This is on acid free paper and archival black artist's crayon.
This painting began with a black and white drawing and then I developed it with alternating layers of watercolor and crayon.
The technique I use is archival and will not smudge easily like charcoal and pastel. It is very resistant to fade although you should never hang a watercolor in direct light from a window unless the light is muted. Glass really helps to preserve color and will keep the drawing fresher.
The crayon I use is very permanent and will not blur, smudge or rub off.