Technique and condition
The white wove drawing paper was made by Edmeads and Pine. The paper is entirely covered by paint, and any under-drawing is impossible to discern. The trees were created using washes of yellow, blue and black rather than mixing the colours directly together. Numerous mixed greens were used in the foreground, made probably from indigo and different brown ochres. The rather muted highlights were probably painted with yellow ochre for the sunlit leaves and vermilion for the red details, while a mixture of thin white and Mars red was used to paint Kensington Palace. The swans could have been created with meticulous, successive lifting of paint with a very fine brush dipped in water, but an easier method would have been to use a stopping-out technique with gum water. This involves painting a near-invisible swan onto the blank foreground with pure gum water, then letting it dry. The whole foreground could then be worked rapidly on top, without taking any care to leave the swan unpainted. Then the whole sheet, once dry, could have water poured carefully over the swan area to reveal the reserved white area in crisp outline, ready for finishing if necessary. The sky was painted last, likely with indigo. This fine-grained pigment might not have survived the washing stage of the stopping-out process that could have been used to facilitate making the swan. It was in any case Turner’s habitual practice in both watercolour and oil, to complete the sky last.1
See also Nicola Moorby and Ian Warrell eds., How to Paint like Turner, London 2010, pp.102–3.