pg. 690 in Merrifield
from A Paduan Manuscript ("Ricotta per far ogni sorte di colori, etc.") dated to late 16th century.
94. A very clear varnish for pictures and paper alla Fiaminga
Take 7 ounces of highly recited spirit of wine, 2 oz. of sandarac, and 2 ounces of oil d'abezzo. The sandarac, which should be very clear, must be pulverized and put in a bottle with the oil d'abezzo, which also must be very clear. The spirit of wine must then be added, and the whole boiled gently ver the fire, until the whole is dissolved, keeping the mouth of the vessel well closed, that the spirit of wine may not evaporate. The varnish must be strained into a glass vase, leaving the impurities at the bottom. When it is used it must be put into a majolica cup, the picture also must be heated, and the varnish applied with the pencil."