I never get rid of old tooth brushes. To get the speckled texture on this piece I made a stencil with tracing paper and scrap paper. I traced out the area that I wanted to remove from the paper and cut it out with an xacto. I lined it up and blocked out the rest with scrap paper. Then I used a tooth brush that I dipped in ink and then pressed the bristles of the brush with my thumb to create a small splaying effect.
Give it a try and do it on a practice piece first.
Don’t use the tooth brush on your teeth ever again.