The pared down pictorial language is matched by a rudimentary technique. The ritual paintings are usually done inside the huts. The walls are made of a mixture of branches, earth and cow dung, making a Red Ochre background for the wall paintings. The Warli use only white for their paintings. Their white pigment is a mixture of rice paste and water with gum as a binding. They use a bamboo stick chewed at the end to make it as supple as a paintbrush. The wall paintings are done only for special occasions such as weddings or harvests. The lack of regular artistic activity explains the very crude style of their paintings, which were the preserve of the womenfolk until the late 1970s. But in the 1970s this ritual art took a radical turn, when Jivya Soma Mashe and his son Balu Mashe started to paint, not for any special ritual, but because of his artistic pursuits. Warli painting also featured in Coca-Cola's 'Come home on Diwali' ad campaign in 2010 was a tribute to the spirit of India’s youth and a recognition of the distinct lifestyle of the Warli tribe of Western India.