How is a picture hidden with chalk?
Blacklight has been a very effective tool for chalk artists since the discovery of the effect of ultra-violet light to phosphoresce certain chemicals creating colors otherwise invisible. Special invisible blacklight chalk (actually it is white under normal light) is usually applied over an area of the picture that is already saturated with white chalk. Then by very lightly and carefully drawing light areas only and skipping the darker areas (reverse drawing), brilliant pictures can be pre-drawn and concealed until a black light causes them appear seemingly from nowhere. Steps to hide a blacklight picture: 1. Scrub in a heavy base coat of clean white chalk. Use cross hatching. Rub it in good and scrub in a second coat of white. Be sure not to create any distracting patterns or smudges. Do not blend after the second coat with your fingers. Some artists sand the paper with a sanding block to assist concealment of the hidden picture. 2. Everything that touches the white area must be very c
