The following are shading techniques except?

Shading techniques help artists show light and shadow in drawings. Common methods include blurring, cross-hatching (crossing lines), and pointillism (using dots).

Bleaching is a process that removes color, not a shading technique. Artists use bleaching in photography or fabric work, not in traditional drawing shading.

All other options are actual artistic shading methods. Only bleaching is unrelated to the technique of creating shadows in drawings.