I use charcoal in the planning of a painting. Usually multiple tiny sketches to work out the distribution of darks and lights in the final painting. At this small scale, details can’t be considered – which at this stage, is a good thing. In these ‘thumbnail’ sketches, possibilities and potential designs can be created with ease. The advantage of charcoal is the range of tones, from full black to almost white paper. Its very easy to create, by suggestion, many of the details which will later be introduced into the painting.
If only the actual painting was as easy. Watercolours have some of this feature, where the dark colour on the paper can be thinned to almost white with the addition of water. Because transparency of colours in watercolours is part and parcel of the technique, the thinned out colour produces bright clean washes as the colour of the paper shines through.
For a time I was trying to introduce some of this method into my oil paintings. The fact of the matter is that oils don’t have sufficient transparency for this to work well. If white is added, to lighten a colour, it produces an opaque ‘milky’ effect, lacking everything – transparent sparkle or strong highlight. Also the ‘mechanical’ weave of the canvas now very noticeable, unlike the rougher texture of watercolour paper, is not an attractive finish in a painting.
However, in the early stages of the oil painting, I use shadow colours to try and get the ‘roughing out’ effect of charcoal. Also, as with watercolour but using White Spirits, I wash some of the darker colours into areas which will later be covered with mid and highlight colour. This is, in fact, the traditional recommended practice in oil painting – transparent shadows and opaque highlights. It would seem as if I’ve just gone round in a large circle and arrived back at the starting point. But its not quite the starting point. The difference is that by using a technique similar to watercolour, the shadow colour is applied and allowed to flow into sometimes random patterns and shapes to later develop into a final interesting surface. This is especially useful in large flat featureless areas, such as the blue of a sky or a large expanse of flat green field. There is nothing as daunting as having to fill in an area of a painting which doesn’t have a feature to focus on. Having an under layer of random shapes does help to introduce variety.
In this video you will see this in practice, especially in the sky. The random patterns created by the Prussian Blue wash dictated the cloud shapes and produced a less contrived cloud pattern.