CXI. The receipt of the fine Venetian lake.

Valuable Secrets concerning Arts and Trades:
or Approved Directions, from the best Artists, for the Various Methods...
Printed by Thomas Hubbard,
Norwich, 1795
Chap. V. Secrets concerning colours & painting.

§ VIII. Preparations of colours of all sorts for oil, water, and crayons.

1. Take one pound of good pearl ashes. Put it in a large copper; then, pour over it six gallons of spring water. Should you not have any spring water, take river, but no pump water. Let the pearl ashes soak thus twenty-four hours, after which, set the copper on the fire, and boil it for one quarter of an hour. Then filter this lye through a cloth jelly-bag, and receive the filtration in a stone pan.

2. If, at first, the lye did not run quite clear, filter it till it does; and then, changing the pan onty under neath, pour what ran thick in the first pan in the bag again. When all is new filtered and clear, put it in the copper again, which must have been previously well washed, and set it on the fire to boil. When it does boil, throw in two pounds of fine scarlet flocks, which you boil to whiteness. Then filter again this lye tinged with scarlet colour, in the before-mentioned jelly-bag, and press well the flocks, that there may not remain any colour in them.

Observe, that in order your bag may serve you both for the lake and tincture, without being at the trouble of cleansing it, you must not filter through it the second lye in which the scarlet is. For should you pour this lye from the copper, directly into it, the scarlet flocks would undoubtedly run with the lye, which would give you an infinite deal of trouble to get out of the bag, after the filtering of the tincture. And the least bit of it would entirely spoil the lake. Therefore, to avoid all these inconveniences, strain your second lye either thro' a cloth suspended by its four corners, or through another bag by itself.

1. While the tincture is filtering, get the copper well scoured, cleaned, and wiped dry. Put the filtered tincture in it. Dissolve, over the fire, and in a copper or glazed earthen sauce-pan, half-a-pound of Roman alum in one quart of spring water. Then strain it quickly, and, while warm, pour it in your tincture, keeping stirring all the while, and afterward, till all the froth has quite subsided. Boil, next, all together for the space of half a quarter of an hour. Then throw it in the same bag that filtered your first lye, and receive the filtration into a clean stone pan.

4. Besides this; boil again, in another quart of spring water, half a pound of Fernamburg Brasil wood, cut and bruised in an iron mortar. Strain it through a cloth, and pour it, along with the above dissolution of Roman alum, in the jelly-bag, and stir it to run all together.

5. After all is run out of the bag, throw in again half a pint of quite clear and pure spring water.

6. When nothing runs any more of it of the bag, the lake is left in it. Take it out with a box spoon, as we said in the preceding article, and spread it on plaister flat stones, three fingers thick, and about half a soot square, covered with white cloth of the same size. For should there be no cloth on the plaister, the lake would stick to it.

Note. It often happens for the first water which runs out of the bag to be muddy, and to carry some lake along with it. But you must continue filtering till it comes bright and clear. Then, taking off the pan from underneath, and substituting another, you put that muddy liquor into the bag again. - Should, by chance, the filtration continue to run red, as it sometimes happens; you must still keep filtering the liquor through the bag, till it is clarified.

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