In this series we’re looking at different mixed media supplies and telling you a little more about them. This month we’re focussing on a mixed media staple, humble but awesome gesso.
What is gesso?
Gesso is designed to be a ground, primer or preparatory layer for your art substrate. It creates a stable, even surface to work upon, which is opaque and matt, and gives the surface a ‘tooth’ which helps it to grab any paint applied over it and make it adhere better. It was originally used in the preparation of wood panels, which were commonly used as substrates before canvas came into general use at the end of the 16th century. The word gesso means gypsum in Italian, referring to the chalky substance used in the mixture. In mixed media today we use a more modern form of the same product, acrylic gesso, which a mixture of polymer binder (the same stuff you will find in acrylic paints), chalk, and pigment.
Gesso is traditionally white, but nowadays you can get lots of gesso with different pigments. Black is especially useful if you’re using a dark palette or wanting to work over it with metallic or iridescent pigments. Clear gesso is a useful sealer for something like collage, as it makes the surface uniform – for example a layer of clear gesso over collage will prevent the different paper types absorbing the next paint layer at different rates, and therefore giving you a more even and predictable result. It’s also useful for preparing things like scrapbook paper to take mixed media layers, as you can still see the pattern through it. Of course you can also tint your own gesso with any acrylic paint (but note that mixing pigment with clear gesso can make it opaque, depending on the properties of the paint used).
The consistency of gesso varies from brand to brand, some are thicker and some more runny, and some give more texture to the surface than others (sometimes described by artists as being more ‘gritty’ in consistency). What you prefer is really personal choice.
Gesso described as ‘heavy’ will be more like a thick paste and can be scraped through a stencil or used to create sculptural texture. Heavy gesso can be watered down to make it more fluid, although shouldn’t be mixed with too much water, or it will start to lose its permanence.
Why use it for mixed media?
Gesso is super useful for preparing surfaces for mixed media, as well as for traditional canvas painting.
I almost always gesso chipboard and MDF surfaces as the preparation does several things: firstly, it makes the surface less absorbent and therefore you’ll use less paint when you come to add colour, secondly it neutralises the colour of the board so you get a true colour when you add paint and finally it helps to stabilise the surface so it’s more able to take wet media over the top.
In your journal gesso can strengthen thin or brittle paper, such as you might get in a cheap sketchbook, vintage book or junk journal. A coat of gesso will help to stiffen the paper a little too and, as with the chipboard, makes it less absorbent. It will also help prevent colour ‘bleed’ through to the other side of your paper.
The matt finish of gesso can be really useful for mixed media, as it’s much easier to work over with other media than a white acrylic paint (which might have a silk or glossy finish) would be – remember gesso is designed to ‘grab’ the paint applied over it. You can also mix it with your shinier acrylics to make opaque, mattified colours. It’s great for dry brushing, because of the texture and opacity.
Finally, because it’s so opaque it’s great for covering up mistakes like a stray bit of paint or (I speak from experience!) a painty fingerprint!
Top gesso tips!
- Have a separate (cheap) brush for your gesso – because of the gritty texture, gesso isn’t kind to brushes so keep it away from your best ones!
- If you heat set your gesso, do so gently and keep the heat tool moving – it can bubble up if it gets too hot (although that looks cool too – try it!).
- If you want a super smooth surface, use a low grit sandpaper to sand back your gesso. Warning: you may want to stroke it for some time before proceeding with your art! Sanded gesso is lovely and tactile!
- If you haven’t used your gesso for a while, give it a stir or a shake. Some separation is natural but it will effect performance if you don’t re-mix it.
- It’s pronounced ‘jess-o’ in case you were wondering 😉.
I hope that’s been a useful overview of gesso and what it does. This mixed media essential is a little gem that you really can’t do without for your mixed media work!