How to Use Masking Fluid for Watercolour: Step-by-Step Guide
Masking fluid keeps highlights, fine lines and small details free of paint while you work broad washes over the top. Here's how to apply it, paint over it and remove it cleanly without tearing the paper.
How to use masking fluid: apply it to dry watercolour paper with an old brush, silicone shaper or ruling pen, only where you want to keep the paper white. Let it dry completely, then paint over it freely. When the paint is fully dry, rub or gently peel the masking fluid away with a clean fingertip or a rubber pickup eraser to reveal clean, untouched paper.
Solid Solutions Masking Fluid is a liquid masking fluid made with natural rubber latex for watercolour and mixed media. It dries to a flexible film that paint won't get through, then rubs away when your painting is dry. Australian made.
Shop masking fluid →What Is Masking Fluid?
Masking fluid is a liquid resist. You paint it onto the areas you want to protect, and once dry it forms a flexible barrier that water-based paint can't get through. When your painting is finished and dry, you remove the masking film to reveal clean paper whites, or the colour you protected underneath.
It's most often used in watercolour, where highlights and fine details are hard to keep clean during broad washes. It's also useful with acrylic (test first), ink, gouache and mixed media whenever you need crisp reserved shapes, sparkles, textures or precise negative space.
| Quick reference | Solid Solutions Masking Fluid |
|---|---|
| Base | Natural rubber latex |
| Best on | Dry watercolour paper (good quality, heavier weight) |
| Also for | Acrylic, ink, gouache and mixed media (test first) |
| Tools | Old or dedicated brush, silicone shaper, ruling pen or applicator stick |
| Removal | Rub or peel off once the paint is completely dry |
| Clean up | Soap and water, straight after use |
| Sizes | 250ml, 1 litre and 4 litre |
How to Use Masking Fluid, Step by Step
Start with dry paper
Make sure the paper or surface is completely dry. Masking fluid should not go onto wet or damp paper. Strong, good-quality watercolour paper is least likely to tear when you remove it.
Mix it gently
Gently shake or roll the bottle for an even consistency, without whipping air bubbles into it.
Apply it
Brush, dot or draw the fluid only where you want to keep paint out. Use an old or dedicated brush, a silicone shaper or a ruling pen, and rinse brushes in soapy water often. Keep layers thin for cleaner edges and easier removal.
Let it dry completely
Let it dry naturally at room temperature until it's no longer tacky, before you paint over it.
Paint over it
Paint your washes and colours freely over the masked areas with watercolour, gouache, ink or acrylic. The masked areas stay protected underneath.
Remove it
Once all the paint is completely dry, rub or gently peel the masking fluid away with a clean fingertip, soft cloth or rubber pickup eraser. It rolls into small rubbery pieces. Work slowly to protect the paper fibres, and remove it as soon as practical, as it gets harder to lift over time.
Clean your tools
Wash brushes and tools with soap and water straight away. Once masking fluid dries in the bristles, it's very hard to get out.
Advanced Techniques and Tips
Mask, paint, let dry, then mask again. Repeat to build complex highlights and depth.
Flick with a toothbrush or dab with a sponge for stars, spray, foliage and granular texture.
Use a ruling pen or fine applicator stick for sharp architectural edges, lettering and fine filigree.
After removal, soften hard edges with a barely damp brush for a more natural blend.
Acrylic can form a tougher film over the mask and tear along the edge instead of separating neatly, so always test on a scrap first.
Papers, canvases and paints behave differently. Try a small amount on a scrap of the same paper with the same paint before a finished piece.
Masking Fluid Questions & Answers
What does masking fluid actually do?
It creates a temporary resist layer that blocks paint from reaching the surface beneath it. After painting, you remove the dried film to reveal preserved whites or underlying colour.
How long should masking fluid dry before painting?
Let it dry completely at room temperature until it's no longer tacky. Painting over it while it's still wet can smear the mask and let paint through.
Can I paint directly over masking fluid?
Yes. Once the masking fluid is completely dry, paint over it normally. It resists water-based paint applied on top.
How do I remove masking fluid?
Wait until the paint is completely dry, then rub or gently peel it off with a clean fingertip, soft cloth or rubber pickup eraser. It usually rolls into little rubbery pieces as you rub it away.
What happens if I leave masking fluid on too long?
It can become harder to lift and increases the risk of damaging the paper. Remove it once your painting is dry and you no longer need the resist.
Can I apply masking fluid to wet paper?
No. Always apply it to dry paper and let it dry fully before painting over it.
Can I use masking fluid on top of watercolour paint?
You can, once the paint is fully dry, but it may lift or disturb some paint when removed, especially delicate layers. If you're reserving highlights over a coloured area, test first on a scrap piece.
Do I need special paper for masking fluid?
You'll get the most reliable results on good-quality, heavier watercolour paper. Thin or soft paper tears more easily during removal, especially if the masking layer is thick.
Why did masking fluid tear my paper?
Common causes are weak paper, masking applied too thickly, removing it before the paint is fully dry, leaving it on too long or rubbing too hard. Use stronger paper, apply thinner layers and remove it gently once everything is dry.
How do I stop masking fluid ruining my brushes?
Use an old brush or a silicone tool. If you use a brush, rinse it in soapy water often while you work and wash it straight after. Once the latex dries in the bristles, it can permanently damage the brush.
Can I thin masking fluid with water?
A small amount of water can help for finer lines, but thinning too much may weaken the resist. Always test that it still blocks paint cleanly.
Does masking fluid work with acrylic paint?
Generally yes. Mask an area, paint acrylic over it, then remove the masking fluid once the paint is dry. Test first, because acrylic can form a tougher film over the mask and sometimes tears along the edge instead of separating neatly.
Shop and Related Guides
Keep your whites clean
Solid Solutions Masking Fluid in 250ml, 1 litre and 4 litre.