Cernit polymer clay biscuit cernit polymer modelling clay is soft and pliable it can be permanently hardened by baking in a domestic oven at 130c for 15 to 30 minutes giving a porcelain like finish all the colours are intermixable to create other shades and tones a great range of skin tones which would be ideal for making puppets or dolls also suitable for creating your own jewellery beads 500g