How to Stretch and Tape Watercolour Paper So It Stays Flat

Have you ever finished a watercolour painting, only to find the paper has gone wavy and lumpy? Learning how to stretch watercolour paper fixes this. Wet paper swells, then shrinks as it dries, and that is what makes it buckle. This Haanz Art Guide shows you two simple ways to keep your paper flat: taping it down dry, and a full wet stretch. Both work at home or in the classroom.

Why watercolour paper buckles

Paper is made of fibres. When water soaks in, the fibres swell and the sheet grows a little. As it dries, it shrinks back unevenly, so you get hills and valleys. Paint then runs into the low spots. Thin paper buckles the most. Heavy 300gsm paper moves much less, but can still curl with big, wet washes.

In Sri Lanka’s humid weather, paper also takes longer to dry, so it stays soft and loose for longer. Fixing it to a firm board before you paint makes a big difference.

What you need

• Watercolour paper. Bomeijia Watercolour Pad, 300gsm, A4 is heavy enough to tape down dry. For larger work, try Fabriano Artistico Rough, 31 x 41cm, 300gsm. Lighter sheets such as SeaKing Watercolour Paper, 160gsm, A3 need a wet stretch for big washes.
• A firm, flat board. The Drawing Board, A3 is 7mm thick with a smooth surface. The Mont Marte Drawing Board, A3 works well too.
• Tape. Nyoni Artist Masking Tape is low-tack, holds paper and peels away for clean white borders.
• A wide flat brush or clean sponge for wetting the paper. A large Flash Synthetic Hair Flat Brush is ideal.

See more papers in Drawing Papers For Watercolours and boards in Drawing Boards. Prices change, so see each product page for today’s price.

Method 1: How to tape watercolour paper down dry

This is the quickest method. Use it for 300gsm paper and for small or medium paintings.

1. Place the paper. Wipe the board clean, then lay the sheet in the centre.
2. Tape the long sides first. Press a strip of masking tape along one edge, with about half the tape on the paper and half on the board. Smooth it firmly with your thumb. Then tape the opposite side.
3. Tape the short sides. Finish the other two edges the same way.
4. Seal the edges. Run a fingernail or the back of a spoon along the tape so water cannot creep underneath.
5. Paint, then wait. Leave the painting taped until it is completely dry. It will flatten again as it dries.
6. Peel slowly. Pull the tape away at a low angle, moving outwards from the painting, to avoid tearing the surface.

Method 2: How to stretch watercolour paper wet

A wet stretch is the traditional way to keep lighter paper flat. You let the paper swell first, then fix it while it is still expanded. As it dries, it pulls tight like a drum. Masking tape does not stick well to wet paper, so for this method artists use gummed paper tape (the brown tape you wet to activate) or staples on a wooden board.

1. Wet the paper evenly. Brush clean water over both sides with a wide flat brush or sponge, or dip the sheet quickly in a clean tray. Do not scrub the surface.
2. Let it relax. Wait a few minutes until the paper softens and expands.
3. Lay it on the board. Gently smooth it from the centre outwards with a clean towel to remove air bubbles. Blot away pools of water.
4. Fix all four edges. Apply wet gummed tape so it overlaps the paper and the board, or staple close to the edges.
5. Dry it flat. Leave the board lying flat, away from strong sun and heavy rain spray. A room with a fan helps on humid days. Allow several hours or overnight.
6. Paint once dry. The paper should feel tight and flat before you start.

Tips and common mistakes

• Drying too fast. Hot sun or a hair dryer close up can make the paper shrink unevenly and pull the tape off. Dry it gently.
• Too much water. A soaking-wet sheet takes ages to dry and may lift the tape. Damp and evenly wet is enough.
• Weak tape edges. Always press the tape down firmly, or water will creep under and spoil your border.

To choose the right paper weight, read our Watercolour Paper Guide: What GSM Means. When your paper is ready, try the exercises in Watercolour Techniques for Beginners, and keep spare sheets dry with Storing Art Supplies in Humid Weather.

Frequently asked questions

Do I need to stretch 300gsm watercolour paper?

Usually not. For most paintings, taping 300gsm paper down dry on a firm board is enough. If you plan very wet washes over the whole sheet, a wet stretch gives extra security.

Can I use ordinary masking tape?

Yes, for the dry tape method. A low-tack artist tape is easier to remove cleanly. Test it on the edge of your paper first, as strong tape can tear the surface when you peel it.

Do you deliver islandwide?

Yes. We deliver across Sri Lanka in 2–5 working days, with cash on delivery, card or bank transfer. You can also visit our shops in Boralesgamuwa and Horana, open every day from 9 AM to 6 PM.

Not sure what to choose? Call / WhatsApp the Haanz team on 0711 515 515 and we’ll help you choose the right watercolour paper and board for your painting.

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