[23] O Op. cit., pp. 46-48. Knowledge of the process seems to have disappeared completely during the 18th and 19th centuries. Hubert Herkomer, writing in 1892, believed that he had invented the white ground for the first time (Etching and Mezzotint Engraving, London, 1892, pp. 4 and 25).
[24] The etching is Hind 42. The drawing (Benesch 21, Hofstede de Groot 893) is in the British Museum. The black chalk has been confirmed (see footnote 25). It is also clear that the backing is not graphite, which would, of course, show up on a black ground as well as a white one.
[25] T The etching is Hind 187. The drawing (Benesch 758, Hofstede de Groot 896) is in the British Museum. Some scholarly misinformation has unfortunately been passed on for years. Münz, op. cit., vol. 2, p. 65, cites Jan Six ("Rembrandt's Vorbereiding ...," Onze Kunst, 1908, II, p. 53), who in turn cites the personal observation of A. M. Hind of the British Museum, to the effect that this drawing of Anslo was backed with black chalk. The two drawings had apparently not been lifted from their mounts in something like sixty years. In answer to the author's inquiry, Mr. J. K. Rowlands, Assistant Keeper, Department of Prints and Drawings, the British Museum, very kindly wrote: "I can now tell you about the backs of H. 42 and H. 187 [that is, the drawings for these two prints], which have now been lifted. The reverse of The Woman Bathing [Diana at the Bath] has the remains of black unrefined chalk upon it and the portrait of Anslo is backed with Ochre tempera. I think this news will interest you." I am most grateful to Mr. Rowlands and his staff for their trouble and kindness.
[26] An excellent example of this type of line is seen in the horizon lines on the left, which in this case were added only after several proofs had been pulled from the plate. The addition of these lines constitutes the difference between the recorded first and second states of this print.
[27] T The documents on this story were first published by Bredius in 1909 ("Rembrandt als Plaatsnijder," Oud-Holland, v. 27, pp. 112 f.) and have been frequently cited since then. The print is the portrait of Jan Antonides van der Linden (Hind 268).
[28] Confusion has arisen over a note, clearly in Rembrandt's hand, on one of his drawings (Benesch 1351, Hofstede de Groot 763, dated about 1654-55). The Dutch text is given in Benesch, op. cit., vol. 6, p. 374. It reads, "In order to etch ...," and gives a recipe consisting of turpentine and turpentine oil. This, of course, could not possibly be a mordant. Münz discusses it (op. cit., vol. 2, p. 14) and concludes that with the addition of mastic, this could be a kind of stop-out varnish. We are not likely to come closer to an answer for this cryptic inscription.
[29] Coppier, op. cit.
[30] Ibid., p. 117. Detail of plate for Hind 277, dated 1654.
[31] Bosse, op. cit., pp. 5 and 11. Vitriol is copper or iron sulfate, saltpeter is potassium nitrate, and alum is an aluminum sulfate salt. Bosse's other two acids are distilled pure vinegar (acetic acid) and a boiled mixture of vinegar and chloride salts. Both are relatively weak. My thanks to Dr. Robert P. Multhauf for his advice on 17th-century chemistry.
[32] Felix Brunner (A Handbook of Graphic Reproduction Processes, New York: Hastings House, 1962, p. 124), suggests that Rembrandt may have used ferric chloride, a weaker mordant, around 1640.