Complex sentence: He was influenced by the watercolour techniques of Thomas Girtin, John Sell Cotman and Peter De Wint, especially their use of the rich blooms produced by applying a full wash and allowing it to dry undisturbed.
Split into simpler sentences: He was influenced by the watercolour techniques of Thomas Girtin, John Sell Cotman and Peter de Wint. Especially their use of the rich blooms produced by applying a full wash and allowing it to dry undisturbed.