You’ve probably come here wondering what gesso is used for or how to use it properly. That’s not surprising. There’s so much misleading information about what gesso’s role is in acrylic and oil painting. Today you are going to learn what gesso is really made of, some good reasons to use it and the historical significance behind modern day gesso paint as a primer!
- Uses for Gesso
- Acrylic Gesso’s Ingredients & Their Purpose
- How to Thin Gesso
- Where to Find Acrylic Gesso
- Pre-Primed Canvases
- Preparing Your Own Painting Surfaces?
- Is Gesso Necessary?
- A Brief History of Oil-Based Primers
- Acrylic Gesso vs. Oil Primers
- Applying an Oil Primer
Uses for Gesso
No matter what form or brand you are using, gesso is always intended to be used as a stable ground on which to paint upon. It’s a special layer in between your support and your actual painting. It doesn’t matter if you are using acrylics or oil paints, gesso is considered to be a layer of paint that is friendly to paint on top of. We can call this layer a ground or a primer.
Modern-day gesso, the kind you typically find in the art-supply store is made from acrylic paint and should really be called acrylic gesso. Unless specified anything referred to as “gesso” in this article is referring to acrylic gesso.
Acrylic Gesso’s Ingredients & Their Purpose
Acrylic gesso is made of:
- Acrylic Polymer Emulsion (plastic resin suspended in water)
- Titanium Dioxide (White Pigment)
- Calcium Carbonate (Chalk)
The acrylic is really a complex cocktail of chemicals that dry into a plastic film. The titanium dioxide makes the acrylic gesso extremely white and opaque. Finally the calcium carbonate (chalk) is added to make the gesso painting ground have a matte finish, an absorbent surface, and enough tooth (roughness) to pull the paint off the brush.
How to Thin Gesso
Because gesso is water soluble you can thin it with water. For this reason alone acrylic gesso and acrylics in general have become a really popular choice for modern day painters. When thinning gesso add a little but of water at time and mix thoroughly. It’s easy to add too much water and make the gesso too watery.
How Thin Should Your Gesso Be?
I’ve see many gessos come out of the container with perfect consistency, ready to use while other ones were so think they required much thinning. Most artists like gesso to be of a “heavy cream” consistency. Just thin enough to pour but nowhere near the viscosity of water. If your gesso is too thick you will end up getting a brush stroke texture in it.
Where to Find Acrylic Gesso
Any modern container you find that reads “gesso” is of the acrylic gesso variety. It has quickly become the most widely used painting ground for both acrylics and oil paints. It is really inexpensive, super easy to apply, dries very fast and is super easy to clean up. All the major acrylic and oil painting companies make acrylic gesso.
If you’re still unsure about whether or not the container is an acrylic gesso, simply look for the ingredients. Any decent painting product will proudly list the information about what’s in the container.
When you buy a pre-primed canvas or panel it is primed with acrylic gesso. As stated earlier, acrylic gesso has, by far, become the most widely used painting ground on which artists apply paint. Manufacturers often roll or spray apply up to 3 coats of gesso to get even coverage.
This means you don’t need to do a thing to store-bought, pre-primed canvases. They are prepared with gesso already!
Preparing Your Own Painting Surfaces?
Many painters like to stretch their own canvases. Once stretched, you can easily prime a bare canvas with acrylic gesso. Just be sure to use a stiff brush and work quickly.
You can experiment with different thicknesses of gesso, however you’ll find that applying gesso that is the consistency of heavy cream is the preferred thickness used by most artists. Some acrylic gessos come thicker than this in the container and need to be thinned with water.
Once you have the proper consistency all you need to do is apply the gesso to your bare, stretched canvas using a large, stiff bristled brush.
Avoid using those extremely cheap “chip” brushes you can buy at the home improvement stores for around $1.20. Otherwise the brush won’t be the only thing losing its hair throughout the process!
Steps for Gessoing a Canvas:
- Mix gesso to a proper consistency. (use water and only if necessary)
- Quickly lay down a thin coat of gesso working form one side to the other until the canvas is completely covered. The stiffness of the bristles is required to push all the gesso into the crevasses of the canvas fibers.
- Wipe off brush and run brush back and forth across the surface to pop any bubbles and lay the paint down evenly. The brush should be perpendicular to the canvas and just barely touching. Use a crosshatching pattern for optimal evenness.
- Once Dry, lightly sand with sand paper.
- Repeat steps 1-4 until you get the surface you prefer.
It’s tempting to add a ton of gesso all at once but you will get a much better surface if you paint it on in thin layers sanding in between. The more gessoed layers you complete the smoother the canvas becomes. Repeat the process of priming + sanding enough and you’ll end up with a surface so smooth you will no longer be able to tell that the gesso is supported by canvas! But if you want a surface that’s completely smooth you should just work on a panel.
It’s tempting to sand the gesso once it’s dry to the touch. You’re best letting the gesso dry overnight. Acrylic paints such as acrylic gesso can be dry to the touch but will be gummy if you try to sand them. Just be patient!
Priming a Panel With Gesso
If you want to paint on a panel you’ll be ready to paint in no time using acrylic gesso. One or two coats is all you need to prepare the surface for painting. Please note that it’s almost impossible to retain a smooth surface if you are applying the gesso with a brush.
For the smoothest results you’ll want to use a paint roller with a smooth nap and for even smoother results you can spray apply your gesso!
Before you grab one of those large paint rollers designed for painting walls think again. Most of those roller tube are made with a ¼ inch or 3/8 inch nap. This will result in an orange peel texture on your panel.
Take a close look at the painted walls in your home under good lighting and you’ll see the texture I’m referring to. For the smoothest result, priming a panel, use a 6 inch foam roller that has no nap at all.
