various types of primer, each with its different characteristics. It is important to choose the right one for your needs, as it affects the way paint is ‘pulled’ from the brush, and its finished appearance. For example, if you like to work on a smooth surface, you will require a different ground to someone who prefers a slightly textured, dryish surface that gives the paint a matt, chalky appearance.
In addition, it is vital that you select the right type of primer for your chosen support. Canvas expands and contracts, and thus requires a flexible ground; therefore an inflexible gesso ground is not suitable.
The ground should be absorbent enough to provide a key for the paint, but not so absorbent that it sucks oil from it – a common cause of sinking (the appearance of dull patches of paint across the canvas).
Oil primer
The traditional, and best, primer for oil painting, particularly on stretched canvas, is oil-based lead-white primer. This is flexible, stretching and contracting with the canvas on changes in temperature and humidity. It dries to form a durable base, which will not absorb too much oil from the paint.
Applying oil primer
Lead-white primer is quite stiff, and should be let down slightly with turpentine so that it can be brushed out easily. Apply an even coat as thinly as possible, brushing it in well (1). Finish off with a long smoothing stroke in line with the weave of the cloth (2). You should leave this first coat to dry for two days before applying a second coat.
The primed canvas should either be used while touch-dry (within a week or two) or be left to cure for four to six months before use. If paint is applied between these times, the primer sucks oil from the paint, leaving it underbound and with insufficient adhesion to the support.
Yellowing
The linseed oil in which lead white is ground turns the priming coat yellow if the primed support is stored away from the light for any length of time. The whiteness is restored upon exposure to sunlight.
Alkyd primer
This is a valid alternative to oil primer, as it is flexible, non-yellowing and fast-drying; each coat can be overpainted after 24 hours. Dilute alkyd primer with white (mineral) spirit to the required consistency.
Acrylic primer
Acrylic primer is flexible, durable, water-thinnable, fast-drying and inexpensive. It can be used to prime canvas, board, paper and other surfaces, and can be applied directly to the support without the need of an isolating layer of size. It dries in a few hours.
Acrylic primer is the ideal surface for acrylic paints, providing a bright undercoat which brings out the vividness of the colours and gives added luminosity to thin washes. It can also be used with oil paints on rigid supports, but this is not recommended for canvas painting, except in a thin layer: acrylic is more flexible than oil, and the different tensions may eventually lead to cracking of the paint surface.
Acrylic primer is often referred to as acrylic gesso, a confusing term as it is not a gesso at all; traditional gesso is prepared with animal glue and chalk, and is very absorbent.
Applying acrylic primer
Work from the edges and apply the primer quickly in sections. Use a large brush or a paint roller, and keep the working edge moving, as acrylic primer dries quickly. Leave to dry for a few hours. The second coat should be applied at right angles to the first.
When priming board, you can apply as many as five coats for greater whiteness and opacity. For a really smooth finish, thin the last coat with a little water. For a textured finish, impress a piece of canvas (or any textured fabric) into the final coat of primer while it is still damp. Pull it away, then let the panel dry.
Checking primers
Commercially produced primers may become hard if kept on the shelf for too long, so it is wise to shake a tin before buying it to make sure that the contents are still liquid.
Applying primer:
• Apply it in several thin coats – a thin coat is pliable while a thick coat is likely to crack and may even flake off the support.
• Cover the entire surface evenly. Don’t go back over brushstrokes.
• Make sure that each coat is touch-dry before any subsequent coat is applied, and also before starting to paint.
(1) Applying a thin, even coat
(2) Finishing off
Acrylic over glue
Never use acrylic primer over animal-glue size, as it will prevent the paint from adhering properly to the support.
Paint rollers
It is a good idea to use a paint roller to apply acrylic primer. A roller keeps the paint moving and delivers an even coat; for small supports, use a small radiator roller.
Working sequence
Work in sections; leave primer to dry between coats; apply subsequent coats at right angles.
Emulsion paint
An economical primer, often used by students, is ordinary matt household paint, which provides a sympathetic, semi-absorbent ground. However, household paint should only be used on rigid supports, and not on stretched canvas. Use only good-quality paint; cheap emulsions have a limited life span.
Using primer creatively
The lovely, matt, airy quality of Fred Cuming’s paint is due in part to the ground he works on. After many years of painting, Cuming still finds the best primer is a good-quality, matt, white undercoat. When the primer is thoroughly dry, he applies a thin layer of linseed oil to the surface and wipes it off immediately, leaving just a trace of oil. When this is dry – after two weeks – the resulting surface provides a sound key for the paint, and prevents it sinking.
Fred Cuming
Bathers – Cap Ferrett
Oil on panel
60 × 50cm (24 × 20in)
Brian Sinfield Gallery, Burford
Textured finish
