A great deal can be achieved with pure line drawings, but some ­situations require instruments that can create flat areas or surfaces. If surfaces are used in part of a sketch it stands out very clearly from the rest of the drawing.

Hatching, which consists of individual lines, comes very close to a drawing made with surfaces. But making hatching can be extremely ­tedious and time consuming. In addition, hatching only achieves monochrome suggestions of space or the nature of a material. In contrast, the implements for creating surface areas can be used rapidly, and using multiple tone values can heighten the depiction of space. Materials and surfaces can be drawn in a way that is much closer to nature, while a number of the instruments used to create surface areas can produce more authentic shadows.

Solid tone (opaque), Halftone (transparent) and Structured Surface

A pencil drawing coloured with watercolours is a delightful mix. Generally, it is difficult to draw in pencil on coarse, thick, watercolour paper and therefore a smoother paper must be used, but this does not easily allow several layers of watercolour to be applied. A compromise is necessary. As few as possible layers of colour should be applied in order to avoid damaging the paper. On this account this technique is not a pure watercolour but a colouring. The use of watercolours allows the important things to be easily separated from the unimportant, and the com­position is simplified. When not all of the drawing is coloured and it thus becomes clear where the focus lies, the concentration makes the depiction more interesting.

Watercolours generally take the form of pressed, dried colour pigments with which different shades or intensities of a basic colour can be obtained by mixing them with water. This mixing also gives the water­colour a glazing, i.e. translucent, quality.

Layers of watercolour can be placed one on top of the other, provided you have the necessary patience, as you must wait until one layer has dried before applying the next one, if you wish to avoid the new colour blending with the earlier one. In ­using watercolours you generally work from light to dark areas on the sheet. At the brightest part of the drawing there should be no layer of watercolour, just the white of the paper

The translucent quality of watercolour paints makes them suitable for depicting shadows. You do not always have to use a watercolour based on black that depicts shadows as a grey film and darkens the area of col-our beneath it. Depending on the particular mood of the drawing, shad-ows can also be made using dark violet, dark blue or dark green hues.

A colour gradient to depict vaulted areas or the sky can be easily produced using watercolours.

• First the basic colour required is mixed. The area that will finally have the deepest colour is painted first; this is generally done with a size 12 brush. Then the brush is very gently washed in a glass of water and excess water equally gently removed by using a ­paper handkerchief. The brush still holds the same colour, but the intensity is slightly reduced.

• Now painting is continued on the still wet paper, again covering only a small area at a time. This procedure is repeated until theentire area required is painted or until the brush holds water only, without any trace of colour.

The usual practice was for the colour itself to be mixed with an opaque pigment such as lead white, which gave it a ‘body’ and great chromatic intensity. This made it ideal for decorative work, and as time passed its uses became less and less concerned with the devotional and were increasingly purely decorative. By the 17th century, although religious miniatures continued to be executed in watercolour or ‘body’ colour, the medium was becoming more associated with secular subjects such as landscape, or the decoration of fans. ‘Bodycolour’ was also known by the French term ‘gouache’.