Leighton's work in oil is entirely on canvas. I have encountered no oils on panel or canvas board, although some may exist. Not surprisingly, his oils on canvas appear to be less accomplished overall than his watercolours. This fact is explained in part by the fact that they were painted in the studio well away from the high passes they depict. In these cases he must have imagined colours or interpolated them from watercolours. Despite this, his best oil paintings reveal wonderful things.
Leighton's accomplishment in oil painting came late, if dated paintings from about 1930 and the 1935 painting of Mount Skoki are any indication. The 1930 paintings tend to be dark in tonality and uncertain in handling. Mount Skoki (Cat. # 13) is a rather lifeless production, its colour pallid rather than pale and alive. Nevertheless, in 1935 it won Leighton's acceptance into the Royal Canadian Academy.
His oil paintings of the '40s, '50s, and '60s are often painted over textured and tinted grounds and in this respect are more complex than the earlier works. They include some of his finest works in the medium: the beautiful, high altitude depiction of Mount Assiniboine (Cat #31) reveals the lightest, clearest colour Leighton ever achieved and suggests possibilities that were seldom pursued. This beautiful painting like so many of Leighton's works is ringed round with questions? when and where was it painted, and what was it painted from? was it painted from a high altitude sketch? If so, does that sketch exist? was it derived from a photographs? If so, where was it taken, and did Leighton take it himself or rely on a commercial depiction?
Monochromatic colour, especially greys and earth-colours, could smother Leighton's oil paintings just as pallid monochromes diluted his watercolours. But on occasion his monochrome oil colour rises to a kind of eloquence. Paintings of the Goodsir Plateau (Cat #28 & 29) exploit earth colours and greys with real boldness. These, along with Valley of the Giants (Cat. #37), reveal a characteristic method of handling that appears to dominate his late works. Built upon a heavily textured under-painting, the rock walls and mountain peaks appear to be composed of overlapping slabs or shingles of rock which interact with patches of colour and underlying texture. The large Mount Hungabee (Cat. #15) at 30 x 40 inches huge by Leighton's standards uses this technique to nod in the direction of abstraction.