The first is colour for thin gilding. You take equal proportions of sulphur, tartar well-pounded, and salt, grinding them separately, then you take half a part of cuccuma[178] and you mix them all four together. When you have the gilded parts well cleaned & scratch-brushed, as I described above, you take a little urine of children or boys, put it tepid into a clean pipkin and apply it with hog sables, and the virtue of the urine and the sables will remove any dirt or grease that may have come on the gold. This done, you get a copper cauldron, or mayhap an earthen pot, & in one of the twain, after filling it with boiling water, you put your colour composition & stir it well up with a rod or a bunch of twigs till it is thoroughly dissolved and mixed. Then you tie a bit of string, long enough to hold it by, on to the work, and dangle it in for such time as one might say an Ave Maria; after this you pull it out and dip it into a vase of clear cold water. If it has not taken colour enough you put it back again into the hot water, and so on for two or three times till it be sufficient, minding, however, not to let it stay in over long or else it will turn black and spoil the gilding. This colouring matter is the weakest one can make and can only be used for one turn.
FOOTNOTES:
[178] More correctly, ‘curcuma’: turmeric root.
CHAPTER XXVIII. A RECIPE FOR MAKING ANOTHER SORT OF GILDING COLOUR.
Take red chalk,[179] verdigris, saltpetre, vitriol,[180] and salts of ammonia, but half as much of the first as of the other ingredients; take each by weight, and pound each separately; and be careful to pound them very fine; when pounded stir them up in clear water to the consistency of a paste, and while you are stirring see that you go on grinding them up till all the particles are well blended. This done, you must put them in a rather big vase because the composition bubbles up; and mind that the vase has a glazed surface, or better still be of glass, and let it be corked. In order to put the colour on, your work must needs be thickly gilded, or else it will turn black, for this colour is very powerful. But if it be sufficiently strongly gilded the work will colour beautifully. The colouring stuff is applied with a paint brush, but you must mind not to touch the silver or you will black it. Painted over in this wise you set your work to the fire, give it a good steaming and dip it into fresh water, but you must mind not to overdo the steaming or the gold would be eaten away and not hold.
FOOTNOTES:
[179] Matita rossa.
[180] Vitriuolo: probably green vitriol, i.e., sulphate of iron.
CHAPTER XXIX. HOW TO MAKE A THIRD GILDING COLOUR FOR VERY THICK GILDING.[181]
Take the work you want to gild, & in the same way as described above, clean it[182] and gild it, then skilfully dry it; don’t be particular as to drying it too much, only let it be free of all quicksilver, then clean it again lightly and heat it over live embers. Whilst it is in process of heating spread on it a kind of wax which I will describe below.