Artist’s Assistant

The Artist’s Assistant, In the Study and Practice of Mechanical Sciences. Calculated for the Improvement of Genius, London – Birmingham [George Robinson] [s. d., 1780s ?].

Of PAINTING.

. . .

pp. 92–93

Fresco is a kind of painting performed on a fresh plaister, or on a wall laid with mortar, not yet dry, and with water colours.

The colours used, are white made of lime slaked long ago, and white marble dust; oker, both red and yellow, violet red, verditer, lapis lazuli, smalt, black earth, &c. all which are only ground and worked up with water; and most of them grow brighter and brighter, as the fresco dries.

This sort of painting is chiefly performed on walls and vaults, newly plaistered with lime and sand: but the plaister is only to be laid in proportion as the painting goes on; no more being to be done at once than the painter can dispatch in a day, while it is dry.

Before he begins to paint, a cartoon or design is usually made on paper, to be chalked and transferred to the wall, about half an hour after the plaister is applied.

Painting in oil is performed on walls, on wood, canvas, stones, and all sorts of metals.

To paint on a wall. – When well dry, you must give it two or three washes with boiling oil, till the plaister remains quite greasy and will imbibe no more. Over this are applied desiccative or drying colours, viz. white chalk, red oker, or other chalks beaten pretty stiff. This layer being well dried, you will sketch and design your subject; and at last paint it over; mixing a little varnish with your colours, to save the varnishing afterwards.
Others, to fortify their wall better against moisture, cover it with a plaister of lime, marble dust, or a cement made of beaten tiles soaked with linseed oil; and at last prepare a composition of Greek pitch, mastich, and thick varnish, boiled together, which they apply hot over the former plaister; when dry, the colours are applied as before.