Secrets of Glass Manufactory - Compositions to Imitate Precious Stones, called French Paste

Secrets Concerning Colors and Painting
§ I.  Paint In Varnish On Wood
§ 2. Paint On Paper
§ 3. Compositions For Limners
§ 4. Make Transparent Color
§ 5. Compositions to Dye Leather
§ 6. Color or Varnish Copperplate Prints
§ 7. For Painting on Glass
§ 8. Color Preparation for Oil, Water, and Crayon
       Marble and Jasper Paper
       Methods to Clean Paintings
       Making Good Crayons
       Directions for Coloring Prints
       Directions for Painting in Oil
§ 9.  Preparation of Lapis Lazuli to Make Ultramarine

II.  A way of making diamonds.
    Grind on marble, equal quantities in weight of calcined silver, and French loadstone.  Stratify in a crucible, your crystal stones, ready cut in imitation of diamonds, with this powder.  Cover it with another crucible, and lute it well.  Then set it in a glass-maker's furnace, for one month.

III.  To soften crystal, or any other coloured stone, so that you may cut it like cheese; and restore it afterwards to its primary hardness.
    1.  Take, in the month of August, goose's and goat's blood.  Let each of them dry till very hard.  When you want to soften your stones, take an equal quantity of each blood, pulverize it and put in a pot, then pour over a strong lye made of pearl ashes.  Leave it so for a while, stirring often; then add about a pint of strong vinegar.  In this preparation, if you set your stones, and warm it a little over the fire, they will become so soft, that you may take and cut, or form them afterwards as you will.
    2.  To restore them again to their former hardness, put them in cold water, and let them there lay for about one hour and a quarter, it will be quite sufficient.
    3.  But to give them their lustre again, you must take antimony in powder, spread it on a very smooth leaden table, then polish your stones on this.  It will restore them to their brightness as before.

IV.  Another equally useful to soften crystal and steel.
    Make a strong lye of quick lime and pearl ashes.  Run it nine or ten times more over new live and new pearl ashes, each time.  Then put to soak, in this preparation, and piece of crystal or steel, for the space of twenty-four hours, and you will see what a surprising degree of softness they will have acquired by it.

V.  A paste, which will produce as beautiful emeralds as natural ones.
    Calcine, six times, rock crystal, and plunge it as many times, in pure cold water.  Grind it into powder, on a rock crystal stone, with a mullar of the same.  When you have rendered the powder very fine and impalpable, to one pound of it, add another of salt of tartar, drawn from red tartar, mixed well.  Join to this, sixty grains of red copper, and fifteen of silver, both in shell, but grinded separately.  Now mix the last powders with the former, on a marble stone, and put all together in a clean and double nealed crucible.  Lute it well with its lid, and when the lute is perfectly dry, put the crucible for six days on a clear but gentile fire; then increase the fire till the crucible becomes red hot. place it immediately in the ardent and glass melting furnace, and keep it there in the same degree of heat for a month, without interruption.  Then let the crucible cool gradually in the furnace, which is done by letting the fire go out of itself, having previously stopped all the holes and openings of the furnace.  When you break it, you will fine a beautiful green, which is fit to cut by the lapidary.
    Note.  Be careful of this composition, for it has all the merit and advantage of the true emerald.  It vies with it in weight, colour, and hardness.  In short, the greatest connoisseurs cannot distinguish these emeralds from the finest real ones.

VI.  A composition, the fundamental basis of all enamels.
    1.  Grind on marble, and sift through a very fine sieve, equal quantities of lead and pewter-calx.  Put it in a varnished pipkin filled over with water.  Boil it some while; then pour it by inclination, into another vessel.  Put new water, to boil again over the calx. and decant it as before, on the first water: which process you repeat till you have entirely dissolved all the calx.  If some part of the metal remain at the bottom, too gross to be entirely carried by the waters, it must be put in a   melting-glass furnace to calcine, having care to take out, in proportion as it turns into calx, the upper part of the matter.  When it is all calcined, continue dissolving it, by means of boiling water, as you did at first.  When you have got all your waters of dissolution, vaporise them over a slow fire; and particularly towards the end of the evaporation, have a singular care that the fire be not too fierce, which then remains at the bottom, very fine and subtilized.
    2.  To twenty-five pounds of this calx add an equal weight of frit, made of tarce, or white sand, well pounded and sifted through a very fine sieve, and four ounces of white salt of tartar, pounded and sifted in the same manner.  Put these ingredients in a melting-glass furnace; melt and purge them there for ten hours.  Then having taken the pot off from the fire, take out the matter, which, after having well pulverised, keep it in a close dry place, where dust cannot come at it.-- Such is the first and principle matter to be used in the composition of enamels, of whatever sort of colour you want to make them.

