To stretch or not to stretch, that is the question. And the answer depends on how thick your paper is – it is recommended to soak and stretch papers of 140lb or less – and how much water you will use when you paint.
The reason artists stretch paper is to stop the paper buckling or cockling, which occurs when you paint a wash onto an unstretched piece of paper. The wet side of the paper expands and the other (dry) side does not. This is unsightly on a finished painting.

How to stretch watercolour paper demonstration

You will need:

• A roll of gummedtape (four lengths cut to length)
• A piece of waterproof or marine ply
• Watercolour paper
• Sponge
• Kitchen towel
• An old book, ½in. or ¾in. thick

Step 1 - Soak the paper

1. Hold the paper by the edges and submerge it in cold water. Soak the paper for the following times:
• 150gsm (72lb) for three minutes
• 190gsm (90lb) for three minutes
• 300gsm (140lb) for eight minutes

NB - Make sure the bowl or sink is clean and free from detergents, as these can attack the size, causing the paper to become absorbent and unusable.

2. Lift the paper out carefully, using the edges, and shake for a few minutes to rid it of excess water.

3. Place on a board

Step 2 - Wet the tape

1. Using a wet sponge, lightly wipe over a piece of tape twice.

2. Stick the tape down onto the edge of the paper, keeping 1⁄2in. (1.5cm) of the tape on the paper.

3. Take out any air bubbles with your finger. Repeat this with the other three sides.

Step 3 - Leave to dry

Lay the board down at a very slight angle to allow surplus water to drain off. Use a 1⁄2in. or 3⁄4in. book, for example. Don’t touch the paper surface, as you can damage it.

Step 4 - Finish off

1. Mop up the water that drains down with a piece of kitchen towel.

2. Once dry, you will find the paper is stretched tight on the board and ready to use. It should not move when you put paint or washes on.

Are you having problems stretching watercolour paper?

The tape pulls away from the board
• The board may be varnished or the wrong type, such as hardboard.
• Your paper may have detergent on it.
• The tape may have been wetted too much, which has removed the gum.

White lines appear on the paper when painting
• This may be caused by the board being laid flat when stretching and a puddle of water left, which, when it dries, leaves a tidemark.

Dark marks appear on the paper when painting
• This may be due to fingerprints made while handling the paper when it was soaked.

The paper acts like blotting paper when paint is applied
• Detergents may have contaminated the paper, which attack the size.

Below is a video demonstration of stretching paper by Bob Davies

Click here for a guide to watercolour materials.

Click here for a guide to watercolour papers.

Click here for a guide to watercolour brushes.

Click here for how to paint your first watercolour landscape.

Click here for a guide to using masking fluid.