Hessian
Hessian is inexpensive, but has a very coarse weave and requires a lot of priming. It is liable to become brittle and lifeless in time.
Synthetic fibres
Synthetic fabrics, such as rayon and polyester, are now used in the manufacture of artists’ canvas. These canvases come ready-prepared with acrylic primer and are worth trying out, as they are exceptionally strong and durable, flexible but stable, and resistant to chemical reaction.
Canvas textures
If you use bold, heavy brushstrokes, canvas with a coarsely woven texture is the most suitable. A smooth, finely woven texture is more suited to fine, detailed brushwork. Another consideration is the scale of your painting. A fine-grained canvas is best for small works, as the texture of coarse-grained canvas may be too insistent and detract from the painting.
Ready-primed canvas
Ready-primed canvas comes prepared with either an oil- or an acrylic-based primer. It is better to use an oil-primed canvas for oil painting and leave acrylic-primed ones for acrylic paintings, but you can use an acrylic-primed canvas for oils if you paint thinly and on a small scale.
Canvas may be single- or double-primed. The latter is more expensive; it has a denser surface, but it is less flexible than single-primed canvas.
Canvas weights
Wet the stretched linen canvas and allow it to dry.
The weight of canvas is measured in grams per square metre (gsm) or ounces per square yard (oz). The higher the number, the greater density of threads. Better-grade cotton canvas, known as cotton duck, comes in 410gsm (12oz) and 510gsm (15oz) grades. Lighterweight canvases of between 268gsm (8oz) and 410gsm (12oz) are recommended for practice only.
Ready-prepared supports
You can buy ready-primed and stretched supports which consist of a piece of canvas mounted on a stretcher. These supports are convenient, but are expensive when compared to the cost of stretching, sizing and priming your own canvas.
Popular artist’s canvases
1 Ready-primed cotton-rayon mix
2 Ready-primed cotton duck
3 Ready-primed artist’s linen
4 Superfine artist’s linen
5 Cotton duck
6 Flax canvas
7 Cotton and jute twill
Buying economically
Before buying lengths of canvas, work out how you will divide up the fabric to make as many pictures as possible with the minimum of wastage (canvas rolls come in several widths). When doing your calculations, don’t forget to allow a 50mm (2in) overlap all round each picture for attaching the canvas to the stretcher.
Acrylic and oil don’t mix
Most of the ready-prepared canvases and boards available in art shops are primed for use with oil or acrylic paint. If you paint in acrylics, take care not to buy supports which are prepared specifically for oils. The linseed oil in the primer repels acrylics, and the paint eventually comes away from the support.
Canvas texture
The formal elegance of this abstract painting is enhanced by the subtle texture of the linen canvas, which appears through the thin layers of oil paint.
Pádraig Macmiadhachain
Blue Morning
Oil on canvas
25 × 30cm (10 × 12in)
Overlap
Remember to add a minimum of 50mm (2in) of canvas all round, for when you attach it to the stretcher.
SEE ALSO
| STRETCHING CANVAS | Stretching your own canvas not only offers a saving in cost, but also means that you can prepare a canvas to your own specifications. |
Stretcher bars
Wooden stretcher bars are sold in most art-supply stores and come in different lengths. They have premitred corners with slot-and-tenon joints. The face side of each stretcher bar is bevelled to prevent the inner edge of the stretcher creating ‘ridge’ lines on the canvas. Stretcher bars come in varying widths and thicknesses, depending on the size of support you wish to make. For a work under 60 × 60cm (24 × 24in), use 45 × 16mm (1¾× 5/8in) stretcher bars. For larger works, use 57 × 18mm (2¼ × ¾in) bars.
Wedges
You will also need eight wedges or ‘keys’ for each stretcher. These fit into slots on the inside of each corner of the assembled stretcher; if the canvas sags at a later date, the wedges can be driven in further with a hammer to expand the corners and make the canvas taut again.
Canvas-straining pliers
Canvas-straining pliers are especially useful for stretching ready-primed canvases. They grip the fabric firmly without any risk of tearing, and the lower jaw is bevelled to give good leverage when pulling fabric over a stretcher bar; the correct tension is achieved by lowering the wrist as the canvas passes over the back of the frame.
Other equipment
Use a heavy-duty staple gun and non-rusting staples with a depth of at least 10mm (3/8in) to fix the canvas to the frame. You will also need a rule or tape, a pencil and a pair of scissors to measure and cut out the canvas; a wooden mallet to tap the stretcher bars together; and a T-square to check that the frame is square (or you can use a length of string to ensure that the diagonal measurements between the corners are the same).
