Making and Knowing
A minimal edition of BnF Ms Fr 640 in English Translation

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Lavender spike oil varnish

One must heat lavender spike oil and, as it begins to simmer, put in powdered sandarac gum so that it soon melts. And stir continuously over a charcoal fire until the sandarac is well melted, which you will know by taking a little of the said varnish on a plate and, if it is fat enough when you handle it with a finger, it is ready. And for one pound of lavender spike oil, you should put five ounces of ground sandarac. Some only put in four ounces but this is not as good, nor as fat. The former dries promptly. To avoid the trouble of polishing their ebony, framemakers varnish it with this. So do guitarmakers. This varnish is not as fitting for paintings as fine turpentine varnish, though it is good for the paintings’ moldings. When linseed varnish was in use, one would not commonly varnish the landscape of a painting because it would turn the landscape yellow. But with turpentine varnish one varnishes everywhere. Instead of sandarac, you can add to it pulverized mastic drop by drop or otherwise, and it will dry more quickly. If you want to varnish plaster or a wall, first put on your colle de retaille, very hot, because if cold it would not penetrate the wall at all. And when you would have put your varnish on, it would come off.

at left top margin of folio 004r

Aspic oil varnish is not as apt for colors as that of turpentine, because aspic oil eats the colors, since it is too penetrating.