In the late 18th century advances in the science of chemistry added a new method to the textile printing industry, with a technique known as discharge dyeing. The cloth was first dyed completely and then the pattern was printed on it with chemicals which discharged either the dye or the mordant with which it was prepared. The discharge parts of the pattern could then be overprinted or dyed with additional colours if required. This technique was being advertised in the late 1780s but was not widely used until the 19th century.