Masking is any technique that will help you preserve the white of the paper when you’re painting with watercolour. There are various ways to mask your painting including:

  • Wax
  • Masking tape
  • Paper
  • Masking fluid


Wax resists water, meaning that you can paint over wax and the wax marks will remain white.

  • Use a candle or white crayon to draw a pattern or shape on your paper. It can be very difficult to see what you have drawn, so try to hold the paper in the best light for drawing as you go
  • Paint over your lines

Wax resist

Useful for: Decorative patterns, texture, sparkles on water

Masking tape

You can use masking tape for protecting the paper and leaving geometric shapes and straight lines.
Low-tack masking tape or framer’s tape is vest as standard masking tape can become too sticky if left for a while and can rip the surface of the paper when removed.

Try painting some boats on the sea:

  • Tape across the top of the ‘sea horizon’ line
  • Tear or cut triangles of masking tape to make boat sail shapes
  • Paint in the sea
  • When the sea is dry, remove all tape and paint in the boats and the sky

Useful for: Straight lines, the horizon line of the sea, buildings, small geometric shapes

Masking fluid

Masking fluid is a rubbery fluid that you paint onto your paper, allow to dry and then peel off. It can be beige or blue, so think about what will be most easy to see when you are painting when you buy your masking fluid.
To preserve the white of your paper with masking fluid, you need to:

  • Find the brightest whitest parts of your subject to decide where to paint your masking fluid
  • Apply the masking fluid and allow to COMPLETELY dry
  • Paint over it and allow the paint to COMPLETELY dry
  • Peel off gently using a rubbing motion with your finger

Ways to apply the masking fluid

There are lots of different ways to apply the masking fluid that will give you different marks and effects.

With a brush

Brushes can help you fill in areas and make roundish marks.
Reserve or buy a different brush for using masking fluid as the fluid can dry onto it very quickly and ruin the bristles.
To help minimise this problem, dip your brush into a water and washing up liquid solution and blot before using the masking fluid.

  • Dip your masking fluid brush in washing up liquid solution
  • Paint your shape in masking fluid and allow to dry
  • Paint over the dried shape with as many layers of paint as you need and allow to dry again
  • Remove the masking fluid by gently rubbing it off

Even brushes that have become clogged up with dried up masking fluid can be useful for making scratchy dry-brush type marks.

These watercolour paintings used all sorts of brush marks from old brushes and masking fluid to add texture.



Using a ruling pen

A ruling pen will help you to achieve the finest lines with your masking fluid and give you the most precise control if you want to ‘draw’ it on.

  • Dip your ruling pen into the masking fluid
  • Draw your shape in masking fluid. You will need to keep dipping the pen back in, so practice first to ensure you are confident with getting the right width of stroke. Allow to dry
  • Paint over the dried shape with as many layers of paint as you need and allow to dry again
  • Remove the masking fluid by gently rubbing it off

Useful for: Precise drawing, fine marks, fur


We looked at spattering and splattering paint in the Watercolour brush marks and mark-making blog post.
The same technique apply with masking fluid:

  • Mask off an area of paper so that the masking fluid will only go where it’s intended
  • Use a brush or rubber tip colour shaper or something similar to pick up the masking fluid and then tap it down on the edge of your hand over the paper so that the drops fly off randomly onto it. Practice first so you can get an idea about where the drops will fall
  • Vary height and direction to see the different effects you can get
  • Wait for the fluid to dry before painting over it, you’ll find it takes longer to dry using this technique as it’s quite lumpy

Masking spattering

Useful for: texture, stars, random spots, flowers



Follow the steps above, but use a brush loaded with masking fluid and flick the bristles back to launch a spray of small droplets onto the paper.

Masking splattering

Useful for: Texture, rock, stone, rust, foliage

Other ways to apply masking fluid

Experiment with different ways of applying masking fluid to achieve different marks. Different brushes, card, plastic, twigs, paint it over stencils, let your imagination run wild!

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