Craf-T chalks can shade and blend together for a soft pastel finish or rich deeper shades. Glimmer Chalks will produce several different effects from a sparkle to an iridescent glimmer, depending on color, paper, intensity, and reflective lighting. Metallic Rub-On chalks can be used on hard or glossy surfaces, including polymer clays. E-Z Chalk Enhancer allows you to intensify the colors even more. All non-toxic and acid-free.