Watercolour technique can be described as painting on paper using transparent colours, mixed with arabic gum, diluted in water just before use. Water is thus the main protagonist of this technique, and the cause of the exceptional transparency and luminosity of the paintings.

This is achieved because when the water evaporates, the colour pigment can be painted on in very thin layers which allows the paper's texture to be seen through the paint.

Another defining aspect of watercolour is the speed it dries, which obliges the painter to work fast and to have a clear idea of what he is painting from the beginning. This fact makes it the ideal technique to work in the open air and convey the changing tones and light of nature.

However, one of the difficulties of this type of painting is that, if you make a mistake, it is usually impossible to rectify. This is why executing a successful watercolour is no easy task, although, as ever, practise makes perfect.

A little history
Watercolour is one of the oldest techniques known. Its origins hark back to Egyptian times, who applied it on papyro, first with flat ink and then with fading ink to achieve chiaroscuro. In the eighth century the Chinese were using this method to paint on silk and rice paper. In medieval Europe it was used to decorate manuscripts, for which they used water-based pigments, thickened with an egg derivative. Medieval frescoes were also painted with a pigment mixed with water and later thickened with white paper. Later other types of darker, water-soluble paints emerged that were very similar to watercolour, such as the so-called gouache, a material that is still being used today.

Art critics believe that the oldest watercolours are those depicting scenery and animals that were executed by the German painter Alberto Durero in the fifteenth century, who also completed his natural history sketches with watercolours. The artist of the sixteenth and seventeenth centuries only used watercolours sparingly and, when they did, the custom was to do it in monochrome. Sepia (a black pigment taken from squid ink) was used splendidly in the Italian Renaissance and the German Rhine school.

However, the biggest evolution in watercolours took place in the second half of the eighteenth century with English Romanticism, which glorified nature and natural beauty. The works of William Blake, Thomas Girtin and, above all, Joseph Mallord William Turner are a great example of this. Since the beginning of the nineteenth century, watercolour has become the most popular technique used by amateurs. Despite its past importance, it has not had the same influence in the twentieth century, given that artists prefer to use more expressive means, such as acrylic paint.

Watercolour techniques
These can be divided up into four separate techniques:
- Painting on to paper in a spontaneous manner with small strokes, without any preparation, that is to say, without having previously sketched or measured the subject.
- Drawing with a soft pencil and later colouring in the different areas on the paper.
- Using damp paper or damp watercolour. The paper on which we are going to paint is dampened and then, with the brush heavy with colour, small strokes are brushed on and the paper inclined to let the colour run and achieve a shade. Once the first layer is dry, further layers can be added.
- Using dry paper or dry watercolour. This method consists of applying soft layers, on top of the other, once the previous layer is dry. These colour layers give the painting more depth, acting as a background that influences all the subsequent colours painted on to the paper.