Layering is the process of applying colored pencil over existing colored pencil. Each new layer strengthens, darkens, shifts, or neutralizes the color underneath.
Anyone can layer, there are no special skills involved.
Successful layering relies upon the pencil's physical properties— how well a pencil lays down and adheres to other pencil, the pencil’s opacity, the pigment load, and whether any extenders, extra binder, or inexpensive fillers in the pencil cause issues with the base layers.
Put simply, bad pencils simply do not layer well and no amount of skill can make it happen. The best a talented artist can do is avoid situations where the layering looks especially bad.
As a user, we can easily test and compare a pencil’s layering ability.
Blending is the artistic process of forming a gradient from one color to another by creating a transitionary middle color between them.
Good blending is the result of good pencil technique, pressure control, understanding of how the two pencils will interact, and choosing pencils wisely to create the best (or worst) blend.
It’s very easy for the tester to alter blending results to say whatever they want. We can make bad pencils look good with good technique and smart pencil selection. It’s even easier to make good pencils look bad by deliberately making poor choices.
As a reader, there’s no way to know if I’m swaying a blending test.
Layering tests how a pencil actually behaves.
Blending tests the person holding the pencil.