Classical drawing teaches a step-by-step methodology for establishing proportions and value relationships early in the process of developing a drawing.
Step 1: Straight-Line Block-In
Using all straight lines, I block in the large, basic shapes with soft, erasable, vibrating lines.
I try to spend as much time as possible on this first step. Even though it looks rough and simple, I spent over an hour just to get to this level of development. It takes quite a lot of careful study to establish these big shapes and basic proportions.
Step 2: Refining the Contour
When I feel confident the main proportions are well established, I use a pen-style, retractable eraser and a sharper, harder lead to refine the contour line and add necessary detail.
Often at this stage I find I made an error in my first stage! Smaller details might not fit or fill the space I have budgeted for them. When this happens I lightly erase and lighten the whole drawing, and return to the first stage, to find out how my larger proportion error can be corrected. It's important to move fluidly back and forth between these stages, even though it's tempting to just want to continue forward.
Step 3: Shadow Mapping
Only when I have developed a solid, proportional, and refined contour line drawing, do I start filling in the shadow.
While the subject and the final drawing have many shades of light and shadow, at this stage a divide the drawing into only 2 values: The bare white of the paper for every surface touched by the primary light source, and one even tone of value to establish the shadow shape. I call this "shadow mapping" because the light and shadow should look like two separate countries on a map: Completely enclosed shapes with a clear boundary.
For the first couple years of study, I require all my students to fill in this shadow shape much, much darker than I have here: They have to fill in ALL shadows, including reflected light, to a dark value of 80%, where 100% would be defined as completely black. This is because most artists who have not yet been trained with classical methods tend to make their shadows too light, and their reflected light within the shadow far, far too light. So I am showing a very advanced technique here, where I am only lightly and quickly filling in my shadow shapes. But I can do it, because I now have no trouble making my shadow and reflected light dark enough in my final drawings!
Step 4: Turning Form
This is the fun part! Now that I have fully established all my proportions and contour details and planned out my shadow shapes, I can dive in and enjoy shading the full range of values.
We call it "turning form" or "rounding the form" because until this stage the drawing is flat, like two countries on a map. This is the stage where we "turn", or sculpt the illusion of three-dimensional form.
See how my shadow and even my reflected light is nice and dark? I use only the tip of sharpened pencils for shading, I don't smudge or blend with a fingertip or any tool. The reason I do this, and teach my students to do this, is to develop very refined value perception and pressure sensitivity, skills which transfer instantly to any other medium.
Finally, notice how I am using a couple sheets of translucent vellum trace paper to protect the drawing while I work. I cut and tape down a sheet or two like this so my drawing hand does not smudge the white paper while I work.
A complete, uncut video of me drawing this 18-hour drawing, sped up only 2x, is included in my demo course called "Sadie's Sketchbook". This course is only available to members and to those who purchase a course bundle, it's not available for individual purchase. Course Bundles and Yearly Memberships are currently on sale.