How to use masking fluid › The Weekend Beckons

This page contains affiliate links. As an Amazon Associate I earn from qualifying purchases. Read the full disclosure.

Traditionally, watercolour artists don’t use white watercolour paint for the white of their scene. They leave the paper unpainted where they want the whitest whites, like sun glinting off water or highlights on glass. Leaving paper unpainted can be tricky. One wrong move and the paper you were trying to leave white suddenly has a bit of paint on it and there’s no erasing it. To help reserve the whites, many watercolour artists use masking fluid.

I use Grumbacher because I like having the masking fluid tinted light orange. This ensures I always know where it’s applied. It’s also easy to use and the jar doesn’t fuse shut, which I’ve had happen with other brands. It also doesn’t tear the paper when removing it, which is an issue I’ve had with other brands. It does smell pretty terrible though.

It’s fairly easy to use with just a few tips to ensure you have success with masking fluid. First, let’s look at the tools to apply masking fluid.

Use an old brush you don’t care about. You need to know that tt will RUIN your brushes. Don’t think you’ll wash your brushes quickly – the moment that masking fluid touches your brush, you’ll only be able to use it for masking fluid in the future. So only use a brush you will never paint with again because it’ll have dried-up masking fluid gunk in it permanently.
Better yet, don’t use a brush to apply it. I discovered silicone brushes and have had nothing but success using them for applying masking fluid. You can buy a set for fairly inexpensive and you’ll be able to do tiny dots, thin lines, or wider spaces with ease. Clean-up is a snap too, just wipe them with a bit of paper towel.
You can use tooth-picks, skewers, or other disposable items to apply masking fluid as well. If you’re creative, you could use sticks, pine needle branches, or other items to apply and get different effects.

Now let’s look at how to apply it.

First, gently mix your masking fluid. Don’t shake it or you’ll get bubbles which are trickier to work with.
Dip whichever tool you’re using to apply into the masking fluid. With some practice, you’ll learn how to avoid getting giant blobs of masking fluid on your paper, unless you want that, of course. You can lightly remove some of the masking fluid by wiping your brush on the edge of the jar.
Then apply it to the paper. Do your best to apply a thin layer. If your masking fluid is applied thickly, it can take a very long time to dry.
Let it dry completely. It’ll dry to a rubbery layer on your paper where you applied it. Ensure it’s dry all the way through before you start painting with watercolours or else you run the risk of accidentally getting fluid on your good watercolour brushes and ruining them permanently.
Paint with your watercolours and let those dry completely.
Remove the masking fluid by rubbing it with your fingers. There you go – you have reserved the whites!
You can use masking fluid over top of dried watercolour, and paint over the reserved whites. This allows you to use masking fluid for all sorts of techniques.

Watch me demo how to paint an ocean wave using masking fluid on my YouTube channel. I just use three colours – ultramarine blue for the sky, phthalo blue (green) and yellow ochre for the whole scene.