How to Stretch Watercolour Paper

How to Stretch Watercolour Paper

Why do you need to stretch watercolour paper?

Watercolour paper likes to buckle. It will buckle at the slightest hint of moisture, at least that’s how it can seem sometimes! Buckled watercolour paper isn’t so nice to paint on and the water ends up pooling in the most unfortunate parts of your work. Painting on a flat surface is far more pleasurable, it doesn’t feel like you’re fighting the paper, you’re in control.

The heavier your paper the less likely it is to buckle with moisture and if you normally paint on paper that is >500gsm buckling probably won’t be an issue for you. But most people paint on 300gsm or less and at those weights you’ll certainly notice because the common way of attaching paper to the paint board, using masking tape, does nothing to stop buckling.

Why Does Paper Buckle?

Buckling happens when water stretches the paper fibres by different amounts. When you wet the front surface of your paper the fibres there will take in the water and be stretched more than the dry fibres in the back surface (and any dry fibres on the front). This difference in fibre length causes the sheet of paper to bow, bend and buckle.

To overcome this artists stretch their paper by soaking the whole sheet in water with the result that all the fibres are stretched by an equal amount and to their maximum length. The paper is then firmly secured so that when the fibres dry they are unable to return to their original short length. They are held taut at that maximum length and will stretch no further even if more water is subsequently added. You are free to paint as wet as you wish!

Watercolour paper attached to board showing buckling
Watercolour paper attached to board with masking tape – notice the buckling.

What You’ll Need to Stretch Watercolour Paper

You’ll need:

  • Watercolour paper
  • A drawing board (I like these waterproof gatorfoam boards)
  • Gummed paper tape
  • A wide paint brush (or a small sponge)
  • A jar of water
  • A bucket or bowl large enough to take your paper (or your bath tub)
  • A craft knife
  • A pencil and ruler (optional)

board, paper and tape for stretching watercolour paper
Board, paper & brown gummed tape.
ruler, pencil, brush and water useful when stretching watercolor paper
Ruler, pencil, brush and jar of water.

Many people just use masking tape on their watercolour paper, it gives nice clean borders. But it’s no use for stretching, for that you need gummed tape. The adhesive on gummed tape is activated by water and penetrates into the fibres of the paper to form a really strong bond. The brown version is more common but you can actually get it in white as well.

7 Steps to Stretch Watercolour Paper

1. Preparation: Get all the items together as listed above. Cut your gummed tape to size beforehand and, optionally, mark out the border edge with the pencil and ruler. You can just about make out the lines I’ve made in the photo above left, I use them to ensure the tape is gummed parallel to the paper edge.

2. Soak: Next soak your paper in a bowl or tub of water. 5 – 10 minutes is about right for 300gsm weight, be careful not to leave it for too long or you might damage the paper’s sizing.

watercolour paper soaking in bowl of water
Paper soaking in a bowl of water.

3. Tape it down: Let the excess water drip off the paper then lay it carefully down flat on the board. Wet the brush (or sponge) in the jar of water and use it to dampen one of the gummed tape pieces, make sure not to over-wet the tape and take care not to drip wet adhesive onto the paper. Use the lines you marked out earlier as a guide when attaching the tape to the paper and boards. Repeat for the other three sides.

4. Leave to dry: When done lay the board flat to dry, preferably overnight.

watercolour paper soaked and gummed down
Watercolour paper: soaked and gummed down

Tape Slip
Oops! When you don’t tape wide enough and the gummed tape comes off!

5. Paint: You can now enjoy the delights of painting on a surface that remains flat no matter how much water you choose to throw at it.

6. Cut it out: When you’ve finished your piece you’ll have to cut it away from the tape that’s on the board. Cut at the paper edge, sliding carefully under the paper. You can do this with a craft knife, here’s mine:

Still Life Painting of Knife, pencil, cone and pot
A Craft Knife and a Few Other Things (Acrylics on Paper)

stretched watercolour cut off board
Gummed Tape to be Removed

7. Clean up: Wet the gummed paper tape that’s left on the board and peel it off when the adhesive is reactivated. You wouldn’t want to do this with the paper still in place as you’d run the risk of ruining your work.

Watercolour paper stretched and unstretched
Stretched paper (left) and not (right) – notice the buckling on the unstretched piece

One side effect of using brown gummed paper is that you’re left with a brown border which you may not like as much as the white border you get with masking tape (as mentioned earlier white gummed paper is available in places though not as common as the brown). You can, if you want, cut the gummed tape off completely. I generally prefer not to.

Stretching paper is not particularly difficult to do, you’ll get the hang of it after a couple of goes and you will definitely enjoy the experience of painting on flat paper – give it a go!

Interested in other useful art techniques? Learn how to make your own Stay Wet Palette to keep your acrylic paints wet.

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