Now is probably a good time to mention toned paper and how it works. First, let me say it took a good year or so for it to make sense to me, and probably another year after that to figure out how to really use it to my advantage. There is a certain amount of forethought that you need to have if you want to to work for you. In other words, you need to know what you are going to do with the values several stages before you do it. Your lightest light is not the light of the paper - it is the white chalk you will apply. What this means is that as you lay in your darks, you must keep in mind that your full value range is not yet established. Without your lightest light, how can you possibly know how to play your darks and transitions? The tones of the paper are your transitions. At this stage, there are no whites that have been added, so the overwhelming mass of area that does not fall into the shade and shadow category will appear flat. With enough experience, you will be able to see the white without it being there yet. Note that the light portions of the hair, mustache, ear, and face are all the same value. They soon wont be, and knowing this I can leave them the same for now. For those with less experience, I would strongly recommend doing a small tonal thumbnail sketch that shows the full range of values and how you plan to play them before you start the actual portrait.
At this stage, I have slowly built up the darks, both in the head as well as the background. I am still keeping it relatively homogenous - nothing is too much darker than anything else. That will of course change, but If I was standing in front of Patmore and I squinted my eyes almost to the point of closure, all those darks would mash together. That is what I am trying to accomplish here. The following stages will each be what happens as I open my eyes a bit more. The reason for this is to keep things simple as long as possible. A draftsman can have the most beautifully rendered shadows and forms, but if they don't hold together as a unified whole, it will ultimately fail. The parts must belong to the whole, without exception.
I have also started to do away with many of my construction lines. Ultimately, I don't want any lines remaining, just ranges of value. The charcoal is applied in thin, delicate layers, much like the glaze on an oil painting. If you look at this stage next to the last, it almost appears that I have lightened the face, but I have not. It is just that the darks are becoming richer, therefore making the lights appear lighter.
Even though I am knocking all of the darks together, I am still conscious of the science of light. Darkness is merely the absence of light, and in order for light to be absent something has to block it. Let's use Patmore's nose as an example. As it protrudes from his face, not only is the side of it that is away from the light darker, but it also blocks light from passing onto part of his cheek - a shadow cast by the nose, or a 'cast shadow'. Though I am stating what is likely obvious to anyone reading this, it is a principle that is often overlooked when students draw 'shading'. Don't just draw a dark patch on your paper, realize what the cause of the darkness is as well as what the effect will be. Every shadow has a reason for being there, and if you understand the scientific principles of it, then you can not only make a skilled drawing but you can also learn to manipulate it.