Relevant Mayerne recipes.

Or Coloeur [gold color]

P. 262 in book Lost Secrets of Flemish Painting / Ms. P. 155

{marginal note} M. Adam Susinger. Gold on blue. Paint your frame or other work with white lead ground in oil and immediately spread azure over it by applying the dust everywhere with a brush, let it dry. Do the leadwork with or couleur, let it dry 4 or 5 days, lay gold or tin over it and varnish over that without touching the azure.

White lead as desired, according to whether you want it light or dark, if possible umber burn red and very desiccating and brown red which is burnt yellow ocher. Rind these very long and impalpably fine together with common linseed oil, and consider that the paint will be very thick. Each paint should be ground alone and then mixed together on the palette. Then a drying oil made with litharge is added so that the paint is not too thick and can be worked on and easily applied with a brush. Thus do your lea work and the layout.
Let it dry or 3 or 4 days, the longer the better. Even when the paint is well dried out, it does not stop being a little sticky and the gold adheres very well on it. This is cut to the required size and placed on a horn handle, or taken with a knife, and when the horn is removed, [the gold] remains stuck to the oil, upon which it is pressed with wool. The trick in this consists in grinding he paints thoroughly and in the thorough drying o the oil. {marginal note} Idem
With the same [gold paint] tin foil and copper can be made fast. To maintain its luster and to prevent the air from spoiling it, it is necessary to lay a very light water proof varnish over it.
As soon as the gold is made fast, remove the excess with wool or with a hare’s paw.
Note, if you want to do your layout with a gold color on black or another dark paint, first the black should be mixed with glue and applied, and on that do your leaf work with oil. Let it dry as above, lay on the gold, remove the excess and finally varnish [the whole thing]. Then the black will look like ebony. Common varnish with a little spikenard oil for drying (is suitable for this).