I am a huge fan of AIM's weathering chalks. They are perfect for weathering but also may be used to add color to wood, plastic and foam structures. I use Light Gray chalk on all my wood kits to age the wood before highlighting the pieces with yellow, red and black chalks. I prep all my styrene model pieces with a light grey paint, then use AIM chalk to add all colors except white. White chalk can be used to age asphalt and gravel roads. Do yourself a favor and add AIM chalks to your modeling gear in Red Rust, Dirty Yellow, Grimy Black, Light Gray and Dirty White.