for this outdoor sketch as I really wanted a feeling of afternoon summer light. Notice how the nose has the lightest light. Why? Because is shiny and because it is faceing the light source directly . Its very close to a 90 degree angle to the source of light the Sun. All the other planes are " Falling Away" from the light source at an angle approaching a parallel to the light source. Sounds kinda complicated? As I have taught students this concept, it takes a little bit of practice, but once you get it , the light bulb turns on and you are on your way.
Now I have drawn lines to mark off the edges of the planes on little David. Look at the nose. This part is tricky but well worth the time to think it through. The front plane of the nose is facing the light. As the side planes move away from the light their value is darker ...but they are technically in the " Circle of Light" ( kinda ripping off Meet the Parents ) . We will se a temperature change. A slight cooling of the warm light. I used white, Cad yellow light , yellow ochre , Cad Red , W&N true Magenta ( more on this Mighty Magic color later...for those fans of getting that Sorolla Look ).
I will add more to this post...just absorb this first. Because what comes next is a marvelous tool to get outdoor light rendered accurately. And that is the color temperature of " Cast Shadows " ...See the color difference in the cast shadow in the eye socket versus the sides of the jaw and under the chin.....?

S signifies Shadow and L signifies Light