Sonia has visited the guild several times and given demonstrations as varied as; techniques of the masters, portraits, and impressions of flowers.
This time was rather different as she gave a practical demonstration of the making and preparation of canvases.
For this demonstration Sonia used a stretcher which she had assembled from a flatpack kit which required only the use of a hammer.
Sonia prefers to use artist grade linen for her 'canvases' rather than the cheaper and inferior cotton/linen mix. This can be purchased in rolls, typically 10 metres in length and widths of 1 or 1.4 metres. This is the most economical way of buying linen for artists, and is particularly suitable for art groups where the cost can be shared. It is possible to buy offcuts at some art suppliers but the quality can be more variable and it is recommended to wash and dry the material before starting to make the canvas.
The linen is then cut to size allowing a sufficient margin around each edge for fixing to the stretcher.
The linen is fixed to the stretcher using a staple gun starting at the mid point on one of the longer sides. The next point to be fixed is at the mid point on the opposite side ensuring the canvas is tightly stretched.
A useful tip is to use a pair of carpenters pincers to grip the canvas and because of the curved end of the tool it is much easier to roll the tool to tighten the canvas before fixing.
After the mid points of one pair of opposite sides have been stapled, the same procedure is applied to the other pair of edges. The corners are tackled next using 'hospital corners' to obtain a neat finish. The pincers are particularly useful in helping to achieve this. Again the corners are treated in opposite pairs to give a uniform tension.
After the corners have been finished, additional staples are applied in between the corners and the mid points using an appropriate spacing depending on the length of the stretcher size, again stretching in opposite pairs.
The same technique can be used for non rectangular shaped canvases such as the oval shape seen above.
The next stage is to size the canvas. This is to protect the linen fibres and to seal any pinholes in the fabric. For this purpose the canvas is sealed with size made from rabbit skin glue. (See instructions below)
The size is brushed onto the canvas, worked in well, then left flat to dry. By holding the canvas against the light it is possible to check whether any 'pinholes' are present. If so a second thinner coat of size is applied. When dried, the sized canvas has a rough finish to the surface. A light rubbing with sandpaper leaves the surface smooth and ready for the gesso which provides a smooth surface on which to paint.
For the gesso, Sonia uses vinyl emulsion paint which can be tinted if required by adding a little acrylic paint. Sonia prefers to paint on a non white background, usually a neutral warm or cool grey. For portraits she prefers to use a pale green coloured background.
It is possible to re-use canvases (unless they have had heavy impasto applied). The technique is to lightly rub the surface with sandpaper or careful use of a palette knife, then reapply a new layer of gesso.
Sonia gave us a very different, but very informative and enjoyable evening and was warmy thanked by the members.
Scroll down for the Rabbit Skin Size instructions