P.S.—Of course I only use cadmium red when I want a very deep orange in drapery or sky—nothing could replace it.
Feb. 2, 1885.
Here is a little problem: I thought all burnt colours were ipso facto sound. Roberson tells me that burnt white (Chremnitz do.), a lovely colour like ivory, plays most amazing tricks, darkens and lightens again in rapid succession. WHY? When you are in Long Acre make him show you his samples.
Thanks for your letter. I don't use any particular colours other than those you mentioned in your lectures, although I thought of trying deep yellow madder again; I used to like it very much. I suppose you have the list—it is a very long one—of Edouard's colours. Smith is his agent here (14 Charles Street, Middlesex Hospital). I use one or two colours (Tadema I think all) from Mommen's in Brussels; his burnt sienna is superb. Asphaltum would reward study; it was universally used by the Venetians, and seems never to have cracked with them. I am very glad that you are steadily pursuing your collection of specimens and experiments, which I hope will by degrees become an exhaustive one, and of infinite value to the profession. Grounds, too, will deserve much attention.
Kindly tell me whether there is any harm in putting a thin coat of mastic, softened perhaps with a drop or two of oil, over works finished quite recently but begun a year or more ago? If I understand rightly, cracking is caused by atmospheric action through the back of the canvas, by distension of underlying partially soft paint and, consequent disruption of the upper, harder layer of varnish. If the first painting is a year old, is it not tough enough to resist the atmosphere, and is it not anyhow pretty safe when the canvas is backed?
I suppose "Mutrie yellow" is quite safe alone and mixed with other pigments?