The higher the temperature used during dyeing, the better the colour will be. Clothing and fabric manufacturers, however, recommend low temperatures for washing. Materials such as wool, cotton and linen usually dye well at higher temperatures. Most wool blends, for example, dye perfectly at temperatures of 90/100 °C. Felting occurs mainly due to sudden changes in temperature. For wool, it is important to heat and cool slowly. Cotton can also usually be dyed at 50 or 60 °C, or sometimes even at 90 °C. It is possible to dye at temperatures below 40 °C, or even at 0 °C, but it is advisable to experiment first with small samples to avoid thermal disappointment or repeated rubbing. If heated and cooled gradually, wool can withstand high temperatures. A lot of information on dyeing different materials is available on the Internet. At your own risk, experimenting with water temperature can lead to excellent results.