Polycolor pencils use a blend of oils and premium pigments in every color core. These oils along with other binders allow the Polycolor pencil to create dense, even strokes without the use of heavy pressure. The 3.8 mm lead diameter is an added artistic value to these pencils allowing for shading with a broad edge, or fine sharpening for detail work. The end result is a water-resistant, non-toxic pencil that layers and blends beautifully without a waxy buildup.