Disperse dyes can be used with various techniques and will readily colour synthetics such as polyester, nylon, cellulose acetate, vilene, viscose, synthetic velvets and PVC. They can also be used to colour plastic buttons and fastenings. Their effect is less potent on polyester, due to the molecular structure, allowing only pastel through to medium shades. Polyester fibre contains pores or canals within its structure which, when heated to 100°C, expand to allow particles of the dyes to enter. The expansion of the pores is limited by the heat of the water - industrial dyeing of polyester is carried out at 130°C in pressurised equipment!