Rayon production demonstration. Syringe of dye-coloured viscose being injected into sulphuric acid to produce strands of rayon. The colouring agent used here is copper-based, producing a blue colour. The viscose was produced by dissolving cotton wool in the copper complex solution (cuprammonium hydroxide). The cellulose in the viscose polymerises on contact with the sulphuric acid, producing strands of the artificial fibre rayon.