Читать книгу Painting Expressive Watercolours - Mike Chaplin - Страница 10

It is difficult to find a recipe for grinding paint and you will learn mainly by experience, but my method is to use four parts of gum arabic to one part of glycerine or glycerine mixed with honey, with a few drops of ox gall and vinegar. You can either make a stock solution of all those ingredients and store it in a bottle, or make a pile of pigment and add the ingredients separately to it. The binder will keep indefinitely but it will thicken if there is air in the bottle, so as you progressively empty the bottle it is a good idea to add some marbles to replace the binder or to buy a ‘concertina’ storage container from a photographic shop that can be squeezed smaller.

To grind the paint, add just enough binder to the pigment to make a workable mix and incorporate it with a palette knife until you have a wet, creamy mixture. This will be very coarse, so the next step is to grind it with a muller on a slab or with a pestle in a mortar, adding enough water to make it workable. Although most tap water is pure enough to use, it is best to buy distilled water to make sure the colour is not affected.

In the case of colours such as Burnt Sienna and Burnt Umber which are natural earth pigments, albeit already sifted and pounded, you will be able to hear their grittiness and you will learn to judge by ear how coarsely or finely you have ground them. Grinding the paint generates quite a lot of heat and dries the mixture, so you will need to add more water as you go. When the paint is the consistency you want, you can use it immediately or store it for later.

Grinding equipment

A heavy glass muller, available from the supplier of the pigment, is used on a ground-glass slab. A cheaper alternative is a glass, earthenware or porcelain pestle and mortar, available from hardware shops. Do not use a wooden pestle as you will not obtain sufficient grinding power.

Storing

Pigments can be stored in pots obtained from a pharmacist, in emptied pans from a paintbox or in shells – the traditional way to transport paint before tubes and pans were invented. The Cobalt Blue shown here is much more heavily granulated than you would find in a commercially bought form.