Merrifield, Mary P.: The art of fresco painting, as practised by the old Italian and Spanish masters, with a preliminary inquiry into the nature of the colours used in fresco painting: with observations and notes (London: Charles Gilpin, 1846)

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FRESCO PAINTING.

should be also another jar full of water, with a brush for moistening,
and rubbing from time to time the part which has not been painted,
that it may not dry. For after it has been left some time, a film or
pellicle forms over the surface of the lime or stucco which fills up
the pores, so that it does not absorb the colour which crumbles off
like ashes; and the tarea should be wetted, although the stucco does
not dry, for if it should dry before it is finished, it would be useless
and must be cut out, and the stucco must be again spread and the
subject drawn on it again ; but the water in this second jar will not
serve for sprinkling the part that is painted, because bv rubbing the
plaster with it, it takes up a little of the white, and if this were used
for sprinkling, the picture would be spoiled.
This is the process, supposing it fine weather; for if it freezes,
(which is the worst weather there can be for this kind of painting),
the two vases of water should be put over the fire, that the water
may be warm, and with that the surface may be sprinkled or bathed,
in the before-mentioned manner ; even the water that the mason
uses should be warm. All this is necessary during a hard frost, for
if the intonaco should freeze, it is the worst thing that can happen,
as no absorption takes place, and the colours do not incorporate with
the intonaco, but crumble off like ashes, as I know by experience;
and if all these means should not suffice, the work must be left till
the weather is milder.
Of the colours used.—Before we proceed further, the colours
which are used in fresco painting may be briefly described. They
are all mineral,a and some are calcined by means of fire. The mine-
ral colours are, Light Ochre, Dark Ochre, Tierra Roxa, Albin, Pa-
vonazo, Sombra de Venecia, Sombre del Viego, Tierra Verde, and
Tierra Negra. Those made by means of fire, are Esmalte, Negro de
Carbon, Burnt Ochre, Hornaza, Burnt Roman Vitriol, and Vermilion.
The best kind of Vermilion is the mineral or native Vermilion, but in
uncovered places, neither the mineral nor the artificial is good for

a Palomino means to say, that the colours consist of natural pigments only,
but of these some merely require to be washed and ground, while others require
to be calcined. All the nine pigments of the first class mentioned by the author
contain more or less of iron, the other ingredients being silica, alumina, magnesia
and manganese. These are the pigments, which, in all ages, from the Egyptians
and Greeks, to the present time, have been found most permanent.