During the 1750s Reynolds began to experiment increasingly with his painting technique, employing an unusually wide range of pigments, oils, and varnishes. While these experiments often resulted in brilliantly coloured and highly textured works, the instability of certain pigments (notably red lake, carmine, and orpiment) and his incautious combining of incompatible materials resulted in fading and cracking. These shortcomings did not appear to concern Reynolds, who, when challenged, retorted, ‘all good pictures crack’ (Leslie and Taylor, 1.112–13). At this time Reynolds also began to tender out the painting of costume in his portraits to professional drapery painters, notably Peter Toms and George Roth, who also painted drapery for Hudson. By now Reynolds was extremely busy, producing over 100 portraits a year. And as he became more successful so his prices rose accordingly. In 1753 he charged 48 guineas for a full-length portrait; by 1759 the price had risen to 100 guineas, and by 1764 to 150 guineas (Cormack, 105). Reynolds often worked a seven-day week, save for a hiatus in the months of July and August, when his fashionable clientele deserted the city. From 1755 until he ceased painting in 1790 Reynolds noted appointments with his sitters in small diaries, or ‘pocket books’, of which most have survived (RA; Cottonian Library, Plymouth), and which provide detailed information on his working life and social engagements.
By the late 1750s Reynolds had established a systematic method of determining the attitudes chosen for portraits, keeping a portfolio of engravings after his own and other artists' works from which sitters could choose and adapt poses. The first mezzotint engraving after one of his paintings was Lady Charlotte Fitzwilliam, made by the Irishman James MacArdell, who before his death in 1765 engraved thirty-seven plates after Reynolds. Subsequent engravers included James Watson, John Dean, John Raphael Smith, Valentine Green, and his own pupils, Marchi and William Doughty. These engravings, as much as the paintings themselves, were responsible for promoting Reynolds's work at home and abroad, and were exhibited by engravers in their own right, occasionally even prior to Reynolds's original paintings. Reynolds, who did not charge engravers to copy his works, recognized the importance of prints, allegedly stating after MacArdell's death, ‘by this man I shall be immortalized’ (Waterhouse, 1973, 20).
By the mid-1760s Reynolds's painting style was emulated by a number of his contemporaries, notably Francis Cotes and Tilly Kettle. Reynolds's own relations with his fellow artists were generally cordial, although he seldom became close. An exception was the Scottish portraitist Allan Ramsay, who exerted a considerable influence over Reynolds's own work, and whom Reynolds befriended in 1757. As Horace Walpole memorably remarked, ‘Mr. Reynolds and Mr. Ramsay can scarce be rivals, their manners are so different. The former is bold, and has a kind of tempestuous colouring; yet with dignity and grace; the latter is all delicacy’. He added somewhat unfairly, ‘Mr. Reynolds seldom succeeds in women; Mr. Ramsay is formed to paint them’ (Walpole, Corr., 15.47). As his portrait of Georgiana, Countess Spencer, and her daughter reveals (1760–66; priv. coll.), Reynolds was capable of conveying the same air of intimacy and naturalism which pervades Ramsay's portraiture, although he possessed a directness to which Ramsay seldom aspired.