Acrylic Painting Mediums (to Prime and Finish your work!)


Hi friends! It’s a blustery day out there! I’m happy to be home from work, and don’t plan on leaving my house anymore today! So here’s a new blog post for you! If you watched my last video on Tuesday(click here!), I gave an introduction to using acrylic mediums.  These mediums are all designed to help you work with the paint in various ways in order to achieve your desired effects.  But the world of “mediums” is much larger than that!  What about products to help you paint on virtually any surface, or a finishing medium to protect your final masterpiece?

That’s where gesso and varnish come in!  Acrylic gesso is a primer used to “roughen up” (also known as adding tooth) super smooth surfaces, giving your paint something to stick to!  It also strengthens and seals whatever you’re using it on, so your chosen surface can handle the acrylic paint!  Varnish, on the other hand, provides a finishing layer over your painting, protecting it from the environment, yucky fingerprints, and even dust!  I’ll go into these two things a bit more…

Acrylic Gesso

Acrylic gesso traditionally comes as a white, VERY opaque, grainy-feeling product with the consistency of a soft body (or fluid) paint.  The whiteness is from it’s inclusion of Titanium White into the mixture, but you can also buy it in clear or black versions.  One coat is usually enough if your goal is to simply prime a surface, or to cover up an old painting for re-painting purposes.  Just like all acrylic mediums, gesso is flexible and non-yellowing throughout time and can be mixed with other acrylic paint colours to give yourself your own custom gesso colour!

Do I have to use gesso??

If you’re painting on primed stretched canvas (the kind you can buy already stretched around a frame from art supply stores, and they’re all white…you get one guess as to why they’re all white!), you do not need to gesso, because – you guessed it – they’ve already been coated with gesso!  The more expensive brands of canvas even state that they’re “triple-primed” meaning that they have three coats of gesso over the cotton or linen canvas, so you’re good to go.

If you’re painting on anything else other than heavy watercolour paper or clayboard (like the ones from Ampersand), you’ll probably want to gesso your surface.  Some woods acrylic paint can grab onto, but for most it’s probably best to gesso.  If you want to keep the pretty grain of the wood visible, then simply use clear gesso!

Clear gesso is also awesome to use in mixed media works.  It’s a perfect tooth for pastels to grab onto, so you could do a layer in acrylics, clear gesso over, then do some detail work in pastel.  Alternatively clear gesso is also handy if you’re doing a basic layer with watercolour, then want to use acrylics over top, but are worried about the water used with acrylics picking up the watercolour paint.  Just lay down a quick layer of clear gesso over your watercolour, and you’re good to go with no worries!


Varnish is for the last stage of painting, when you want to seal your work to protect it!  Varnish protects the paint colours from UV light (preventing fading) and protects the paint surface from the elements like dirt and dust.  Varnishes also give an added bonus of increasing the depth and colour saturation of your painting! If a painting that is varnished starts to collect dust or dirt on it surface, a clean damp cloth can be gently wiped over the painting without fear of damaging the paint film.

Varnishes come in two kinds: removable and permanent.  Removable varnishes can be dissolved with mineral spirits or turpentine, taking all the collected dirt and dust with it, then a fresh layer can be applied to replace it (we’re talking after many many years here!).  A good idea with removable varnish is to coat your painting with an “isolation layer” – a thin layer of gel medium – to separate the paint from the varnish.  This way many many years into the future if the painting needs to be cleaned the varnish can be removed without fear of damaging the paint layer.

Varnishes, like mediums, come in different finishes.  If you don’t want any shine to your painting you can choose a matte varnish, or you can pick good old gloss for added depth to your painting, it’s totally up to you!

How long after finishing a painting can I varnish?

With acrylic paintings, the general recommendation is 3 days – 2 weeks, depending on the thickness of your paint application.  I always wait at LEAST two weeks, just to be safe.  You don’t want to seal up paint that’s not fully cured! This can lead to the eventual degradation of your masterpiece!  Good things come to those who wait, remember? 😉

Hopefully this helps you!  Acrylic mediums are awesome tools to help you achieve the painting effects that you want, you just have to take the time to get to know them! 🙂

I’ll be uploading a new speedpaint tomorrow!  I hope to see you then!  Stay warm everyone!!


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