stretch watercolour paper

How to Stretch Watercolour Paper: Surface Preparation Guide

How to stretch watercolour paper to prevent warping and buckling.

If you don’t prepare watercolour paper before painting, it could buckle and wrinkle from the moisture of repeated washes.

When paper gets wet, the fibres soak up the water and expand. This leaves some areas raised. Then as the sheet dries it shrinks, leaving ridges across the paper (this is called cockling).

This most commonly occurs with lightweight and medium weight paper, but even heavyweight papers that remain stable with light washes of water can start to cockle when more water is applied. 

Luckily, stretching your watercolour surface is pretty easy and it’s imperative to undertake this step if you want to keep your paper flat throughout your painting session. 

You won’t need to prepare your surface in this way if you’re using Yupo paper or Aquabord, or if you’re planning to be very minimal with the amount of water you will apply. But if you’re using regular watercolour paper and applications of washes, you should take this extra preparation step to get the best results.

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Supplies to stretch watercolour paper

  1. Watercolour paper: I recommend either cold press, hot press or rough paper. Make sure the paper is either cotton, or cotton blend. Heavier paper thickness (260gsm+) is preferable.
  2. A tub large enough to soak your paper sheet.
  3. Drawing board to secure your paper to. The board should be larger than the size of the paper you are stretching.
  4. Gac 100 to seal your drawing board.
  5. Flat brush to apply the sealant to drawing board.
  6. Fine tooth sanding paper to sand the board and a mask to protect you from dust.
  7. Gummed brown paper tape to secure your paper to the board.
  8. A sponge to blot wet paper.

Stretch watercolour paper: in 6 steps

Step 1: Seal your drawing board

Drawing boards are most often made from MDF or plywood, so they need some extra preparation to make them waterproof before you stretch your paper. 

Seal the board by applying two coats of Gac 100. Lightly sand the drawing board (make sure you wear a mask). Wipe the sanding dust away, then use your flat brush to spread a thin layer of Gac 100 over the surface of the board.

I would recommend cleaning your brush between each application of Gac, as it dries quickly and is difficult to remove from bristles.

Wait around 20 minutes for the first layer to dry, lightly sand again then apply another layer. Make sure you paint the sides with the sealant too. 

Repeat this process for the back of the board. Wait a day for the board to fully dry and set—then it will be ready to use for stretching.

Step 2: Soak the paper

Dip the watercolour paper sheet in a tub of cold water.

Heavy weight paper (300gsm+) will need to soak for around 20 minutes. A lighter paper (200gsm) should only need 5 minutes.

Make sure the paper is fully submerged, ensuring that all areas of the paper are soaked evenly. Push it beneath the surface, but don’t crease the paper.

When you take the paper out of the tub, leave it to drip dry.

You may need to hang it on a rack over the tub so that all the excess water drips off. Make sure you keep the paper flat though.

Step 3: Lay the paper on the board

Make sure the board is clean. Any dust or dirt on the surface could cause bumps, nicks or transfer over to your finished artwork. 

Lay the wet (but not dripping wet) paper out flat and straight on a drawing board.

Get a sponge and blot the wet paper on the drawing board, so that it absorbs all excess water. You don’t want the paper to be dripping wet, only a little damp.

Step 4: Secure the paper to the board

Using gummed kraft paper tape you will secure the paper to the board. The tape is water activated, so squeeze excess water from the sponge, then dab a small amount of the leftover water from your sponge onto the tape. This will make it stick to the board. 

Place the tape over the edges of the paper on all four sides. Make a border where the tape overlaps the paper. Choose the size of your border, but make sure to try and keep it consistent so it looks neat.

As you stick the tape down, make sure that no air bubbles form. To prevent bubbles forming, smooth the paper with a sponge before all four sides are stuck to the board.

Step 5: Wait for the paper to dry

Wait for the paper to dry. The board should dry flat, not upright, so that the water remains spread evenly. 

Once the paper is completely dry, you can start painting!

Step 6: Remove tape

When your watercolour painting is finished and dry, there are two different ways to remove the tape. The first way is to cut the paper along the edges of the tape with a sharp craft knife—this way you cleanly cut all the tape away.

Alternatively, you could peel the gummed tape away from the paper. To ensure that no small blemishes are made to the artwork, use a hairdryer on a low setting to warm up the tape as you peel, it will make peeling much easier and your tape less likely to rip the paper.

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