Why does watercolour paper buckle? And how can I prevent it?

There’s nothing worse than working on a painting while ridges and valleys form on your paper. Painting can be challenging enough on a flat surface, let alone a bumpy one!

So why does paper buckling happen and how can we prevent it?

At the heart of the issue lies the unique properties of watercolour paint itself. Unlike other painting mediums, watercolour paint uses a high water content. When applied to paper, this water can cause the fibers of the paper to swell and expand unevenly, leading to buckling or warping. When it comes to watercolour painting, we like water, and LOTS of water. So we want paper that can handle the amount of water we are throwing at it.

Watercolour paper - quality

That’s where good paper comes in to play. The absorption rate of the paper will depend on the sizing applied to it (and as I’ve mentioned before, the way the sizing is applied varies greatly when it comes to different brands). Good quality watercolour paper like Arches or Fabriano, is specially formulated to absorb water evenly, allowing for smooth blending and diffusion of paint. However, cheaper brands of paper will absorb water too quickly or unevenly and it can cause the paper to warp as it dries.

Watercolour paper - weight

Additionally, the weight and quality of the paper play a significant role in its susceptibility to buckling. Heavier-weight papers, such as 300 gsm or higher, are less likely to buckle than lighter-weight papers due to their increased thickness and durability. Similarly, papers specifically designed for watercolour painting, such as cold-pressed or rough-textured papers, are better equipped to handle the moisture of watercolour paint without buckling.

Pre-stretching watercolour paper

To mitigate paper buckling, artists can take several preventative measures. Stretching watercolour paper before painting is a common technique used to minimize buckling. By soaking the paper in water and then stretching it taut on a flat surface (with framers tape that is activated by water), artists can help the paper retain its shape as it dries. Alternatively, using a heavier-weight paper or investing in pre-stretched watercolour paper can also help reduce buckling.

Finished artworks on watercolour paper can also be stretched post-painting. Simply spray the back of the artwork with a fine mist of water and lay it flat between some boards to dry.