Watercolor painting is a beautiful and relaxing art form, but nothing is more frustrating than watching your paper buckle and warp as you paint. Even if you've chosen 300gsm watercolor paper—the weight often recommended for water-based painting—it can still become wavy. So, why does this happen, and how can you prevent it? In this guide, we'll break down everything you need to know about watercolor paper, why it buckles, and the best ways to avoid and fix it!


Why Does Watercolor Paper Buckle?

Watercolor paper reacts to moisture because it expands when wet and shrinks as it dries. If the paper is too thin, it lacks the strength to return to its original flat shape, causing it to stay wavy. However, even thick paper can buckle if the material it's made from doesn’t handle water well.

The Role of Paper Material

Watercolor paper is made from different materials, and this greatly affects how it behaves with water:

  • Wood Pulp Paper (Cellulose Paper): This type of paper is more affordable, but it has several drawbacks. It absorbs water unevenly and slowly, leading to patchy paint application, duller colors, and increased buckling.
  • Cotton Paper: High-quality watercolor paper is made from 100% cotton, which is more flexible and absorbs water evenly. This means your colors will look more vibrant, and the paper is less likely to warp.

While cotton paper is more expensive, it provides a much better painting experience. However, if you’re using wood pulp paper, there are ways to prevent excessive buckling.

How to Prevent Your Watercolor Paper from Buckling

If you don’t want to invest in cotton paper or want to make the most of your current supplies, try these methods:

1. Use a Watercolor Block

A watercolor block is a pad of paper glued on all four sides, except for a small section where you can insert a palette knife to remove a finished painting. This structure helps keep the paper flat as you paint, reducing warping significantly.

 
2. Stretch Your Watercolor Paper

Another option is to pre-stretch your paper, though this method requires extra time and effort:

  1. Completely soak your sheet in water using a sponge or by submerging it.
  2. Tape it down onto a sturdy board while it's still wet.
  3. Let it dry completely before painting.

Once dry, the paper will be taut and less likely to warp when you add water. However, this method can be time-consuming and may weaken the paper, making it more fragile.

 
3. Tape the Edges of Your Paper

A simpler alternative is to use washi tape or masking tape designed for delicate surfaces. Secure all four edges of your loose sheet to a flat surface before painting. This helps keep the paper in place and minimizes warping.

 
How to Fix Wavy Watercolor Paper

If your paper still buckles, don’t worry! Here’s how to flatten it after your painting is dry:

1. Press It Overnight
  • Lightly mist the back of the painting with water.
  • Place a clean sheet of paper or fabric on top.
  • Stack heavy books or a flat board on top and leave it overnight.


2. Iron the Paper

For a quicker fix:

  • Lightly mist the back of the painting with water.
  • Cover it with a clean piece of fabric or paper.
  • Use an iron on low heat to gently press the paper flat.

Be careful not to over-wet the painting or use too much heat, as this can damage the artwork.

 

Set Yourself Up for Success!

Understanding how watercolor paper works can make a huge difference in your painting experience. If you want to learn more about choosing the best watercolor supplies, make sure to download my free guide to watercolor supplies, where I cover everything from paper types to paint and brushes!



I hope this guide was helpful! Happy painting!