What is paper?

Paper is made from two main ingredients: cellulose fibres (found in plant material such as cotton, jute, hemp and wood pulp) and water. Most of the popular papers, such as Arches, Bockingford, Cotman, Langton and Saunders Waterford, are machine-made, on a cylinder-mould machine. Also available are handmade papers, which are made by dipping a mould into a vat of pulp.
 

What are the different watercolour paper surfaces, and how are they best used?

There are three surface textures:
• HP – smooth
• NOT – slightly textured
• Rough – obviously textured
 

• HP Hot-pressed (French: Satine) paper has a smooth, firm surface and takes its name from the fact that it is pressed through hot metal rollers during the manufacturing process. Choose this paper if you work with line and wash techniques, or you want to concentrate on flower paintings or similar types of work in which small amounts of paint will be applied in a controlled manner.
• CP/NOT Cold-pressed (French: Grain fin) is so named because, during the manufacturing process, the wet sheets of paper are repressed by running them between cold metal rollers. The result is a slightly textured surface. Choose this paper if you want a reliable, general purpose paper that will suit most techniques and subjects, whether you want to work with control and detail or in a much more spontaneous way.
• Rough (French: Torchon) paper, as the name implies, has a noticeable, rough texture, which it picks up from the couching felts during the manufacturing process. It is then left to dry, without additional pressing. Choose this paper for broad, expressive work in which texture is important as well as techniques such as dry brush, broken washes, lifting out and scratching back.

Try this simple exercise to see what happens when you apply a watercolour wash to each of the three types of watercolour paper:

1.

With Hot-pressed paper the brushmarks tend to sit on the surface and dry as they are, rather than blend together.

2.

On NOT paper you can create an even colour wash, and this type of paper is also good for other wash techniques.

3.

When you apply a wash to a Rough surface, particularly if the brush is not too heavily charged with paint, you get a more broken colour effect.

What difference does the size and weight of watercolour paper make?

The way that a particular sheet of paper responds will also depend its weight and the amount of size used in its production.

The weight is an indication of the thickness of the paper. So, you could expect a 72lb (150gsm) paper to be light and thin, while a 400lb (850gsm) paper will be much thicker and more robust.
The most popular weight for watercolour is 140lb (300gsm). Measured in pounds (lb), the weight refers to a ream: 500 sheets of Imperial size, 22x30in. (56x76cm) paper. Now, in most countries, the more accurate metric equivalent of grammes per square metre (gsm) is used.

Look for paper that is acid free, because this means the paper does not contain chemicals that will degrade the sheet and cause yellowing. Some papers, including Bockingford and Saunders Waterford, also include a buffering agent, which prevents them from being attacked by atmospheric acids and pollutants.

Paper is sized to make it more water resistant. The size is normally added to the pulp during the manufacturing process. However, some papers are also surface sized by dipping the sheets in a bath of gelatin after they have dried. This makes the paper less absorbent, which means that the colours will be more vibrant and easier to blend. Also, the tougher surface is good for techniques such as lifting out, sponging and scratching through the paint layer without damaging the surface. Cotman and RWS paper have this characteristic.

Which is best, sheets or pads of watercolour paper?

The usual sheet size is 22x30in. (56x76cm). It is more economical to buy sheets of this size and cut them into the smaller sizes you require.

For painting outdoors and for experimenting with techniques and trying out ideas, buy an A4 spiral watercolour pad or a watercolour block.

To begin with, buy one or two sheets of one of the popular 140lb (300gsm) CP/NOT papers, such as Arches Aquarelle, Bockingford or Saunders Waterford. All of these are reliable, good quality, acid-free papers that will suit most subjects.

For testing out ideas and effects, use cheaper cartridge paper, paper off-cuts, or other types of scrap paper – perhaps the reverse side of wallpaper, for example.

With most watercolour papers there is very little difference in the surface texture between one side and the other. Traditionally, with embossed and watermarked papers, the correct side is the one on which the watermark appears the right way round. Other papers have a ‘mould’ side. If you hold it up to the light, you will notice that it has a more regular surface texture than the other side. It is a matter of preference as to which side you choose.

How do I store watercolour paper?

Always store paper flat, either in a drawer or on a shelf. Remember that the surface of watercolour paper is very sensitive. It will easily indent if something heavy is placed on it, and it will even pick up marks from your fingers – so handle with care!

Part four in this series explains how to stretch watercolour paper to prevent cockling