Break the egg into a jar. Using the eggshell as a measure, add the same volume of refined linseed oil and twice the volume of cold water. Screw the lid on the jar and shake vigorously until an emulsion is formed. Grind a little emulsion with titanium white pigment until it forms a stiff white paste; add the rest of the emulsion to bring the mixture to the consistency of double cream. Thin the mixture to a milky consistency with lukewarm glue size mixed 1 part to 12 parts cold water. Brush very thinly onto a sized support.
Traditional gesso
Brilliant white gesso (see ingredients here), is very smooth and porous, and is the ideal base for painting luminous colours and detail. Gesso is best applied to a rigid support prepared with glue size – it is not flexible enough for use on canvas. It is most suited to water-based paints, such as tempera, acrylics and Chroma colours.
Heat the size, mixed 1 part to 8 parts cold water, gently in a double boiler. Slowly add some warm size to the whiting and stir until it forms a thick paste. Blend without creating excess bubbles. Gradually add the rest of the size until a smooth, creamy mixture is obtained. (Keep the pot of gesso warm and covered, otherwise it will harden, the water will evaporate and the glue will become too strong.) To increase the brilliance, add powdered white pigment. Leave for a few minutes before using.
Applying gesso
Apply gesso carefully in thin layers and work quickly: if you go back over an area, streaks will develop. Dampen the brush with some water to prevent air bubbles forming on the surface. Apply the first coat of hot gesso in short, even strokes (1), keeping the working edge moving – when the gesso begins to cool, move on to an adjacent area. Apply up to six coats for a dense, white finish; add each coat at right angles to the last (2), using short back-and-forth strokes. Each coat should be completely dry before the next one is applied. Level off in one direction (3). Lightly sand between coats with fine sandpaper (4), dusting off the surface before applying the next coat.
Egg-oil ingredients
• titanium white pigment
• one egg
• linseed oil
• glue size
• water
(1) Applying the first coat
(2) Adding coats at right angles
(3) Levelling off
(4) Sanding between coats
Gesso ingredients
• 1 part Gilder’s whiting
• 1 part glue size
Sealing gesso
On an absorbent gesso surface, oil paint takes on a matt, airy quality which is pleasing but makes the paint quite difficult to handle. In addition, gesso soaks up much of the oil from subsequent paint layers, leaving them brittle and prone to cracking. To overcome this, the dry gesso surface should be partially sealed with a weak solution of glue size (about half the strength used to make the gesso).
SEE ALSO
| TONED GROUNDS | Some artists like to paint on a toned or coloured ground, as a white ground can be inhibiting; by covering the canvas or paper with a wash of neutral colour, you immediately create a more sympathetic surface on which to work. |
‘Reading’ tones and colours
A white ground can give a false ‘reading’ of tones and colours, especially in the early stages of a painting, when there is nothing to relate them to. Most colours appear darker on a white surface than when they are surrounded by other colours, and this creates a tendency to paint in too light a key. If you work on a neutral, mid-toned ground you will find it much easier to assess colours and tones correctly, and you can paint towards light or dark with equal ease.
If the colour of the ground is allowed to show through the overpainting in places, it acts as a harmonizing element, tying together the colours that are laid over it.
Choosing a ground colour
The colour chosen for a toned ground will depend on the subject, but it is normally a neutral tone somewhere between the lightest and the darkest colours in the painting. The colour should be subtle and unobtrusive, so that it does not overwhelm the colours in the overpainting. Diluted earth colours, such as Venetian red, raw sienna or burnt umber, work very well, as do soft greys and greens.
Transparent and opaque grounds
A toned ground can be either opaque or transparent. With a transparent ground (also known as imprimatura), the paint is heavily diluted and applied as a thin wash. A transparent ground allows light to reflect up through the succeeding colours, thereby retaining their luminosity, and it is used where transparent or semi-transparent colour is to be applied. Opaque toned grounds are used with opaque painting methods, where the light-reflecting qualities of a white ground are not so important.
Applying transparent grounds
Dilute the colour until it is thin, and then apply it with a large decorator’s brush or a lint-free rag. Loose, vigorous strokes give a more lively effect than a flat stain of colour. After a few minutes, you should rub the wash with a clean rag, leaving a transparent stain.
Making opaque grounds
Mix a little tube colour into the white priming or gesso before applying it (see here). Alternatively, you can mix the colour with white paint, dilute it a little, and then brush a thin layer over the priming. Never mix oil paint with an acrylic primer, or vice versa.
Drying times
A toned ground must be dry before you can paint over it. An oil ground takes a day or two to touch-dry; an acrylic ground is dry in minutes. So long as it is applied thinly, you can use acrylic paint for the toned ground and work over it with oils.
Ground colours
Diluted earth colours, such as Venetian red, raw sienna or burnt umber, are subtle and unobtrusive.
Jacqueline Rizvi
Two Apples
Watercolour and body colour on toned paper