Van Hoogstraten’s varnish

Ingredients

turpentine oil, mastic, oil

Preparation Steps

Original Recipe Text

The recipe, dated September 23, 1711, involved heating mastic in a pan (p. 280). Eikelenberg modified the original recipe by reducing the initial quantity of turpentine oil by a fourth to avoid squandering it during the 'arduous evaporation exercise' (p. 267). When oil was added to the mixture, it appeared to curdle, which Eikelenberg attributed to the coldness of the oil solidifying the mastic (p. 280). He observed that the oil mixed better with the turpentine when warm. He also emphasized preventing 'any flame' from reaching the pan with mastic to mitigate fire hazards (p. 280).

Evidence

"I noticed that the half-prepared varnish appeared to curdle. This I believe was due to the coldness of the oil solidifying part of the mastic; while also the oil mixed better with the turpentine."

Remarks

Eikelenberg observed that when the varnish was put into a glass bottle while cold, a 'whitish sediment had formed' (p. 280). He judged this varnish to be 'not as good as the varnish of gum copal [...] but better than if sandarac is added' (p. 280).