Talking – as I was, with someone the other day – about the various methods I employed to simulate tortoise shell (and indeed, ‘tortoise shell’) on an earlier girandole and chest of drawers I made; I herewith append (as promised) William Salmon’s instructions that I have zealously adhered to – more or less – for several decades.
That which we endeavor to imitate is Tortoiſe Shell laid, upon Silver Foil, which gives it life and beauty: now to imitate this well, let your Wood be cloſe girain’d, ſmooth, and well wrought, as Box, Pear-tree, Wallnut-tree, &c.
Then take a fit varniſhing Pencil [camel hair brush] and with your thickest Seed-lac Varniſh ſtrike over the breadth of a Silver Leaf, which taking up with Cotton, lay on Upon your Work whilſt it is moiſt, dabbing it cloſe to the Work, as you are taught in Gilding.
This done, Varniſh another Place, and in like manner lay on another Leaf of Silver as before, and, ſo continue, till the whole Work is covered over with Leaf Silver: and then let it dry throughly, and with a fine [hog’s] Hair Bruſh ſweep off all the looſe Silver.
Take Lamp-black, or rather Cologne Earth, (which comes neareſt to the Color of the Shell) and grind it with Parchment Size, or Gum-water, till it becomes very fine and impalpable: and being finely ground, mix it with more Parchment Size or Gum-water, agreeing with that you firſt ground it withal.
With this mixture ſpot the darkeſt part of your Shell, after a careleſs cloudy manner, imitating Nature as much as may be, letting a piece of the true Shell lie by you to look upon, thereby to acuate your Fancy and Genius.
Take Gum-water and therewith grind fine Sanguis Draconis [dragon’s blood] very ſoft; but ſome grind the Sanguis Draconis dry, till it is very fine, and then mix it with fine Seed-lac Varniſh, which is moſt proper and agreeable for this Work, and not ſo apt to Poliſh off as Size or Gum-water.
Now whereas, there are ſeveral Reds lighter and darker to be found on the edges of the blacker Part, and ſometimes lie in Streaks, and Clouds, on the tranſparent part of the Shell, we are now to imitate that with one of the two former mixtures of Dragons Blood.
Dip a ſmall Pencil into one of thoſe mixtures, and daſh the said Reds, fluſhing them in and about the dark Places, both thicker and thinner, fainter and lighter, and, with leſs Color towards the lighter part of the Shell; then ſweeten it ſo, that by degrees, it may ſo looſe its ſtrengih of Redneſs, as to be quite loſt in the Silver, or more tranſparent parts of the Work.
This done, give it 6 or 7 waſhes of fine Seed-lac Varniſh, and letting it dry 1 or 2 days, ruſh it gently and very ſmooth, to make it fit for the next Operation.
[Take] Fine Sanguis Draconis, Cambogia [gamboge], grind them dry to ſubtil Pouder; mix it with as much fine Seed-lac Varniſh, as may Varnilſh the piece 6 or 7 times more: and let it dry 12 hours or more.
Then give it another or third Varniſhing with the laſt mixture, doing it ſo often over, till the Silver ſeems to be changed into a Gold-like Color.
Laſtly, take heed that your Varniſh be not too thick and high colored with the Sanguis and Cambogia, but rather heighten it by degrees, leſt your Silver be too high colored, before it has received a ſufficient Body of Varniſh. Let it dry 6 or 7 days, then Poliſh and clear it up, as before directed.
Another Tortoife Shell Japan:
Firſt prime your piece very well, then Lacker and Size it in Oil. Then lay on your Leaf Silver, and let it dry very well: and have ready finely ground in Oil, theſe Colors, Red Lake, Cinnabar, brown Pink, Cologne’s Earth, and burnt Umber, placing them diſtinctly on your Pallet.
Strike over your work with Turpentine Varniſh and whilſt it is wet, mix lake and brown Pink, thin with Varniſh, and with it lay all your fainteſt Clouds or Spots, which ſoften ſweetly whilſt the Varniſh is moiſt.
Let it ſtand four hours or more, and if the Colors are dry, with a large ſoft Pencil, paſs it lightly over again: and again moiſtning it, put in more Clouds, which more and more darken with Umber, and Cologne Earth, before it is dry; always obſerving the Life, and ſweetning your Work, which is by blending, and inſenſibly mixing the Colors after they are laid, so as you cannot perceive where each of them begin or end.
If the Clouds are not dark enough, reiterate the Clouding and Varniſhing once more, as you ſee need requires: when well dryed, Glaze it 2 or 3 times with brown Pink, with a little Tincture of Verdigriſe in it: or you may Varniſh it with fine Seed-lac Varniſh, and then finiſh it as the former.
And another Tortoiſe Shell Japan:
Firſt lay a white Ground as before taught: then with proper Colors, as Vermilion, auripigment [orpiment], &c. duly mixt with common Turpentine Varniſh ſtreak and cloud, or ſhaddow the white Ground with any irregular fancy you pleaſe, as nearly imitating Tortoiſe Shell as you can.
Let it throughly dry, and then ſtrike it here and there with the reddiſh yellow Varniſh, mixed with a little Cinnabar, or Indian Lake, clouding it up and down the Work as nature requires; and touching it alſo with Varniſh, mixt with lamp or Ivory-black.
This done, Varniſh it 5 or 6 times over with the fineſt white Varniſh, or with fine Seed-lac Varniſh, letting it dry between every time.
Let it now dry a Week, and with Pumice-ſtone in fine Pouder, but rather fine Tripoli, and a wet Cloth, Poliſh it by gentle rubbing.
Laſtly, go over with it again 4 or 5 times with the fine White, or fine Seed-lac Varniſh; and when throughly dry, Poliſh it with Tripoli, and clear it with Putty and Oil, as before declared.
Yet another Tortoiſe Shell Japan:
Firſt lay a white Ground as before, and ſmear it over with Vermilion or ſome ſuch like, over which lay Leaves of Gold or Silver, as before taught, with Gum Ammoniacum, lacca Varniſh common Varniſh, Size or Glair.
This done, and being throughly dry, Shadow, cloud, and ſtain it, by ſome of the former Directions, according as the Reafon and Nature of the thing requires; ſtriking it over here and there with yellow Varniſh, or reddiſh yellow Varniſh, and red Varniſh mixed, with yellow Varniſh in perfect imitation of the Shell.