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How to Use Masking Fluid?

how to use masking fluid

Knowing how to use masking fluid will allow you to create brighter and sharper whites when using watercolors. If you have been using watercolors for a while, then you probably know that it is impossible to paint completely white spaces. The white color in the watercolor palette is only there to lighten the other colors.

Masking fluid is a latex-based “paint” that you can use to prevent the watercolors from penetrating the paper. Using a masking fluid will allow you to create negative spaces and sharper edges. If you learn how to use this product properly, you can make your watercolor paintings significantly better.

Step-by-Step Guide

What to prepare:

  • Masking fluid
  • A small dish for the masking fluid
  • A small bowl of soapy water (if you will be using a brush)
  • Applicator like a brush
  • A vinyl eraser (for removing the masking fluid)

Detailed Steps:

remove the masking fluid

Step 1 – Prepare your brush

One way to know how to use masking fluid is to use the same brushes you would with your watercolors. However, you should not dip the brushes directly into the masking fluid. This would ruin the bristles.

To prevent the masking fluid from ruining your brush, you should dip it into the dish with soapy water. After a couple of applications, dip and swirl the brush in soapy water to keep the bristles from gumming up.

Step 2 – Plan your painting thoroughly

You will only be getting one shot at using masking fluid. If you made a mistake and you already painted over it, then you have no other choice but to redo the entire thing. Make sure to plan where you will be masking your painting, and sketch your painting beforehand so you can apply the masking fluid accurately.

Step 3 – Dilute the masking fluid if needed

Most of the time, masking fluid can be too thick when used straight out of the bottle. I usually dilute the masking fluid a bit using some water to thin the product a bit. Thinner masking fluid is ideal for painting thin lines and detailed shapes.

Step 4 – Apply the masking fluid

Dip the prepared brushes into the masking fluid and then apply it to the paper. Ideally, you should apply the masking fluid before painting with the other colors. You need to sketch your drawing first and then apply the masking fluid over the places that you want to keep white.

Step 5 – Apply your watercolors as normal

Once the masking fluid has dried, which only takes a couple of minutes, you will find that the masking fluid works just like tape. However, you can also apply it in whatever kind of shape that you can imagine. This is even if you accidentally paint over the masked area without placing paint on the paper.

Step 6 – Remove the masking fluid

Ideally, you should remove masking fluid from the paper after one week, up to three weeks tops. If you don’t, the mask will turn an ugly yellow color.

To remove the masking fluid, grab a regular vinyl eraser and gently rub it. You need to be careful when you are removing the masking fluid as you might rip the paper.

Why Should You Use Masking Fluid?

dilute the masking fluid

Masking fluid is the best way to mask off small and complicated shapes when making watercolor paintings. Masking tape will not be that helpful when using watercolors because the colors will still seep into the paper, and the water will also dissolve the adhesive of the tape.

Masking fluid will prevent watercolors from touching the paper underneath, making it the most ideal masking product.

Other Tools for Applying the Masking Fluid

Although paintbrushes are the preferred tools for applying masking fluid, there are other tools that you can use, including:

  • Dip pens (for sharp lines)
  • Color shapers
  • Toothbrushes
  • Stencil brushes
  • Rolled bits of paper

And more…

Tips for Using Masking Fluid

Don’t apply the masking fluid while the paper is wet – If you like using the wet paper method when making watercolor paintings, you should not apply the masking fluid while the paper is wet. This will prevent the masking fluid from adhering to the paper.

Soften the edges – One problem with masking fluid is that it often leaves sharp edges, which is a stark contrast to soft watercolor paintings. However, you can soften these edges easily. Use a damp brush to lift the pigment off the edges, giving them a softer look.

Use different techniques – You can use masking fluid like how you would watercolors, and as such, you can use other brushes or items to apply the mask. Aside from different tools, you can also use other brush techniques.


Masking fluid is one of the best tools that you can use to create dazzling works of art. However, it does take a bit of practice to learn how to use masking fluid effectively. Once you know how masking fluid works, you will be able to create dazzling whites on your watercolor paintings with hardly any effort at all.