This unrolling was begun in very cold weather; if the temperature had been a little higher, nothing of this kind would have taken place. The picture now shows no sign of defect or injury, and is in perfect condition. By substituting ceresin, a paraffin obtained from ozokerite or earthwax, for crystalline paraffin, the chance of cracking is obviated. The ceresin, which should have a melting-point of 150° or 160° Fahrenheit, constitutes a safe substitute for the beeswax commonly employed in Gambier Parry's Spirit Fresco Medium.
Foggia, October 15, 1895.
You will be surprised to get a letter from me with an Italian superscription; I am writing thus early before my return to save time. When I was in Venice the other day, Van Haanen spoke to me, with approval, of a certain vehicle, of which I had already heard before vaguely, the invention of the French painter, Vibert. You probably know of it, as the subject of media has occupied you. There are, it appears, three forms of this medium: the vehicle for painting, the medium for painting into in retouching, and the final varnish. As far as I understood Van Haanen in a hurried conversation—he was a little vague—the painting medium contains no gum, only, he seemed to think, petroleum and oil; I assume that in the final "vernis" there is gum of some kind.
I am perfectly satisfied with Bell's medium and fresh turpentine for the very little use I make of vehicle in painting; but there is always the difficulty of the final varnish in the Academy. I don't like risking mastic or copal so soon on work which contains nothing but oil (and if I ever do use a little, I put poppy oil with it), and the result is that I generally varnish with Roberson's medium, which is safe, but I fear a little inclined to yellow in time.
Now what I want you kindly to tell me, my dear Church, is the exact composition of the three Vibert media, and your opinion about the safety of using all three in the prescribed order; and this I should like to know on my return at the beginning of November (hence my haste in writing), and also whether I can safely use these vehicles on work begun in my usual medium.
It is just possible you may not have heard of the Vibert vehicles; if so, I would ask you to be so kind as to obtain (of course at my expense) a bottle of each of the mixtures and to test them carefully.
A line to say this has reached you would find me at the Hôtel Royal Mazzeri, Via 20 Settembre, Rome.
With kind regards and anticipated thanks.
Hôtel Royal Mazzeri, Rome,
October 22, 1895.