Watercolour Paper Guide

Manufacture

There are three methods of manufacture of artist papers, 'hand made', 'mould made', and the standard 'fourdrinier' machine made (used to make cartridge, newsprint etc.). High quality artist papers are made on a mould machine, which provides all the appeal of hand made paper, but without the inevitable variations from sheet to sheet. The beauty of this method of manufacture is the exceptional surface stability found on these papers.

Materials

Watercolour papers are made from two basic types of material. The highest quality sheets contain cotton, which offers very good stability and archival properties. The second main raw material is cellulose pulp chemically created from wood. Some artist papers contain a mixture of the two (e.g. 50% Cotton), providing a compromise between quality and economy.

Surfaces

There are three main surface textures to watercolour papers, HP, CP (NOT) and Rough. HP stands for 'hot pressed' and is the smoothest paper suitable for high detail work. CP stands for 'cold pressed' (and is also known as NOT - as in 'not hot pressed') is a slightly textured surface and popular because it is suitable for most types of work. Finally, there is 'rough', which is exactly what its name suggests, suitable for landscapes, seascapes etc., where a heavily textured paper enhances the final piece of work.

Can I use both sides of the paper?

All paper is made with differences between the two sides. With mould made artist papers the sides are called the 'felt side' and the 'mould side'. The felt side is the one that touches the woollen felts first during manufacturer and the 'mould side' is the side that touches the wire mesh around the cylinder called a mould. Both sides of the paper can be used for painting, but the 'felt side' is often considered to be superior. It is difficult to tell the differences between the two sides - you need to look very carefully at the paper to try to see the lines left by the fine wire mesh of the mould.

Soaking & Stretching

Soaking and stretching is recommended when lighter weight papers are used with a quantity of water (e.g. 150g/m², 190g/m², 300g/m²), because the paper will move and buckle/cockle.

Why does the paper move?

When applying water to paper it moves and buckles (known as cockling by papermakers) because the application of moisture to the sheet will cause one side to expand slightly. However, the other side remains dry, and due to the sizing contained within the sheet, does not expand. To counteract this expansion on the wetted side, the paper does the only thing it can and bows and buckles. This is very unsightly for the finished painting and difficult to work with because the paint will pool in the waves of the paper.

How to soak and stretch watercolour paper

1. Immerse the sheet of paper under running water from a tap for 30 seconds to 2 minutes, taking care not to touch the area you intend to paint as the paper is fragile when wet and finger marks will show up in the wash.
2. Place the soaked sheet on a sturdy board.
3. Wet some gummed tape (do not soak) and place around all four edges of the paper.
4. Blot any excess water with a clean paper towel, and leave to dry on a slight tilt.
5. Leave the paper to dry overnight. When dry the paper will be stretched tightly on the board and when water is added with paint the paper will not move.

Important

Troubleshooting

Tape pulls away from paper when the paper is drying

• It is possible the gummed tape has been wetted too long removing too much glue.
• There isn’t sufficient glue on the tape to hold the paper tight when drying.
• There is a problem with the absorbency of the paper (either accidentally induced with detergents (see above) or during manufacturing), which has caused the paper to soak up too much water that makes it difficult for the tape to stick to the paper.

The paper acts like blotting paper after soaking, but is fine unsoaked

• The most likely explanation is the paper has been contaminated with detergents as noted above.

Dark marks are appearing in the wash

• Usually dark marks that appear in the wash are often attributed to finger marks when handling the paper. The paper is especially fragile when being soaked so it is very important to handle the paper with care by the edges.

Thin white lines are appearing in the wash

• Thin white lines are usually caused by a puddle of water being left to dry on the paper. The puddle dries leaving a 'tide mark' which shows up as a white line after application of a watercolour wash.

The paper isn't as strong after soaking and stretching

• If the paper is soaked for too long the gelatine surface can be washed from the sheet. Historically, hand made paper with a heavy surface sizing of animal skin glue needed to be soaked for a long time. This is no longer the case on modern mould made papers and soaking for excessively long periods can reduce the effectiveness of the paper.

How to avoid soaking and stretching

• Use a heavier weight paper such as 425g/m² or above. The paper is thick enough to withstand the moisture applied to it without buckling/cockling too much. The heavier the paper the less it will move.
• Use a watercolour block. Blocks are glued on all four sides pulling the paper tight so it resists buckling/cockling.