When with pens you draw lines, with pencils you draw stains or smudge the area, as if you are drawing with a brush. By drawing strains with different degrees of spacing concerning them (or with distinctive line widths), you can make an illusion of different brightness values. I bought https://remingtonvjvis.mdkblog.com/40781179/the-fact-about-ink-drawing-for-beginners-that-no-one-is-suggesting