This lecture diagram on white wove Whatman paper shows four identical columns topped by an entablature, with the blocks of the wall behind the colonnade ruled in graphite pencil between one pair of columns, and strengthened with grey/black paint in the spaces behind three more columns. All the vertical lines are also strengthened with black paint, and some of the shadows in the bases are emphasised with browner wash to depict shadows. It is a copy of a lost original, as is Tracing of Guiding Lines
; Turner Bequest CXCV 161). There is no depiction of major shadows or their effects, in contrast to Tate D17142
(Turner Bequest CXCV 171) which illustrates this in several ways.
The present work was made by a copying process which Turner used to generate a limited number of copies from other lecture diagrams. It is rare that all or even most stages of the process survive, and there is no complete set in the Turner Bequest, since these materials were presumably transported to and used for a number of lectures over the years. He needed several copies so that he could if he chose illustrate the drawing of a single element such as a column alone, then later with perspectival lines going to a single point, or built up to a colonnade of identical columns, or used to illustrate the way to make a smooth column look three-dimensional by shading. He could also use such a colonnade to form part of the elevation of a building, as in this example, with the vertical fluting of one column illustrated, to show its portrayal as a three-dimensional form.
The process seems to have involved placing a blank sheet on a table, overlaying double-sided copying paper, followed by another blank sheet, another sheet of double-sided copying paper, and the image to be copied. In this case it would have been either a single column or a four-column colonnade, drawn in outline. Then he pressed down hard on each ruled line of the top copy with a sharp tool run against a ruler, and unpacked the paper stack to reveal one good and one pale copy, with little smudging on the ‘good’ sides. If necessary, he strengthened straight lines in the copies, which would both be identical and not reversed, and then he hand-applied the curved elements freehand as necessary, and/or painted the lines to make them bold enough to demonstrate to a large audience in a room lit artificially. Sets of copies identified thus far include: Building in Perspective
; CXCV 81) which is an upper copy of a lost original and A House in Perspective, Lecture Diagram 36
; CXCV 82), and Building
; CXCV 83) which are both lower copies of comparable originals; the original Column
; CXCV 91) which was used to make Tuscan Column in Perspective, Lecture Diagram 40
; CXCV 88) as the upper copy and Perspective Construction of a Tuscan Column, Lecture Diagram 41
; CXCV 90) as the lower copy; Tracing of Guiding Lines of Diagram of Capital, Tuscan Entablature Worked Out in Perspective
; CXCV 107) which was used as the original for the copies Capital, Tuscan Entablature Worked Out in Perspective
; CXCV 106) and Tuscan entablature
; CXCV 109); and the group discussed here.
This example provided excellent clues to the materials used in the copying process. Its lines are thicker than were drawn in surviving originals for other diagrams: the copying process broadened them, and left a halo of fluorescent material round each one, observable in ultraviolet light in the third column from the left, and its nearest blocks in the wall behind it. Painting for clarity in a lecture broadened them even more, and has hidden some of this evidence. Lamp black, clay-like silicate extenders (both identified by optical microscopy) and protein, which organic analysis suggests is either whole egg or egg yolk, made up the third column’s outline. This identification was made with a technique called Fourier transform infrared microscopy, which is done by comparing the results from known materials. It also detected the glue sizing present on all Turner’s papers.
Recipes exist for home-made copying paper, and evidence from three groups of the lecture diagrams – smudges of black material, occasional smears and the incised lines – suggests that a mixture of egg yolk or whole egg with cheap lamp black was generally involved. Thin paper dipped in such a watery solution, left to dry, and used once, would have worked. The copying papers were not used repeatedly, since all the copied lines are crisp and even, therefore clearly made from virgin copying paper that was so cheap it could be discarded after one use. This process could have been done at home, and repeated on a top copy if more copies were required. There is precedent for using eggs too: a fair proportion of the primed canvases Turner used while his father was alive and assisting him in the studio carry a priming made from lead white and whole eggs. Possibly Turner’s father assisted with the copying as well.
Soap, butter or linseed oil to mix with dry pigments in a variety of colours were also recommended in household encyclopaedias for copying paper: vermilion for red, carmine for reddish pink, blue bice for blue. The organic analysis technique used here would be able to distinguish soap, butter and linseed oil form the egg detected here. Some instructions suggested that dry pigment strewn over the back of the top copy, or soft graphite pencil shaded on, could work for generating a single copy. Turner’s lecture diagrams look too tidy and clean on the reverse side for these last methods to have been used, and the making of successive copies off one top copy would surely have led to smudging on the front as well.
How to cite
Julia Jönsson, 'Technique and Condition', January 2007, revised by Joyce Townsend, March 2011, in Andrea Fredericksen, ‘Lecture Diagram 8/2: Elevation of a Stoa or Portico (after James Stuart) c.1810 by Joseph Mallord William Turner’, catalogue entry, June 2004, revised by David Blayney Brown, January 2012, in David Blayney Brown (ed.), J.M.W. Turner: Sketchbooks, Drawings and Watercolours, December 2012, https://www.tate.org.uk/art/research-publications/jmw-turner/joseph-mallord-william-turner-lecture-diagram-82-elevation-of-a-stoa-or-portico-after-r1136468, accessed 22 August 2014.