Different uses of masking fluid in watercolour, as featured in The Artist August 2017 issue. Credit – Paul Riley

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Discover Tony Paul's top tips on how to use masking fluid in watercolour painting, including a tutorial on using masking fluid to paint a bird in watercolour. 

What is masking fluid?

Masking fluid is a liquid latex-based product. There are many makes of masking fluid and some grip more aggressively than others.

Why use masking fluid?

Masking fluid allows you to preserve white space and fine lines in your piece, by stopping the paint from touching the paper.

Masking fluid saves us time. In my painting of the coal tit below, I wanted to create wet-in-wet washes as a background to the study of the bird. Cutting in around the bird would have been difficult so I masked out the bird and the branch it stood on with Daler-Rowney masking fluid. When dry it has a yellowish tinge, which is easy to see on the paper.

Top Tip! Always try out the combination of a new paper or masking fluid on a piece of scrap paper before committing it to a painting. Settle on a paper and fluid that work well together and see how long it is before the dried mask proves difficult to remove.

What do you use to apply masking fluid?

You can use an old brush to apply the fluid as it will ruin a good one, however, I prefer to use a Colour Shaper angle chisel, No. 0, firm. This has a grey rubber pointed tip, looking rather like a brush. When finished, leave the masking fluid to dry on the Colour Shaper and then rub it off.

Applying masking fluid, as featured in the Leisure Painter October 2018 issue. Credit – David Webb.

Can you apply masking fluid onto damp watercolour paper?

No, don't apply masking fluid to damp paper, or dilute it, as the masking fluid may adhere more strongly and cause the paper to rip. Masking fluid is best applied to naked paper. 

Looking for more masking techniques? Head over to Jane Ward's article on masking techniques for watercolour painting.

Can you put masking fluid over painted areas?

No, applying it over dry washes can cause problems. Either the colour underneath lifts patchily or the paper’s surface pulls off.

Applying a wash over masking fluid, as featured in the Leisure Painter October 2018 issue. Credit – David Webb.

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Watch video below, by the late Terry Harrison, on how to use masking fluid.

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How long does masking fluid take to dry?

How long masking fluid takes to dry can depend on a number of factors, such as the brand, the environment you’re in and the paper you're painting on. Don’t try to speed up the drying process of either the masking fluid or subsequent washes with the use of a hot hairdryer. If you use a hairdryer, keep it very gentle.

How long can you leave masking fluid on?

Remove the masking fluid as soon as possible. If you've applied the masking fluid but find you're unable to start the painting in the near future, rub it off again and re-apply just before you start painting.

Over time, dry masking fluid breaks down into an inflexible, leathery scab that's immovable. Don’t leave the fluid on the paper for more than a week and if its surface is no longer tacky, remove the masking fluid quickly. The longer that masking fluid is left on paper, the more difficult it is likely to be to remove. The more absorbent the watercolour paper, the more likely it will be that the masking fluid will adhere to it and possibly be difficult to remove without tearing the surface.

How to remove masking fluid

Remove masking fluid by gently rubbing it off using a fingertip or a soft eraser.

Removing masking fluid, as featured in the Leisure Painter October 2018 issue. Credit – David Webb.

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Now you know how to use masking fluid, why not try it out for yourself? Browse a range of masking fluids available for purchase, here.

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How to use masking fluid – tutorial by Tony Paul

1. With a bit of practice, the finest lines are possible but you can also apply broad sweeps of fluid with the Colour Shaper. Here, you see the masking fluid applied and left to dry.

 

 

 

 

 

 

2. The first wash was applied, working over the dry masking fluid. Then the second wash was applied rapidly, wet on wet, over the first to give the effect of out-of-focus winter trees in the distance.

 

 

 

 

 

 

 

 

3. Twigs and branches, first in an ochre green then a purplish grey, were painted over the top of the dry washes. When these were dry, I rubbed off the masking fluid. It came off easily.

 

 

 

 

 

 

 

4. The few places where masking fluid had not covered the bird completely were lifted off with a damp brush and kitchen roll. I left others on the branch to help with its texture. The formerly protected area was now ready for painting.

The finished painting, watercolour, 7x5in. (18x13cm).

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Want to learn more watercolour techniques, or need a refresher, now you know how to use masking fluid in watercolour painting? Our ultimate guide to watercolour painting is here to help you learn everything you need to know about the basics of painting in watercolour.

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