The several artists who were desirous of knowing by what means the count came to make this discovery, made several attempts themselves; but in a great number of trials, only two are worth mentioning.
The first was to melt wax and oil of turpentine together, and use it for mixing the colours. But this method does not at all explain Pliny’s meaning; because wax is not burnt in this way of managing it: and besides, this method has two defects; the oil of turpentine dries too fast, and does not allow the painter sufficient time to blend and unite his colours.
The second method is very ingenious, and seems to come up to Pliny’s notion very well; it is as follows; the wax is melted with strong lixivium of salt of tartar, and with this the colours are ground. When the picture is finished, it is gradually put to the fire, which increases the heat by degrees; the wax melts, swells, and is bloated up upon the picture; then the picture is removed gradually from the fire, and the colours do not at all appear to have been disordered; the colours then become unalterable by the action of the fire, and even spirit of wine has been burnt upon them without doing them the least harm.
However, the following is the Count de Caylus’s method, which is much more simple; according to which the head of Minerva was painted, which was so much admired by all the connoisseurs.
First. The cloth or wood designed for the picture is waxed over, by only rubbing it simply with a piece of bees-wax.
Secondly. The colours are mixed up with common water; but as these colours will not adhere to the wax, the whole picture is to be first rubbed over with Spanish chalk, or whitening, and then the colours are used.
Thirdly. When the picture is dry, it is put near the fire, whereby the wax melts, and absorbs all the colours.
It must be allowed, that nothing can be more simple than this method; and it is thought, that this kind of painting is capable of withstanding the injuries of the weather, and last longer than painting in oil; which I will not answer for.
The effect produced by these colours upon wax is very singular; nor can one have any notion of it without seeing it. The colours have not that natural varnish or shining, that they acquire with oil; but you are capable of seeing the picture in any light, or in whatsoever situation you place it; in short there can be no false glare or light upon the picture for the spectators: the colours are secured, are firm, and will bear washing; and have a property, which I look upon as the most important of any, which is, that they have smoaked this picture in places subject to foul vapours, and to smoke in chimnies; and then by being exposed to the dew, it became as clean as if it had been but just painted.
These are all the contents of the letter, laid before the Royal Society by a member of that learned body, who accompanied it with a series of very acute and learned observations, which, with an extensive knowledge, shew an inclination to prove that the count’s method could not be the encaustic of the ancients, and that encausto pingendi could be nothing else but enameling.——