Aitchison finished Dog in Red Painting in a new studio overlooking Cambridge Circus, London, which he took in 1975. The painting is notably larger than much of his previous work, reflecting the size of his new working space. An expansive quality entered his work at this time, and an increase in size was accompanied by a further simplification of subject content. As the title suggests, Dog in Red Painting resumes the theme of earlier works like Purple Landscape (1956, Private Collection) and Yellow Painting (1957, Private Collection), both of which rely almost solely on colour for compositional structure and artistic effect. The inclusion of a dog in this work, Aitchison’s first Bedlington terrier, Wayne or ‘Wayney’, creates a playful antagonism with the otherwise abstract qualities of the picture. The work is executed with the artist’s characteristic technique of rich colour and thin application. Helen Lessore noted that ‘His paint has always been extremely thin, scrubbed into the canvas.’ The saturated colour of Dog in Red Painting was developed using a fine layer of paint which did not sit on the canvas; the canvas has rather been stained with paint, filling the pores and appearing to emanate from it. Referring to a time when he attempted to use thick paint, Aitchison said ‘that was no good because there was no tension left; the surface of the canvas had gone and when I lose that, everything has gone.’ To retain this thin surface in his work, Aitchison developed a technique of ‘itching’ or ‘nudging’ paint around on the canvas. Speaking to Tate Gallery conservators in 1994, he said ‘I itch the paint from the inside to the edge to get a line… and finally drawing the edge with a small knife.’ This is the case with Dog in Red Painting where the horizontal band of vermilion in the upper register of the painting is clearly defined with a small, incised line. The grain of the canvas is clearly visible beneath the paint, moreover, a common feature of the artist’s work which suggests his disciplined approach to surface finish.