You may want to lightly sand the panel to make sure the gesso has enough tooth to grab onto. This is especially the case in hard, super-smooth surfaces found in some Masonite boards and tempered hardboards.
Steps for Gessoing a Panel:
- Lightly sand the panel’s surface. (200+ grit or else the scratches will become apparent)
- Clean dust off surface with damp, lint-free cloth.
- Mix gesso to a proper consistency. (use water and only if necessary)
- Roll gesso on evenly, while flat on a table.
- Once Dry, lightly sand with sand paper.
- Repeat steps 1-4 one more time for a bright white surface.
Troubleshooting Your Priming Job
Here’s some common problems that can arise when using a brush to apply gesso to a canvas.
|Hairs in the ground||
|Lumps & brush strokes||
|Gummy when sanding||
|Canvas texture shows too much||
Is Gesso Necessary?
Whether or not it is necessary to paint upon a surface primed with gesso depends upon which kind of paint you are creating with. If you are using acrylic paints you do not need to use gesso. The acrylic paint will not harm the raw canvas in anyway. Raw canvas is, however really absorbent and not too ideal for most brushing styles of painters. Painting on raw canvas is like painting on a table cloth. Raw canvas will soak up all the liquid of the paint and is most suitable for staining rather than pushing the paint around and blending.
So acrylic painters don’t have to use gesso but will probably want to.
It is absolutely necessary for oil painters to create some kind of barrier between their oil paints and the raw canvas material. If oil comes into contact with raw canvas the canvas will become brittle with time and eventually fall apart. Many artists refer to this as canvas rot.
Many oil painters overcome this propensity of oil paints to rot a canvas by priming their canvas with acrylic gesso. The acrylic gesso creates a barrier between the actual canvas and the oil paints and oil painting mediums.
Now you might be thinking… Oil painting has been around for hundreds of years and acrylics have only been commercially available since the 1950s… how did oil painters protect their canvases from deterioration prior to the invention of acrylic gesso?
A Brief History of Oil-Based Primers
Acrylic gesso derives its name from the Italian word for “chalk” or “plaster” and isn’t really the true gesso at all in a historical sense. This authentic gesso used by classical Italian painters was made from an animal binder such as rabbit skin glue and a variety of whiting agents such as chalk, plaster, or even marble dust.
Many of these old practices for preparing canvases and panels are still employed today by the world’s leading oil painters and diehard hobbyists.
If you are shopping for high-end canvas to paint on you’ll invariably come across oil primed canvas. These canvases are often made of linen and sometimes cotton. Oil primed canvases are not primed with acrylic gesso. They are primed with an oil based formula. Think oil primer like acrylic gesso containing the titanium dioxide (white pigment) and calcium carbonate (chalk) but with the binder being an oil medium instead of an acrylic resin.
Many of the oil paint manufacturers are now selling oil primer and their recipes do vary. Many of them introduce an alkyd resin into the oil-binder part of the primer as a drying agent.
Sizing a Canvas
If you are working with an oil primer you should first size your canvas to protect the oil-based primer from coming into direct contact with the raw canvas fibers. Traditionally a hide glue made from rabbit skin was used to do this. I made this stuff from scratch in college and can tell you that it stinks to high hell.
Because we don’t want to hurt any adorable bunnies and because conservators recommend more flexible, modern substitutes such as PVA, unless you’re an art forger there really isn’t much use for rabbit skin glue anymore. Use a quality PVA size to seal and protect your canvas prior to using an oil primer.
Acrylic Gesso vs. Oil Primers
The internet seems to be fertile ground for hobbyist painters whom love arguing minutia. You can spend hours, days, or even weeks reading all the big-headed painters’ recommendations on how one old master’s method is the only way all other methods are bad. (here’s looking at you wetcanvas). You can get scared and confused about fat-over-lean principles, so scared and confused that you actually spend all of your time reading stupid forums instead of actually painting!
Don’t worry about this stuff too much. My recommendation is to learn a little as you go and for God’s sake don’t get hung up on the minutia. Just keep painting, and studying with the best instructors you can find. Learning about the materials IS important but so is getting better at the skill of painting.
Personally, I like the feel of an oil-primed surface beneath my brushes and acrylic gesso feels a little too absorbent for my painting methods. Even though I love working on oil-primed linen canvases doesn’t mean I would recommend this setup for a beginner painter. My setup is really expensive compared to acrylic gesso on cotton canvas and requires way more preparation, experience and drying time.
Applying an Oil Primer
While the focus of this article is aimed at modern-day acrylic gesso I thought I would mention some helpful techniques for applying oil based primers as they can really be applied easily with a brush like you would with acrylic gesso. Check out the video below which explains how to trowel on oil primer and level out the surface. Again, if you are still learning how to paint, don’t bother with all of this. Just stick to pre-primed canvases for now.
- Acrylic gesso, although not the real gesso used by our oil painting ancestors, is a great ground to paint on top of with any painting medium. While usually white in color, companies have gotten creative with their gessos and are now offering black gesso, clear gesso, etc… You can even tint the gesso slightly with an acrylic paint if you’d rather work on a ground that is not pure white.
- If you’re just starting out, don’t mess with complicated and expensive oil painting primers, just stick to a quality acrylic gesso and spend your efforts improving your painting skills.
- You can make a canvas smoother by applying subsequent layers of gesso, letting each layer dry overnight and lightly sanding in between applications.
- Gesso can be thinned with water to a desired consistency and can be brushed, rolled, or sprayed. Because it is water soluble cleanup is a snap!
- Because acrylic products dry notoriously fast, you must work quickly and complete the priming process in one continuous timeframe.
I’ll leave you with a 2 minute video from Liquitex, manufacturers of all different kinds of gessos / grounds on which to paint on!