Arches Aquarelle is acid-free and chlorine-free, made from 100% cotton fibers for strength and stability. The paper is made from natural gelatin in tube sizes and air-dried. It can withstand rubbing, scratching and smudging while maintaining the original intensity of the watercolor. It uses no optical brighteners, so its natural white color will not yellow with age and its archival value is guaranteed. It is excellent for watercolor, gouache, pen and ink, acrylic and calligraphy.