There are four basic elements to the structure of an oil painting: (1) the support (e.g., canvas, wood, copper or aluminum panel), (2) the size layer, (3) the ground layer and then (4) the oil paint layers.
For convenience, many artists purchase brand-name or generic supports from art suppliers with the size and grounds already applied to the canvas or panel.
Artists who are more quality conscious might buy rolls of canvas pre-primed (with the size and grounds applied), and then cut out pieces that they then staple or tack onto their own stretchers bars or glue onto their own panels.
Still others want full control over what they paint on. They might purchase fine quality linen that is completely raw and then size and prime it themselves before stretching it or gluing it onto panels. Some artists even avoid linen altogether. They prepare their own rigid supports, apply the size and grounds themselves, and then paint directly on them.
Even artists who buy prepared supports or buy pre-primed linen should have some awareness about what type of size and ground has been used — that is, if they care at all about the longevity of their work.
What I paint on now is lead-primed linen canvas glued and tacked to rigid panels with basswood bracing around the edges, or polyester canvas glued to honeycomb aluminum or ACM panels. (See our page on supports for more information)
If I were to want to paint on stretched canvas, I would size it with one of Golden’s current recommendation for sizing products or two coats of Gamblin’s PVA Size, and then I would prime it with white lead bound with linseed oil. It would require re-stretching at least once during this process, and again later.
Those artists who purchase pre-primed linen should determine the nature of the ground used.
If the painting you intend to paint is important to you, my suggestion is NOT to paint it on a canvas that has zinc oxide in its oil priming.
Where permanence and longevity are concerned, traditional oil grounds are the very best for use with rigid supports or canvas glued to them.
Artists who purchase prepared supports may want to add another layer of ground on their own. If you do so, allow plenty of time for the new ground layer to cure, even with acrylic grounds, for optimal performance and longevity. Water escapes slowly from water-based grounds/primers, and there are other ingredients in acrylic grounds that migrate to the surface with the water but do not evaporate, thus they end up on the surface. It’s a good idea to clean the surface of them before painting on these grounds with oil paints.
Definitions and Types of Grounds
Ground: a priming layer applied to the support on top of the size. Its main purpose is to seal and prepare the surface to accept subsequent layers of oil paint, allowing for proper adhesion.
Other benefits of grounds: they counteract the uneven absorbency of supports; they help buffer the effects of humidity on supports; they can make the paint application easier and consistent; they can be toned for aesthetic effects; and when the grounds are white, they can reduce the visual distortions from paint that becomes transparent over time.
Priming: the act of applying a ground.
Gesso: a traditional ground made of melted animal collagen glue mixed with a white pigment such as calcium carbonate, calcium sulfate, or gypsum. It should be applied only to rigid supports.
Traditional Oil Ground: a priming layer, white or light grey usually, with linseed oil or alkyd resin as the binder. It is quick drying and lean. It remains the very best as far as long-term performance and durability are concerned.
The best oil primer is white lead in linseed oil, with perhaps a minor addition of calcium carbonate. Together these ingredients make a leaner ground than any of the paints that will go over it. “Leaner” means it has a lower percentage of oil in it than any of the oil paints you will be applying on top, in perfect accord with the fat-over-lean dictum.
Acrylic Ground: A modern alternative to traditional oil grounds for priming. A good acrylic ground has
sufficient acrylic levels to yield excellent flexibility, while also having sufficient pigment levels to create a favorable level of absorbency and opacity. There should be enough water to ensure proper shrinkage to tighten a stretched canvas, yet be resistant to cracking when flexed. (Golden offers a line on acrylic grounds).
Virgil notes: manufacturers often incorrectly acrylic grounds as”gesso,” which creates confusion. Real gesso is not flexible enough to be a good ground on stretched canvas, but acrylic grounds are. Since they are different materials with different properties and applications, they should not be called by the same name.
Fredrix is one of the better brands of pre-stretched canvases. Their acrylic ground is a heat-set acrylic, which is probably as good as an acrylic ground can be.
Advice for Priming
Ground layers should be applied evenly and thinly. Sanding between coats can be done to produce a smooth finish.
According to MITRA, oil, acrylic dispersion, and alkyd grounds can be applied to either fabric or rigid supports. But traditional gesso, which is relatively brittle, should only be applied to rigid supports; flexible supports with gesso as the ground are more susceptible to cracking and other problems in response to changes in the environment.
The very best situation for oil paintings is a lead ground bound with linseed oil, because it imparts extra durability, film strength and flexibility to all the oil paints applied on top of it. If the white paint used is also lead white, so much the better, as far as long-term performance is concerned.
Gamblin Ground is NOT water-based and requires adequate wait time before paint layers are applied.
Priming Canvas Supports:
Trying to prime stretched canvases with traditional gesso is a bad idea, because it is not flexible. Real gesso is a good ground for rigid wood panels, but not for stretched textiles. Gesso is not a suitable ground for stretched canvas because it lacks sufficient flexibility
Historically, painters experimented with adding linseed oil, honey, and perhaps other ingredients to glue-chalk gesso to make it more flexible for use as a ground on canvas. Those experiments generally did not work out well, and the practices were discontinued after it was discovered that white lead in linseed oil was a better ground than glue-chalk gesso for paintings on stretched canvas.
Priming ACM Panels:
ACM panels should be primed first with an acrylic or alkyd primer that has been tested for adhesion on that surface. Not every acrylic or alkyd primer may be suitable for use on ACM. Golden has tested their acrylic primers on ACM, and Natural Pigments has tested Rublev Colours Lead Alkyd Ground on ACM.
Priming Copper Panels:
Historically, oil paintings on copper have been done using an oil ground of white lead in linseed oil or painted on in oils directly on the copper. These paintings have generally held up quite well. I would be leery of applying any water-based ground such as acrylic to copper, because it has no long-term history to assure me of its soundness. Thus it’s essentially a gamble with the future condition of the painting at stake, and unnecessary.
Here are some valuable resources from reliable sources:
Adhesives and Sizes Advisory by MITRA (Material Information and Technical Resources for Artists) — PDF document
Grounds and Primers by MITRA — PDF document
Grounds for wood panels — This Natural Pigments article provides recipes for sizes and grounds, and step-by-step instructions on how to prepare and apply gesso to wood panels.
Emulsion grounds — another Natural Pigments article on creating and applying emulsion grounds, which typically consist of an emulsifying adhesive, such as animal collagen glue and vegetable oil with chalk and lead white. They can be applied to all kinds of supports.
Preparing a Canvas for Oil Painting (Advice on Sizes and Grounds from Gamblin)
Preparing a Painting Support (Advice for Sizing and Priming from Golden)