Thomas & Percy Learn About Mixing Colors

S1, E1: Sir Topham Hatt is having a long line of coaches painted for the parade, but he only has three colours: red, blue and yellow. He wants more colours. As Thomas and Percy think for ideas, a workman accidentally knocks over the red and blue paint, combining to make a new colour: purple. Soon the friends are mixing all the paint to learn what other colours they can find.