Painting enamel azure in oil
This is a secret that is hardly known to common painters. Some take the most delicate they can & crush it with ceruse, which binds it, and next prick with an awl in several places the area they want to paint with azur d’esmail, such that the oil enters & leaks in, & does not cause the azure, which in itself is heavy, to run. Others lay the panel flat & apply the azure on it, which is also done à destrempe. The main thing is to crush it well on marble, and before that, to have washed it thoroughly. Some grind it with thoroughly with an egg yolk & then wash it in five or six lots of water and lay it on not with a painceau, which would be too soft, but with a broisse highly softened & bent, & laying it on thickly as if one were applying it with a trowel; settling down it evens out and flattens. I have experienced that crushing azur d’esmail with egg yolk & then washing it in several lots of water is good, although it loses a little of its vividness in the crushing of it. I have also washed it in several lots of water &, when it had settled a little, I removed the water, still q blue, with a sponge and squeezed it into another vessel thus where it settled, & from the residue I had the ash, flower and subtlest part of the azure without crushing it, which is the best, for in the crushing of it, it loses some of its color. Those who make it in Germany compose it like enamel, in large pieces which they pestle, & pass through several sieves & wash.
To make azures beautiful, they wash or soak them in a rock water, as they call it; it is a water distilled from mines where azure or vert d’azur is found, which distills naturally through the mountain’s veins or is distilled with an alembic par from >mineral stones of azure or copper.
Azure ashes are only good for landscapes because they die in oil. Only true azure lasts. Azur d’esmail cannot be worked if it is too coarse. Try it, therefore, on the fingernail or the oil palette. If it happens to be sandy, do not crush it except with the egg yolk or, better yet, wash it in clear water & with a sponge remove the colored water after it starts to go to the bottom, and in this manner you will extract the quite delicate flower, which will be easy to work with.