Pastels, charcoal and wax crayons have their strengths, but Martin Child discovers a new breed of crayon that is far more versatile

Surrealist painters discovered that rubbings of textured objects, especially wood, leaves and fabric, could be used to form the basis of a painting. Max Ernst often used the technique, known as frottage, as a springboard for his highly imaginative images. This method is perpetuated in many art departments. Pastel, oil pastel, charcoal and wax crayon can all be used to good effect in rubbings.

However, pastel and charcoal smudge easily and are not always appropriate for over-painting. Oil pastel is much better, but resists water-based paints and is also quite soft, resulting in the loss of fine detail. Wax crayon offers crisper detail, but colours are difficult to blend - and, again, wax resists water.

Karat Aquarell Watercolouring Crayons from Staedtler are excellent for making rubbings, as they are harder than oil pastels but slightly softer than standard wax crayons. These soluble colours mix together well, and the pigment can be manipulated with the application of water. This allows paintings with an under-lying texture to be easily achieved.

The fact that these firm crayons are hard-wearing, while the strong pigments readily intermix, means they are also useful for making dry drawings. By adding water, smooth, streak-free blends can be created.

More pressure increases the amount of pigment applied to the page, so colour washes are simpler to produce than with traditional watercolour techniques. When the paper is dry, further layers allow an almost unlimited pallet from the 24 colours available.

Another technique, which Ernst employed, was to scratch into the surface of paint to add detail. Working a thick layer of Aquarell crayon over a painted area and scratching into the surface readily reveals the under-lying colour. As it is much easier to achieve hard edges with these crayons than with oil pastel or wax crayon, fine details can also be drawn in.

Wet paper allows these crayons to skate the surface, leaving fluid marks. Another way to increase fluidity is to dip them into water for a few seconds before drawing. Then they flow like a well-loaded brush.

Wax crayons are often perceived as a material for primary schools, but secondary art departments should not overlook these quality crayons. Hard-wearing, free-flowing and soluble, they are satisfying to use. Although not cheap, Aqua-rell water-colouring crayons are extremely versatile and useful for student work, even up to sixth-form level. If they were available in the 1920s, I am certain that Ernst would have delighted in exploring the many possibilities they offer.

* Staedtler (UK), Cowbridge Road, Pontyclun, Mid Glamorgan CF72 8YJ. Tel: 01443 237421. Stand J58