VII.  To make an enamel as white as milk.
    1.  To six pound weight of the matter just described, put forty-eight grains of magnesia, prepared as follows.
    2.  Put in an iron spoon, to the reverberating fire, the bits of magnesia, rough as it comes from the mine.  When it is whitened, pour good vinegar over it, then break it small, and wash it several times with warm water.  Dry, pulverise, and sift it, then preserve it in a covered pot for use.
    3.  This Magnesia, and primary enamel matter, you put in the above prescribed proportion, in a crucible, on a glass melting fire, then throw the whole contents into clear water; dry it, melt it again, and before, and throw it in the water again, and so on.  This operation repeat three times.  Being thus well purified, if you find it not quite white enough, add a little more magnesia, and begin the same process as before.  Then take it off the fire, and make it into small round cakes.  Such is the method of preparing the enamel to paint with on gold and other metals.

VIII.  To make an enamel turquoise colour.
    Put six pounds of the said enamel primary matter in a varnished crown-glass pot.  Melt and purge it three times as usual as prescribed in the preceding article.  On the third time project a four separate times, three ounces of scories of copper, prepared as directed in Art. IX. mixed with ninety six grains of zaffar prepared the same way exactly, and in the same manner as the magnesia, and forty-eight of that very magnesia in subtile powder.  Stir well the matter on the fire, at the time of each projection, with a long-handled iron hook; and when the colour seems to be to your liking, take it out of the fire, and make into small round cakes as usual.  This will make a most beautiful turquoise enamel.

IX.  How to prepare the scories of copper for the above purpose.
    This preparation is very simple.  Wash first, the scories well, and set them to calcine three days at the entrance of a reverberating furnace.  Then grind this and sift it.  Calcine again as before, grind and sift the same, repeating this operation three different times.  When finished, it is called a calx of copper.  Of this, mix three ounces with forty-eight grains of prepared magnesia, and ninety-six of saffar also prepared, for a projection on enamel's primary matter, to make a fine sort of turquoise colour.

X.  To make blue enamel.
    Put in a varnished crown glass pot, in a melting glass furnace, four pound of common primary enamel matter; two ounces of zaffar, and forty eight grains of prepared scories of copper, all previously well pulverised and mixed.  When this composition is in good fusion, throw it in water, then dry it and put it again in the same pot.  Leave it there till the matter is well incorporated. and proceed as directed for the others.

XI.  To make green enamel.
    1.  Melt and purge, by the glass melting fire, and in a varnished crown glass pot, four pounds of the primary enamel matter.  Leave it there twelve hours, after which throw it in water, dry it, and put it again in the same fire, for the same time, to cleanse it well.
    2.  Grind into a very subtile powder, some of the aforesaid scories of copper, and some scories of iron.  Mix these powders together, viz. two ounces of the former, and forty eight grains only of the latter; which being divided into three different parcels, project, at three distinct times, on the enamel matter in fusion, stirring well with an iron hook at the time of each projection, that the colour may better incorporate; and in twelve hours afterwards you will find a very fine green enamel.

XII.  To make a black shining enamel.
    Take of our primary enamel matter in powder, four pounds; red tartar, four ounces; and of your prepared magnesia, in subtile powder, two.  Put all this into a varnished pipkin, so large that all these powders together shall not come higher than the third part of the vessel, this matter, when melted, swells very much.  When in perfect fusion, throw it into water; take it out to dry, then put it again in the pot, and purify it as before.  Do so till you find it sufficiently purified; then take the pot off the fire and the matter out of the pot.

XIII.  To make an enamel, purple colour.
    Reduce into subtile powder, and mix well together, six pounds of our primary and general enamel matter; three ounces of prepared magnesia, and six so scories of copper, prepared as before mentioned.  Melt and purify all this in a varnished pipkin, by placing it in a melting glass furnace.  When in good fusion, throw this matter in water; dry it, and put it again in the same pot to purify it anew by the same process.  If you find your colour to your liking, take the pot off from the fire, and keep you enamel for use.

XIV.  Another.
    Take six ounces of our general matter, two of prepared magnesia, and forty-eight grams of the aforesaid preparation of scories of copper.  Pulverise, and proceed as above.  this composition will give a very fine purple enamel, fit for all sorts of works which goldsmiths will employ it in.

XV.  A yellow enamel.
    Take, and reduce into a very fine powder, six pounds of the general matter; three ounces of tartar, and seventy-two grains of prepared magnesia.  Put all into a pot large enough not to lose anything of the matter when it comes to swell at the time of its fusion.

