Bamboo is an ecological renewable alternative to hardwood. It is also approximately 16 % harder than conventional hardwood usually used for cutting boards. The two tones are a result of using natural light bamboo and the darker bamboo is steamed bamboo. Steamed bamboo gets its color from being "cooked" to perfection, literally, a result of the heating process. The color develops when the natural sugar in the wood is caramelized, producing the beautiful honey color. This is permanent and will not wash off. It also allows the boards to be sanded if needed. Bamboo is usually glued with a formaldehyde glue, however, our products are glued together by a high-grade, non-toxic, formaldehyde-free food grade glue.