This painting is in oil paint on canvas measuring 1033 x 775 mm (fig.1). The support is made from two pieces of plain woven linen joined together at a horizontal seam just below the sitter’s sash, approximately 160 mm above the lower edge (fig.2). The larger piece, with 9 vertical and 11 horizontal threads per square centimetre, is coarser than the smaller, which has 14 vertical and 13 horizontal threads. The absence of any disruption in the ground as it passes over the seam in the X-radiograph suggests that the join was present from the inception of this painting. Faint indications of cusping on the upright edges suggest that originally the painting may have been wider – perhaps as much as 100 mm.1 The absence of cusping at the top and bottom edges may mean that more canvas was removed from there at some point in the past. The original stretcher is not extant and there are no bar marks in the picture to indicate its construction.
The ground on both pieces is light beige colour. It looks very chalky in cross-section (figs.3–4). It was applied by being scraped hard into the canvas weave, just skimming the tops of the threads. Its brittle nature has led to extensive, small, oval-shaped losses of ground on the canvas tops all over the painting, worst in the dark areas (fig.5). The ground contains marine chalk, gypsum, lead white, yellow ochre or sienna, glassy particles, Cologne earth and black, bound together in non-heat bodied linseed or walnut oil.2
Infrared reflectography reveals a few sketchy lines in what might be black crayon in his right shoulder and further, more elaborate fine lines describe ornamentation in the helmet (fig.6).
There is substantial, fully modelled dead colouring beneath the whole composition, as follows: opaque brown beneath the mustard yellow background; shades of opaque beige and brown beneath the buff coat; opaque, dark flesh-tones beneath the pink, scumbled paint of his right hand (fig.7); lilac-grey beneath linen (fig.8); dark grey beneath the white highlights of the breastplate (fig.9).
There appears to be an alteration in the lower right foreground: opaque thick yellow and white paint can be seen under magnification beneath the stone colour of the ledge. The handle of the pistol was altered at an early stage of painting (fig.10).
For the final painting Dobson mixed opaque colours on his palette and worked them wet-in-wet on the dry underpainting, adding detail and glazes on top later. His brushwork was rapid and expressive (fig.11). The taffeta sash was laid in with an opaque, light coloured brick red, after which a lighter mixture containing white or yellow was added wet-in-wet for the highlights. Then a cooler brown was added to the shadows of the folds.
Finally the entire area was glazed with a red lake, which has survived only in the troughs of the paint film (fig.12). The brick red and light red colours contain lead soap aggregates at the surface (fig.13) but these are not visible in the shadows.3
The flesh tones were mixed on the palette from lead white with opaque reds (vermilion and a variety of ochres, some purplish in tone), large agglomerates of yellow ochre and large quantities of black. The bluish white highlights of the metallic helmet and breastplate were mixed from ultramarine, black and white (fig.14), in contrast to the white linen, where lead white with black was used instead. The sky is lead white with smalt, and the darker, greener area that was applied on top of it was mixed from blue verditer, black, lead white, yellow ochre and smalt. For the dark, mustard yellow background he made mixtures of lead white, yellow ochre, umber, smalt, black, gypsum, Cologne earth and indigo.
The smalt mixtures in the sky have discoloured from blue to a yellowish tone. In 1973 the painting was cleaned at the Tate, revealing the helmet that had been hidden beneath overpaint. An old, double, glue lining was removed and replaced with a wax-resin lining. The varnish is the modern synthetic resin, Paraloid B-72.