All forms of cellulose degrade before they melt but natural cellulose can be regenerated by the xanthate process to manufacture fibres, commonly called rayon or viscose, and film, commonly called by its earliest brand name Cellophane®. Cellulose is the natural polymer that makes up the living cells of all vegetation. It is the material at the centre of the carbon cycle, and the most abundant and renewable biopolymer on the planet. Originally, the word rayon was applied to any cellulose-based manufactured ﬁbre and therefore included the cellulose acetate ﬁbres. However, the deﬁnition of rayon was clariﬁed in 1951 and now includes textiles ﬁbres and ﬁlaments composed of regenerated cellulose, excluding acetate. Rayon is the first man-made regenerated cellulosic fibre, with a serrated round shape and smooth surface. It loses 30-50% of its strength when it is wet. The fibre is sold as artificial silk.