XVI.  To make a chrystaline matter which serves as a basis to red-colour enamels.
    1.  Take twenty-four pounds of salt, drawn from trituration, lotion, filtration, and evaporation; and sixteen pounds of white tartar, that is to say, of white and transparent river pebbles, calcined and reduced into a subtile powder, mix and wet them so as to make a hard paste of them, of which you will form small thin cakes.  Put these cakes in pipkins, and place them in a lime, or potter's kiln, where they are to calcine for ten hours.
    2.  Then these cakes are well calcined, reduce them into a subtile powder, add four pounds of lead and pewter calx (prepared and subtilized as before directed, Art. VI.) and as much white tartar also calcined and purified by lotion, etc.  These three last ingredients being reduced into a subtile powder, put them in a varnished pipkin, and place them in a melting glass furnace, there to be melted and purified, by throwing the composition, when in fusion, into water, then drying, etc. three times, after which the whole is completed.

XVII.  How to make a fine preparation of fusible magnesia, to be employed in the making of red enamels.
    1.  Take whatever quantity of magnesia you please.  Add to it an equal quantity of nitre prepared by lotion, filtration, and evaporation.  Set this matter in a pipkin to calcine for twenty-four hours, by reverberating fire.  Then take it out, and wash it with warm water, to cleanse it from all the nitre, and dry it.  When this magnesia be dry, it will be of a very fine red.
    2.  Now add to it its equal weight of armoniac salt.  Grind all well on a marble stone, wetting it with distilled vinegar, so that it comes into a sort of clear paste, or colour for painting.
    3.  Then dry this matter; and, having pulverised it, put it a subliming in a strong glass matrass, with a long neck and a large belly.  Give it the sublimating fire for twelve hours; break the matrass; weigh first the sublimed part, and mix it with what remained at the bottom; add ad much new ammoniac salt as you had weight of sublimation.  Grind these well together, wetting them with vinegar, then dry and sublime again as before.  Renew this operation so many times as will be requisite, that the magnesia remain at last in a state of fusibility at the bottom of the matrass.
    4.  This liquid is fit for staining crystal of a very fine ruby hue; and, when employed with enamels, will render them of a most beautiful red.

XVIII.  To make red enamel. of a beautiful ruby hue.
    Put twenty ounces of the above fusible magnesia, to one pound of the crystaline matter (Art. LI.) in good fusion.  Purify the whole well, and try the colour.
    Note.  According to the proportion of fusible magnesia you put in this composition, you raise of lower the hue of your enamel.  And, if carried to the degree of rubies, it will prove bright and beautiful.

XIX.  To make an enamel, true Balais-ruby colour.
    Take ten pounds of our crystaline matter.  Purge it in the melting glass furnace, by fusing it, then throwing it in water, drying, pulverising and melting again, etc. three times.  Put it again for the fourth time in fusion; and, when in that state, give it the purple colour by means of a proper quantity of fusible magnesia, as mentioned in the preceding article.  After this project on it, at eight different distances of time, as much calcined alum, in subtile powder, as you will find requisite to give it that degree of red hue you desire; which to imitate the Balais ruby colour, must be fuller and deeper than that of the clear rubies.

XX.  To make a bright enamel, escarboucle colour.
    1.  Take very fine gold, one part.  Purify it again, and open it in the following manner.  Dissolve it in good regal water; distil it first from the gold, and recohobate it six different times.  After this, take your gold powder from the vessel, put it in a crucible, covered and luted as usual, and place it in a furnace to the reverberating fire, where it shall be left to calcine till it becomes a very high and deep red, which cannot happen till after several days calcination.
    2.  Then, by projecting this part of well opened gold on twenty of the before mentioned crystaline matter, previously purged according to direction, and put in a state of good fusion, an enamel will be obtained, of the most beautiful, transparent, escarboucle colour.

XXI.  To make transparent frames.
    Boil for a quarter of an hour only, nut oil, six ounces; white wax, four; rosin, as much; and Venice turpentine, two.  When lukewarm, lay it on with a soft brush.

XXII. A white paint to preserve the putty round the panes of glass.
    1.  Grind white lead with water.  Dry it, and grind it again with oil, then lay a coat of it over your putty.  But if you want it to be still more durable, put two coats of it, after having added a part of foetid oil, made in the following manner.
    2.  Have a leaden plate with turned up edges to make a border.  Fill it with nut or lintseed oil.  Cover it with a piece of glass, and espose it in the sun.  It will soon  be foetid.

XXIV.  To clear glass.
    Rub the glass crystal with a piece of lead; that will make it clear and bright.

XXV.  How to distinguish a true form of a false stone.
    Warm an iron plate; rub some oil over it; spread glass dust on the middle, and cover that glass with kindled coals.  Hold the stone you want to try over these coals, without letting it touch them.  If the stone does not lose its lustre, and look dull, it is a true stone.

	Web old-crafts.com