Complete Artist’s Manual: The Definitive Guide to Materials and Techniques for Painting and Drawing. Simon Jennings
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Acid content
Papers that contain an acid presence, such as newsprint and brown wrapping paper, are prone, in time, to yellowing and deterioration. Paper acidity is measured by the pH scale. An acid-free paper does not contain any chemicals which might cause degradation of the sheet, and will normally have a pH of around 7 (neutral). All good-quality watercolour papers are acid-free, to prevent yellowing and embrittlement with age. Some are also buffered with calcium carbonate, to protect against acids in the atmosphere.
Increasing sizing
If paper is too absorbent, paint sinks into it and colours appear dull. To remedy this, dissolve a teaspoon of gelatin granules in 500ml (18fl oz) of water and apply to the surface before painting.
Reducing sizing
If a heavily sized paper does not take paint well, then pass a damp sponge over the surface several times. Leave it for 30 minutes, then dampen again before painting. Some handmade papers may need to be soaked for up to two hours in warm water.
Trying for size
The amount and quality of sizing varies according to the brand of paper. A quick test is to lick a corner of the paper with the end of your tongue: if it feels dry and it sticks to your tongue, you will know that it is absorbent paper.
Spiral pads
Watercolour paper can also be purchased in the form of spiral-bound pads, which are convenient for outdoor sketching. They generally contain 300gsm (140lb) Not paper.
SEE ALSO
| STRETCHING PAPER | Wet paint causes the fibres in watercolour paper to swell, and this can lead to buckling, or ‘cockling’, of the surface. To prevent this happening, you should stretch paper before starting to work on it. |
Achieving a smooth painting surface
The paper is wetted and then securely taped to a board. On drying, it will contract slightly and become taut, giving a smooth surface that is less prone to cockling. With heavier papers (300gsm and over) there is less need for stretching, unless heavy, saturated washes are to be applied. Lighter papers always need stretching.
Method
Cut four lengths of gummed brown-paper tape 50mm (2in) longer than the paper. Do this first, to avoid panic at the crucial moment, when wet hands, crumpled tape and a rapidly curling sheet of paper could cause chaos.
Immerse the paper in cold water for a few minutes (1), making sure it has absorbed water on both sides; heavier papers may take up to 20 minutes. Use a container large enough to take the sheet without being cramped. For large sheets, use a clean sink or bath.
Immerse only one sheet at a time in fresh water, as each sheet will leave a residue of size in the water.
Hold the paper up by one corner and shake it gently to drain the surplus water. Place the paper onto the board (2) and smooth it outwards from the centre, using your hands, to make sure that it is perfectly flat.
Take a dry sponge around the edges of the paper where the gummed tape is to be placed, to remove any excess water (3). You should moisten each length of gum strip with a damp sponge immediately before use. Beginning with the long sides, stick the strips around the outer edges of the paper, half their width on the board, half on the paper (4).
Leave the paper to dry flat, allowing it to dry naturally, away from direct heat. Do not attempt to use stretched paper until it is dry. Leave the gummed strips in place until the painting is completed and dry.
Commercial paper stretchers
For those artists who find stretching paper a time-consuming chore, the only previous alternative to this has been to use expensive heavyweight papers or boards. However, there are now various effective devices available, which are designed by watercolour painters and which will stretch lightweight papers drum-tight in minutes. Among the ingenious designs, one uses a two-piece wooden frame to hold the paper firmly in place as it dries; another employs a system of plastic gripper rods which are pushed into grooves in the edges of the board, to hold the paper.
Choosing the best equipment
Use only gummed brown-paper tape for stretching paper – masking tape and self-adhesive tape will not adhere to damp paper. A clean wooden drawing board is the ideal surface for stretching paper; traces of paint or ink might stain the paper. Plastic-coated boards are not suitable, because gummed tape will not stick to them.
Immersion times
(1) Immersing the paper
(2) Smoothing the paper
(3) Removing excess water
(4) Sticking the gummed strip
These depend on the weight and degree of surface sizing of the paper. Thin paper soaked for too long will expand greatly, and may tear as it contracts; too brief an immersion means the paper will not expand enough, and will buckle when wet paint is applied. The correct soaking time for each paper will come through trial and error, but in general lightweight papers and those not strongly sized should be soaked for 3–5 minutes; heavily sized papers may need 15–20 minutes. (If a fine layer of bubbles appears when the paper is immersed, this indicates a strongly sized paper.)
| SUPPORTS FOR PASTELS | Some pastel artists like to work on primed hardboard, muslin-covered board or canvas, but most prefer to paint on one of the many tinted papers made specially for pastel work. |
Effects
The subtle texture of pastel