Dictionarium polygraphicum. Enamel.

Dictionarium Polygraphicum:
Or, The Whole Body of Arts Regularly Digested.
Vol I.
London: Printed for C. Hitch and C. Davis in Pater-noster Row, and S. Austen in St. Paul's Church Yard. MDCCXXXV.
ENAMEL, vulgarly call’d Amel is a kind of coloured glass, us'd in painting in Enamel.

The basis of Enamel is the finest crystal glass, made of the best kali from Alicant, and sand vitrified together.

To this glass are added tin and lead in equal quantities calcin’d by a reverberatory fire.

To this fundamental composition of Enamel, are added other metallick or mineral matters, to give it the various colours requir’d, as crocus martis for yellow, æs usium for green.

Enamel may be distinguish’d into three kinds.

The first intended for the counterfeiting and imitating precious stones.

The second is for painting in Enamel.

The third is us’d by the enamellers, jewellers, and goldsmiths on gold, silver and other metals.

The Enamel us’d in imitating precious stones, and also that for painting, is usually prepar’d by the workmen themselves, who are employ'd in those arts. The rest comes to us either from Venice or Holland; and particularly the white is that by which the makers of the Dutch ware give the lustre and polish to their works.

The composition is the same in the main in all the three kinds; the difference consists only in giving it the colour and transparency.

ENAMELs for painting.

The white Enamel us’d by painters in Enamel, is the same with the common Enamel us’d by enamellers; except that it is to be prepar’d by grinding and cleansing it with aqua fortis.

Then it is wash’d in fair water, pounded or ground over again in a mortar made of flint or agate.

The black is made of perigueux well calcin'd, and ground with oil of Aspic; having an equal quantity of the enamellers, or goldsmith's black added to it.

The ruddy-brown is made with feces of vitriol and salt petre, or with the rust of iron, well ground on an agate with oil of Aspic.

The yellow Enamel is the same with the goldsmith's Enamel, the composition of which you will see hereafter.

Vermilion red is made with vitriol calcin’d between two crucibles luted together; afterwards first wash’d in aqua fortis, and then in fair water, the fire must be moderate for about half an hour.

Lake red is compos'd of fine gold dissolv’d in aqua regia, with sal armoniac or common salt; when the dissolution has been compleated, it is to be put into a cucurbit with spring water and Mercury in a sand heat for twenty four hours. Then the powder which remains at the bottom of the cucurbit, after the water has been pour’d off, is to be ground up with double its weight of flower of sulphur, put into a crucible and set over a gentle fire. And after the sulphur which takes fire is exhal’d, the red powder which remains is to be ground up with rocaille.

Blue is made of the azure or lapis, us’d by oil-painters well purified and prepar'd with brandy, and set for five or six days in a bottle expos'd to the sun's rays.

An amber colour is made by white copperas calcin'd. These seven or eight colours or Enamels, serve for compounding all the rest; as blue and yellow make green, and so of other colours.

Jewellers, Goldsmiths and Enamellers Enamels.

These are brought to us chiefly from Venice or Holland in little thin cakes of different sizes; commonly about four inches diameter, having the mark of the maker struck on it with a puncheon.

The marks which are the most usual, are the sun, a syren, a monkey, or the name of Jesus, &c.

Those which come from Venice, are chiefly white, carnation, yellow, slate colour, sky-blue, green, and a deep blue call'd a false lapis.

These seven colours are the principals of all the others; which arise out of the mixture of these, and the white in particular, is as it were the ground of all the other six principal colours.

he white, as has been said, is made of crystal glass, and lead calcin’d by a reverberatory fire. This becomes a sky blue by adding copper and cyprus vitriol, a green by adding filings of copper, &c. a yellow by adding the rust of iron; a flesh colour by adding perigueux; and a slate colour by adding azures.

ENAMELLING is a method of painting with Enamel, or metal colours, ground, reduc’d to powder, and us'd with a pencil like other colours; then fus'd, bak'd again, and vitrified by force of fire.

This art is very ancient, and seems to have been first practised on earthen or potter's ware.

History makes mention of beautiful vases, enamelled with various figures made as early as in the age of Porsenna King of Tuscany.

It is true, these came far short in beauty to those afterward made at Faenza, and Castle Durante in the Dutchy of Urbino, in the time of Raphael and Michael Angelo.

Some of these vases are still to be seen in the cabinets of the curious; the design or drawing of the figures of all which are much superior to the colouring; they of those times being un acquainted with the art of making any more than two colours, viz. black and white, either for earthen or metal works; excepting a faint kind of carnation in the faces and other fleshy parts.

The art was retriev'd in France in the time of Francis I, and particularly at Limoges; where many valuable pieces were wrought, after the Inanner of the ancients, i. e. perform'd well as to the drawing, and clair-obscure, chiefly in two colours.

There are two ways of painting in Enamel; the one with clear and transparent, and the other with thick and opake, colours.

