I haven't completed the outline of the composition but have added the sky background to the areas I am happy with. Some of these sky areas will have other colours, related to the tree, 'melted' into them to suggest distant twigs from the ones in the main composition. I shall do this by adding the colour and, once dry, wash over the area again with pure water. I add again here that I never use tap water as it contains chemicals and chlorine. Purified or demineralised water can be purchased from any supermarket.