Strathmore Artist Trading Cards - 20 Bristol ATC Papers. This paper is great as an ATC base. 100 lb. weight; it is thinner than chipboard, but much thicker than cardstock. Ideal materials for bristol paper are pencils (charcoal, traditional, mechanical, and colored), ink, pens (felt-tip, pigment, rollerball, and gel), and light washes (ink, dyes, and watercolor), and airbrush techniques. Use by themselves or glue your finished ATCs to the bristol paper for a sturdy backing. Paper measure 3 1/2" X 2 1/2" and comes in a pack of 20.