Watercolour was Rex Battarbee’s preferred medium. During trips to the Centre, he focused on Hermannsburg and the area around Finke River Aboriginal Mission, where he held an exhibition with John Gardner in 1934. It attracted the interest of local Arrernte people, especially Albert Namatjira. Battarbee returned in 1936 and together he and Namatjira planned a two-month painting expedition. According to Battarbee: 

[…] each was to contribute to the other's knowledge. Rex would teach Albert how to analyse a scene (according to Western traditions) and to handle watercolours, while Albert would guide him around the country and show him places which in those days were unknown to white-men.

Battarbee thus became the catalyst for Namatjira's successful exploration of watercolour, and played a crucial part in the development of the Hermannsburg School.