Waterproof MODESTONE notebooks are the result of many years of product development. The idea of waterproof notepads was born when the inventor, Kalle Kinnunen, was serving in the Finnish Armed Forces and his important notes from NCO school were destroyed by water. The biggest challenge was to find a perfect substitute material for paper. After extensive research and countless tests, MODESTONE stone paper was finally developed. It is resistant to water and grease, almost indestructible and is not eaten by insects. At the same time, it is an environmentally friendly choice, as MODESTONE paper is made from 80% CaCo3 (calcium carbonate) and 20% HDPE (polyethylene). Waterproof MODESTONE stone paper has another amazing feature: you can even write your notes on it with a key or any other sharp object.