Phoebe Anna Traquair responded to the location and the moment rather than work out all the details in advance. Few sketch designs for her work exist, and most of those are for enamelling and embroidery. A publicity photograph of c.1897 shows her chalking an outline of her composition directly on to the north wall of the north chancel aisle.
In 1900 National Gallery of Scotland director James Caw wrote in The Art Journal that Traquair ‘wrought direct upon the walls … she waits until an idea shapes itself in colour and line in her mind’s eye, and then transfers it to the walls at once, thus retaining the vividness and freshness of the conception.’ The scenes in the nave were worked particularly quickly over a rougher plaster finish than found elsewhere.
Traquair’s use of colour and texture give the decoration a vivid, ‘musical’ quality. Her oil paints were diluted with turpentine, which, when applied to the dry, white-painted plaster surface, gave the colour a translucency parallel to that of watercolour on paper. The final beeswax coating was burnished by hand to give a silky soft sheen and protect the paint from the climate. Where gesso was also applied, it sometimes contained rough string to provide additional texture and vitality.
There are no documents written by Phoebe Traquair that describe her working methods. However, her technique was described in detail in a lecture given by Frank Morley Fletcher, the first Director of the Edinburgh College of Art, in 1909. Wooden surfaces were prepared with a thick ground of zinc white base mixed with chalk and linseed oil applied with a wide brush. Plaster walls have two layers: a rough, white coloured lime-based first coat made of lime mixed with course sand, with a smoother pinkish coat made of lime mixed with sand and tinted with iron oxides. The roughness of the surfaces adds a vibrancy to the colours and increases the reflective qualities of the paint.
According to Frank Morley Fletcher the paint was “oil colours in tubes, thinned by a medium of beeswax dissolved in turpentine”. In addition to colour, Phoebe Traquair applied metal leaf and raised work, or pastiglio, to the surface, which, combined with the lively roughness of the preparatory layers, gives the decoration a richly textured quality. ‘Silver’ gilt is, in fact, aluminium leaf. According to Morley Fletcher: “The varnish used was of a good copal carriage variety; finally a wash of wax and turpentine was applied and polished by hand to a dull eggshell finish”. Discoveries during the restoration work showed that this description is accurate with the exception of the preparatory layers which were found on analysis to be lead white, not the zinc white described by Morley-Fletcher.
Pigments identified by analysis in 1999 included terre verte, viridian, ultramarine blue, iron oxide earth pigments, carbon black, possibly vermilion. Some pink, red and yellow lakes were tentatively identified. Further samples taken at the beginning of the restoration confirmed these results, and a cobalt blue has also been identified. The paint is so transparent that it is possible to see how the artist sketched out the design onto the surface before painting, and how frequently she altered the design slightly in the final painting. In one instance on the ceiling of the south chapel she sketched the arrangement of two figures on a small scale before painting over the sketch.
The speed at which Phoebe Traquair worked may be seen in her painting of the timber framing mouldings. Here the paint has been put on quickly, with little concern for neatness of finish, since the overall effect is all that would be seen from the ground. There are several instances where the artist “touched up” her painting. The most obvious cases are where she has blocked over areas in white paint. This may be seen clearly on the lilies on the south side of the south chapel ceiling.