At different times in her career, Hepworth’s paintings and drawings anticipated, coincided with or followed from changes in her sculpture. Shortly after she began to use sheet brass and bronze in 1956, she developed a new abstract idiom in oil paintings and pen and ink drawings. One of her first uses for metal sculpture was to exploit its tensile strength, and she used this to create looping structures in bronze as with those of Curved form (Trevalgan) (1956) [BH 213]. Some paintings and ink drawings made in 1957 and 1958 have constellations of black lines that resemble those twisting metal forms.

In these years Hepworth experimented with the organic unevenness of a loaded pen or brush, extending black lines through multiple changes of direction and applying them with autographic freedom in scrubbed, smoothed and blotted marks. In her painting Rhythmic forms, the application of black lines is closely comparable to contemporaneous pen and ink drawings. A sense of motion is apparent as the lines repeatedly move up and down the full length of the narrow tableau in continuous strokes of a fine brush. This vertical motion is contrasted by a coarse, richly textured underlayer of paint, applied with horizontal strokes of a broad brush. Before the artist added washes of colour and the pale, centrally positioned circle, the painting was photographed by Studio St Ives at Hepworth’s Trewyn Studio in April 1958. It was exhibited in this state at Gimpel Fils in June 1958, where it hung beside a version of the brass and string sculpture Orpheus. Closely related works made titular allusions to ‘the nest’, ‘high summer’, ‘spring’, ‘fantasie’ and ‘dance’, and Rhythmic forms resonates with all such connotations.

Describing the ‘vigorous gestures of black paint’ in Hepworth’s paintings and drawings of 1957 and 1958, the curator Chris Stephens has proposed that ‘they suggest a vegetal bursting forth of energy entirely consistent with her interest in organic forms and processes.’ Eleanor Clayton has argued that the ‘thick, black, calligraphic marks’ displaced the ‘intricate, “strung” lines’ of preceding paintings and drawings. But there is considerable continuity between these different types of mark-making, and the swiftly applied black markings of Rhythmic forms relate to the stringed patterns and raised, wing-like forms that occur in contemporaneous works such as Winged figure I (1957) [BH 228]. In two pen and ink drawings directly related to the ‘winged figure’ type, Hepworth used the same kind of charged, calligraphic lines to describe both the metal ‘wings’ of the form and the strings that criss-cross in front of it. The fluid, interchangeable character of these black marks, at once sculptural and string-like, was one of the reasons they appealed to Hepworth at this stage of her development.