Watercolour Basics: Masking Fluid


Keep in mind that I’m not an expert! I’m a hobbyist at best. My goal isn’t to teach techniques for professionals, but for other hobbyists who would like to know some techniques to have fun with watercolour. That being said, I’ll try my best to give good advice! If anyone has links to other resources on a similar topic to this tutorial, please do link it in the comments!

Masking fluid, also known as liquid frisket, is used to protect, or “mask”, parts of your paper, so you may paint over it with ease without worrying about painting around any white areas. It’s often made of liquid latex. It can be a valuable tool for watercolour painting when used well! In this tutorial I’ll try to give you lots of pictures and tips so you can feel confident doing your own experiments with masking fluid.


First things first, get your materials ready! In the image above you’ll see my palette (one home made, and one travel set; anything works, so long as it’s watercolour!), water containers (for clean water and for rinsing), watercolour paper, brushes, masking fluid, eye dropper (this is optional; it helps me when mixing colours), and paper towel/a rag for cleaning up or lifting water/paint.

Masking fluid should be applied before everything else; you can apply it on top of something you’ve already painted, but be prepared for it to lighten, or lift, any pigment you’ve already laid down. Its primary use is to mask white areas you want to keep white as you paint, so planning ahead and knowing where you want it ahead of time is key!

Next you want to prepare the brush or other tool you’ll be using to lay down the masking fluid. Here’s the brush I’ll be using:

It’s a cheap brush that is past its prime. If you’re using a brush to lay down masking fluid, you’ll want to make sure it’s a brush you don’t mind messing up. Over repeated use masking fluid has a habit of clogging up the bristles in brushes, no matter how careful you are, so using one you don’t mind losing is a good bet. 🙂 Other things you can use: Toothpicks, rubber/silicone shapers, toothbrushes, anything you don’t mind the possibility of clogging up with latex. (Keep in mind, synthetic bristled brushes will be easier to clean than natural fibre brushes; the latex may stick more strongly to natural fibres.)

To further protect my brush and make it easier to clean, I’m going to soap it up. Soap makes the bristles nice and slick, making it more difficult for the latex to adhere to the bristles as it dries. You can use dish or hand soap in soapy water, but here I’m using one of my favourite things: The Master’s Brush Cleaner and Preserver.

I’ve had this bottle of brush cleaner for YEARS and I’ve barely gone through any of it. I highly recommend picking up a bottle if you care about your brushes!

Pictured above: Wetting my brush and working up a small lather in the brush cleaner to coat my brush. I gently wipe off any excess (taking care not to wipe off too much), and now that my brush is prepared I’m ready to mask!

Make sure your paper is 100% bone dry. Putting masking fluid to damp paper, even a slightly bit damp, can increase the risk of it bonding with the paper and ripping, or being impossible to remove.

For this tutorial I’m using Winsor & Newton brand Colourless Art Masking Fluid:

I’ve also used Misket Liquid Frisket in the past and it also worked really well:

Open your masking fluid only when you’re ready to go to minimize the time it’s exposed to the air. Gently stir it if necessary; try not to stir in too many bubbles! (Some masking fluid, like the Misket pictured above, is coloured to make it more easily to see where it is applied; you might have to stir it to mix the colour into the fluid. Sometimes coloured masking fluid can stain the paper its applied to, but I never had that problem with Misket. Do your own tests and experiments on the paper you’ll be using before trying it on any important art!)

Some people water down their masking fluid, but I never have; watering it down can prolong how long it takes before it dries, and can extend its life, but water it too much and the masking fluid might bond too strongly to the paper, making it difficult or impossible to remove without damaging the paper. Feel free to perform your own experiments if you think watering it down might help. I’ve never watered down my masking fluid, though, and have never had a problem!

Dip your brush/tool into the fluid. If you’re using a brush, try not to dip it down to the ferrule; that is, the metal that holds the bristles. It’s not the end of the world if you do, especially if you’ve well soaped your brush, but it might make it more difficult to remove the latex if it dries into the ferrule.

Now, start painting!


When doing your own experiments try out a wide variety of marks. There are a couple things to keep in mind here: firstly, try not to apply masking fluid too thickly. Even very thinly applied masking fluid will work just fine! The thicker it is, the longer it can take to dry, and also increases the likelihood of it bonding too much with the paper. Secondly be quick; masking fluid dries very quickly. If it dries onto your brush it can clump, causing messes when you try to paint with it, and clog up your brush. Also, you don’t want the masking fluid in your bottle to dry; it can also cause clumps and stringy bits that can make it difficult to get the precision you want.

So, try not to lay it on too thick, and try to paint quickly! if you have to leave it, even for a few seconds, rinse your brush so the latex doesn’t dry onto it. Also, close the cap on your bottle. Seriously, this stuff dries FAST. When you go to add more, re-soap your brush.

Good job, me, using colourless masking fluid… makes it difficult to photograph!

Once you’ve done your masking, rinse your brush thoroughly, and promptly. Depending on how well your brush was soaped and how dry the masking fluid got, this might be easier said than done. 😉 Rinsing it under warm water and using lots of soap can help!

Rinse, rinse, rinse…

Now make sure the masking fluid is thoroughly dry before you continue. This shouldn’t take long at all, but if there were any bits where the masking fluid was pretty thick, it might take longer. Try not to touch it too much until you’re sure so you don’t smudge it!

Now you can do all your fun watercolour stuff! Just paint as normal, adding water, doing gradients, etc., and you don’t have to worry about painting around where you painted the masking fluid; it will repel water, keeping the paper bright beneath it! (Just make sure you don’t use the same water you rinsed your masking fluid into to paint with; the latex in the water can dull your pigments or clog your brushes or cause other problems.)

See how the masking fluid repels the water? Awesome!

I decided to add salt because I couldn’t help myself…

It’s fun watching the salt work its magic over time…!

Try not to get impatient, and try not to use any artificial means to dry things faster. A hair dryer might heat up the latex too much, melting it slightly, making it bond or adhere to the paper. Use your best judgement!

Gently wiping off the salt… I’ll do another tutorial on salt textures in the future!

Now that you’re finished painting, and its completely dry, now comes the fun part… removing the masking fluid!


You can do this by using a soft pencil eraser, though I find it easier to use my finger so I have more control. Starting at the edge of the masking fluid, gently rub it in one direction, away from the edges. It will roll up and start to come away from the paper.

Try not to rub too much on the painted surface itself; you might rub away details or spread some pigment around.

You can also grab at the little rolled up bits and pull it away from the paper, but use caution. Remove the masking fluid carefully and slowly, to try and prevent any tearing or ripping of the paper.

Make sure you remove the masking fluid promptly after you’re done painting. The longer it’s left on the paper the higher the chances of it bonding to it, or being difficult to remove. Every masking fluid brand is different, but do try not to leave masking fluid applied overnight if you can!

Once all the masking fluid is removed, you’re done! Bask in the glory that are clean, white spaces!

Now that you’re done, you can paint back over those areas, use some water to soften the edges, or do whatever  your heart tells you.

Enjoy your newfound power, but try to use it for good!

If you have any further tips or resources, please share them in the comments so others can see them! Also, show us the results of your experiments, I’d love to see. 🙂

Do you have any other watercolour questions or techniques you’d like to see? I’m going to try and do some more watercolour basics tutorials in the future. Let me know!

— Heather

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