To make the first fit for use, they are only to be ground up with water, and for the second with oil of Aspic.

The first are laid on the metal flat, and bordered or edg'd with a run of the metal, to keep the colours asunder, though there are some pieces, the colours of which have been laid on contiguous, and without any partition; which is very difficult to do, by reason the transparent colours in melting are apt to run the one into the other; especially in the little works.

The invention of opake colours is of a much later date, and by much preferable to that of transparent ones.

But all metals will not equally admit both kinds; as for in stance, copper will not bear all the transparent colours, which bears all the opake ones; but in laying the transparent ones, they are forc’d first to cover it with a lay or couch of black Enamel, and upon that lay leaf of silver, and apply upon this other suitable colours, i. e. the colours and Enamels proper for silver, which itself does not allow of all kinds.

Those which suit best with it are purple, green, azure, and aqua marine. But gold receives all kinds and colours perfectly well, both opake and transparent.

But then the gold us’d must be the very finest. For if the transparent colours are laid on a base gold, they will grow dim and livid; there being a kind of smoke that settles on it not unlike black-lead.

Of transparent Enamels the hardest are the best; although there is a difference even among these, some retaining their colour in the fire, and others losing it.

As for the reds, they are only red by accident; they being only yellow when made and apply'd on the gold, and becoming red in the furnace.

The best transparent reds, are those made of calcin’d copper, iron rust, orpiment, and calcin'd gold, melted with the due proportion of glass.

But all our fine modern pieces of Enamel are owing to the method of painting with opake or thick Enamel; particularly those curious ones on gold, representing portraits to as great perfection, as the best painting in oil, and even some history pieces; with this great advantage, that their lustre never decays.

The French claim the invention of this art; nothing of the kind having been attempted before the year 1630, when Jean Toutin, a goldsmith of Chasteaudun, and a great master in the common way of painting in transparent Enamel, first apply'd himself to the finding out a way to use thick colours of different teints, which should melt with fire; but yet retain their lustre, purity, &c.

Toutin succeeding in his attempt, and having got the secret communicated it to his fellow artists, who also in their turns contributed to the bringing it to a higher perfection.

The first that distinguish’d himself was one Dubie, who wrought in the galleries of the Louvre; to him succeeded Mortiere, a native of Orleans, who apply'd himself chiefly to the painting of rings and watch cases.

But Robert Vauquer of Blois, scholar to Mortiere, exceeded all that had been before him both in design and colours.

And Pierre Chartier of Blois, betook himself to the painting of flowers, wherein he succeeded to admiration.

By this time the English were fallen into the way, and were the first who apply'd it with success to the painting of pourtraits, which was now grown mightily in vogue in the place of those in miniature; M. Felibien observes, that the first and most finish'd pourtraits, and those in the finest colours were brought into France by Petitot and Bordier from England; this put Louis Hance and Louis Guernier, two good painters in miniature, to attempt the like, in which the latter succeeded beyond every body.

He was also the inventor of several new teints for carnations, and had he liv'd much longer had probably merited the glory of carrying the art to its last perfection.

This kind of painting to be in perfection must be done on plates of gold; for silver turns the whites yellow and copper, besides that it emits a fume, which tarnishes the colours, is apt to scale and crackle.

These plates must be made a little hollow on one side, and rais'd on the other, either in a circular or oval form, to prevent the gold's fretting by the fire, and making the colours crack and fly; nor must they be made too thick.

It is enough if they can bear the colours; though it is usual to strengthen them all around with a circle something thicker. The plate having been hammer'd very evenly throughout, a white Enamel is laid on both sides, although but one of them is to be painted. The design of this is to prevent any swelling and warping by the fire, for otherwise in large pieces, and especially if the colours be laid on any thing unequally, they are apt to rise up in puffs and blisters.

Now this first lay which is white, remaining smooth and uniform, serves as a ground for all the other colours.

The gold plate being thus enamelled with white; the draught or design to be painted must be chalk'd hereon, and afterwards the whole accurately drawn out in a ruddy brown.

The draught or out-line being thus finish'd, the piece is set to the fire, and then painted with the colours.

The white ground painted on serves all the colours for white, it being the usual method to spare the ground from first to last, in the places where the lights are to be, after the same manner as in miniature; though they have another white to lay over the other colours, when there is occasion to raise them.

As painters in oil retouch their paintings several times, and let them dry, so in this sort of painting they touch the piece as often as they please, setting it each time to a reverberatory fire, and taking it away again as soon as they perceive the Enamel has got its full polish.

The reverberatory fire is made in a little furnace, wherein there is fire both at top and all around; only a void place in the middle, where the piece is to be put for the Enamels to melt. See the plate.

The colours are laid on with the tip or point of the pencil, as in miniature; with this only difference, that they use oil of Aspic to dilute them instead of gum water. See MINATURE.

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