How To Make An Acrylic Painting Waterproof

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Acrylic paints are great for painting many things, even objects that will be stored outside, like a birdhouse.

While the paint might stick to your painting surface, if it’s exposed to water before it’s completely dry, the paint will wash off.

This can end up leaving your painting job with missing pieces of paint, and ultimately destroying your painting.

What Is Acrylic Paint?

Acrylic paint is pigment mixed in acrylic polymer emulsion.

But what is acrylic polymer emulsion you might ask.

This is just a fancy term for it being a water-based paint. Acrylic polymer emulsion is also what makes the acrylic paint dry so quickly. Since this paint is water-based, the water will evaporate quickly, which leads to a faster paint drying time.

Why Should I Waterproof My Painting?

Even though acrylic paints will dry quickly and are known for being a “strong” paint that will practically stick to anything, if you don’t waterproof it before it’s dry, your hard work could instantly be destroyed due to a glass of water accidentally spilling on it or even from some raindrops if you’re working outside.

While acrylics are a tough paint, meaning that once they are dry water can’t really harm them, it’s still good to waterproof your painting.

This can be done with a varnish, which is a special type of acrylic gloss.

Why Would Varnishing Help?

Varnishing helps protect your painting by putting a sealing layer over your work.

This means that if you varnish a painting and then put it outside or near water, you don’t have to worry about it being damaged.

Another advantage of varnishing your painting is that if it’s exposed to a lot of light, it can help protect it from any possible fading.

varnish ruin brush

What Makes The Varnish Water-Resistant?

The makeup of the varnish is amazing.

With only a few ingredients, varnish has the ability to make anything waterproof.

What are these amazing ingredients?

Usually, varnish is made up of the following:

  • Resin
  • Solvent
  • Oil
  • Driers

These then can branch out to specific types, depending on the kind of varnish you’re using.

These five ingredients are a lifesaver for your painting job.

How Do I Varnish My Painting?

Thankfully, it’s not difficult to do, but it does require a few steps, so make sure you have some time on hand before attempting to varnish.

However, the right varnishing steps depend on what kind of surface you’re painting on.

canvas painting

Waterproofing Acrylic On Canvas

Canvas is often the most popular acrylic painting surface.

Before painting on your canvas, you can prime your surface (usually gesso), although it’s not required.

This would just help seal your painting even more. But even if you don’t, using a varnish (such as polymer) will still help protect it.

A variety of acrylic varnishes are available from popular online retailers like DickBlick.

Waterproofing Acrylic On Metal

Metal is often painted with acrylic paint because acrylics can stick well to it.

Doorknobs, lamp bases, and even picture frames can be perfectly painted with acrylics.

Poly Varnish is also great for this type as well. One coat of it on a metal surface usually gets the job done.

Waterproofing Acrylic On Wood

If you’ve just finished painting a majestic animal scene on a pallet, you probably wouldn’t be too happy if all your hard work suddenly washed away.

So, after painting on wood, you can varnish it with a polymer varnish, but this time you’re going to need two coats.

You should wait about a day in between before applying the two so each coat can fully dry.

Waterproofing Acrylic On Masonite

Masonite is a type of wood (incredibly thin compression of wood fibers).

Just like the others above, once you finish painting on Masonite you can use a polymer varnish to seal it.

One coat is usually enough.

Waterproofing Acrylic On MDF

Yet another type of wood, MDF is similar to Masonite in its thinness, but it does have a hard surface.

Usually MDF is used for decorative elements because it can be cut and designed easily.

Before painting on this type of surface, be sure to prime it with something like gesso, so the paint sticks and the varnish stays.

Poly Varnish is also great for this and you only need to apply about one coat.

Waterproofing Acrylic On Plastic

If you plan to paint acrylics on plastic, do know that often it will require a few coats of paint to fully cover it.

Once done though, you can varnish the surface with a quick coat.

Waterproofing Acrylic On Glass

Glass is a unique surface to be working with, but it can easily be varnished.

One way is to just leave the glass alone for about 3 weeks after putting a seal of varnish on.

The other way to seal acrylic paint on glass is to put it in the oven.

You can turn the oven on to about 350 degrees, and then let the glass “bake” for about 30-45 minutes.

Be aware though that this time depends on the type of acrylic paint you used, so be sure you know what it is before putting the glass in the oven.

While this second choice might seem like a quicker drying method, it can also cause some unpleasant fumes.

Baking the glass with the varnish will create fumes that will fill and coat your oven.

You’ll need to clean and air it out after baking the glass if you use this choice.

Both ways of sealing glass are time-consuming in their own way, so decide if you want to wait for a few weeks without having to do much, or if you want your glass painting as quickly as possible, but will end up having to meticulously clean afterwards.

Be sure to check out this in-depth guide on using acrylics and glass for further guidance.

Do I Need Special Tools To Apply The Varnish?

There aren’t any required tools, but a paintbrush that is often cited to be good for applying varnish is a foam poly brush.

This type of brush is preferred because the foam can soak up the varnish and help apply it evenly on your surface.

Be careful though that you paint even strokes and don’t rest the brush for too long on a specific area, as this will show through the varnish.

Also, don’t keep your hand on the painting to keep it steady while applying it, as your fingerprints can damage the varnish.

After all your hard work painting something, the last thing you probably want is for someone to not notice the fantastic job you did, but rather the fingerprints everywhere.

So while no special tools are needed, you do need to have something under your painting when applying the varnish, which if you don’t, could cause damage to that surface.

varnish ruin brush

Will The Varnish Ruin My Brush?

No, not if you clean properly.

Acrylic paint varnishes usually just require you to clean the brush with water and dry it off. Your brush will be ruined though if you don’t, so be sure to wash it right after using it.

Another cool thing though about acrylic paint varnishes is that they can also come as a spray.

If you decide that using a brush isn’t for you, then a varnish spray is a good choice. However, if you do use a spray varnish, you’ll have to apply a few layers to get a full coat.

Types Of Varnishes For Acrylics

Acrylics do come in different types of varnishes.

While gloss is often the go-to varnish, there’s also a matte and satin varnish.

A matte varnish is a little shinier, while a satin varnish will protect it from the sun as well as applying a very shiny coat.

Something To Consider

While you don’t need to prime your acrylic painting surface, it’s often a good idea to do so, especially when working with a varnish.

This way the paint not only stays neatly on the surface, but it can also add to the varnish’s shine.

Following the steps and ideas above will not only help you save your piece of art from being damaged by water, but will add an extra shine to your art piece.