Oil paint can be an amazing substance to work with, from creating quick sketches outside to photo-realistic portraits. Because oil paints take a long time to dry, they give you the flexibility to be able to tweak, alter, soften and blend resulting in lovely muted, smokey subtle paintings.
If you decide that you’d like to give oils a go, then my recommendation would be to start with a pre-sized, pre-primed ready-made canvas to paint on.
Well, the “oil” in the paint can create a few issues over time you should be aware of.
We’ve all heard of “fat over lean” and paintings cracking but don’t be scared…
It’s really very simple, below gives you a quick overview of the best preparation needed for a canvas, when working with oils.
Oil can make your painting brittle
Over time as oil oxidizes it can make the canvas fibres brittle and more delicate. If you apply a coat of “size” to a raw canvas it acts as a seal between the oil in the paint and the canvas.
So what are the options?
Ready-Made Canvas from the Art Store
Just to clarify, a pre-sized and pre-primed ready-made canvas means you’re good to go, you don’t need to do any more to the surface, you can just get painting.
However, you can now buy various stages of preparation of a ready-made canvas:
1. A canvas that has been pre-sized but not primed – With this you can either paint straight on top of it, or my recommendation would be to apply a couple of coats of gesso to give a better painting surface. This option is probably for the more experienced painter as it allows you to bespoke your primer (Gesso) application.
2. A canvas that has been pre-sized and pre-primed with an Oil paint primer, also known as a traditional Oil Gesso – This is how a traditional canvas would have been prepared and the Oil primer allows an oil ground and oil paint on top of it. You cannot apply an acrylic ground to this surface.
3. A canvas that has been pre-sized and pre-primed with an Acrylic paint primer, also known as an Acrylic Gesso – This is a modern alternative and allows you to paint an acrylic coloured ground and a thin acrylic under-painting before moving onto an oil paint layer. Why would you want to do this? Speed and convenience as acrylics dry so much faster, some painters like blocking the bones of the painting with acrylics first.
N.B. You can paint thin applications of acrylics under oil but you cannot paint acrylics on top of oil paint.
Raw Canvas bought in a Roll (normally then stretched onto stretcher bars to create a taut painting surface)
You can, of course, buy raw canvas and prepare it yourself. This is more cost effective but time-consuming.
The Size Layer
- PVA Glue – As a student with no money I used to use PVA craft glue for tester pieces. It is cheap, forms a barrier and is great to practice with kids. Cheaper PVA is not the ideal choice as it can become very brittle and unstable over time but you can now get PVA that has been specifically designed for artists.
- Acrylic Size – To replicate traditional Rabbit Skin Glue, you can use a combination of an acrylic polymer called GAC400 and GAC 100. GAC400 must be applied to raw canvas and will stiffen the fibres first, before then applying GAC100 which is a Multi-Purpose Acrylic Polymer sealer. Applying two coats of GAC 100 before the primer/Gesso layer will reduce linseed oil penetrating into the canvas fibres.
- Rabbit Skin Glue – Yes you read that correctly, it’s one of the most traditional ways of sizing a canvas and is made by mixing dry glue with water and gently mixing together. It’s one of the worst smells I’ve ever experienced. It’s a laborious and smelly process as you have to apply when warm but for creating a drum-tight canvas, it’s great.
However, it is hygroscopic, meaning it will always be water soluble and can absorb water over time. High humidity will re-introduce water into the rabbit skin glue, causing it to soften or swell up. If the painting is in an environment with changing humidity this constant swelling and drying of the film and can become brittle and cause cracking of the final paint layer.
Pro Tip: Cotton canvas does not absorb the size as well as linen and will need a stiffer brush and more working into the surface.
The Primer Layer
- Oil Gesso – This is a traditional primer and allows an oil ground and oil paint on top of it. You cannot apply an acrylic ground to this surface.
- Acrylic Gesso – This is a modern alternative primer and allows you to paint an acrylic ground and a thin acrylic under-painting before moving onto an oil paint layer.
You can read more about how to apply an Acrylic Gesso here
To begin painting with oils black and white is often a good place to start, here is part 1 in a 5 part series of my approach to painting a classical oil portrait in black & white
You might also like:
1. 8 tips to help you make a killer Bespoke Canvas
2. Getting Started: How a prepared Canvas can drastically improve your painting – An Old Master technique to rapidly improve your paintings