A Technical Study into Bridget Riley’s paintings Fall and Hesitate

In 1988 when discussing the physical construction of her paintings and how they were made, Bridget Riley stated that ‘everything about the painting is there to be seen on the actual surface. The paintings themselves answer this question ... I know that might sound as though I am evading the issue, but it is in fact true’.1 Detailed examination of two of Riley’s paintings from the early 1960s, which were selected as case studies as part of an international research project, supports the artist’s assertion.2 While much of the construction process can be seen with the naked eye, technical investigation and scientific analysis carried out on Fall 1963 (Tate T00616) and Hesitate 1964 (Tate T04132) between 2022 and 2025 have revealed further insights.3

Since the 1960s, Riley’s drawings, paintings and wall paintings have challenged how simple pictorial elements – squares, circles, ovals, lines and curves – can be perceived through sequence and repetition.4 Simple shapes recur and are manipulated to their extremes before they collapse into a new form and no longer retain their original characteristics.5 The progression of these shapes creates movement and flux. Riley initially explored this tension in black and white, before introducing further complexity by adding in greys, and later, colour. Greys disrupted the alternating binary of black and white and added a sense of tempo that could be ‘accelerated … or delayed’.6

Fall and Hesitate epitomise the artist’s methodical, precise and restrictive parameters and enable the spectator to experience stability and instability, certainty and uncertainty, and to consider what can be recognised in the paintings beyond the identifiable forms. Drawing on Riley’s influences and working methods during a period of radical change in art production, this article sheds new light on the physical structures of these two paintings and how they were made.

Path to abstraction

In the summer of 1960 Bridget Riley travelled to Italy where she attended the Venice Biennale with the artist and writer Maurice de Sausmarez, her romantic partner at the time.7 Riley was captivated by the work of the Futurists at the Mostra storica del futurismo (Historical Exhibition of Futurism), admiring artists such as Umberto Boccioni, who captured movement within a two-dimensional plane by drawing on pioneering chronophotography from the 1880s.8 These artists created a dynamism of successive spatial movements, giving the viewer the impression of progressing through the picture. During another trip to Venice the following year, Riley was caught in a sudden downpour of rain. Water droplets bounced from the white and black piazza tiles, dissolving and merging their pattern. Then, as the heat of the piazza surface caused the rain to evaporate, the clarity of the tiling patterns returned.9 This experience undoubtedly influenced the conception of Movement in Squares 1961 (fig.1), one of Riley’s earliest experiments with disruption and return.

Movement in Squares depicts a chequerboard pattern of black and white squares that compress into rectangles, arranged to give the impression of gradually bending into an off-centre vertical apex and then flexing back again, not quite back to their original form. The viewer cannot passively observe the surface but is drawn into the space as the shapes change and cluster together. As one approaches, the shapes take on different ratios and the viewer’s perspective changes, while the use of contrast between black and white within the sequencing enlivens an involuntary static charge that resonates back and forth to create the illusion of movement on the surface. Credited as Riley’s breakthrough into abstraction, Movement in Squares could also be seen as a form of chronography or a measure of time as the micro-adjustments of the square makes them appear to move in and out of being, flickering between black and white in rectangles that narrow before expanding again. The perceived flux between rigid structure, interference with form and the return to equilibrium became a major theme in Riley’s paintings in the early 1960s.

Riley’s artistic training began in 1946 at Cheltenham Ladies’ College under the supervision of Colin Hayes.10 In 1949 she attended Goldsmiths College, where under the tutelage of Samuel Rabin Riley took life drawing classes in which she learned to work methodically and uncover the structure within form.11 Riley’s education taught her to look, to balance her analytical and empathetic perception to understand form. In 2020 she stated:

Studying the human form enabled Riley to comprehend arrangement, shape and line. Thinking about structure allowed her to build up methodical and technical paradigms in her practice that extended beyond painting figures and landscapes. This facilitated her move into abstraction.

In an interview in 2019, Riley recalled her first meaningful encounter with the effects of contrast and opposition within a painting:

This experience culminated in the artist’s first abstract painting, Kiss 1961 (fig.2).14 By introducing two lines of white against solid black, one straight and one curved, which almost touch one third up from the lower edge of the painting, Riley divided the previously monochrome surface and the tension this created excited and inspired her. This awareness and sensation resulted in a period of intense creative activity between 1961 and 1966, where Riley occupied her first small studio in Warwick Road, West London, while she also worked part-time as an illustrator with an advertising agency until 1962–3.15

The 1961 paintings paved the way for Fall and Hesitate. Retaining the stark contrast of black and white, the artist developed the two forms of line in Kiss into a repeated curved line in Fall, where the vertical structure incorporates a horizontal resonance as the bends become tighter. This recalls the off-centre suspense in Movement in Squares, which, along with Fission 1962 (fig.3), can be seen as a precursor to Hesitate. The black circles in Fission yield into tight ellipses, as they do in Hesitate, and as the ellipses border the point of erasure and become slits, the surface appears to cave in, like a fissure. As the distance between the black and white forms in Movement in Squares and Fission is compressed they seem to optically merge, and as the demarcation between the two colours blurs, an optical grey midtone emerges.

In the spring of 1962 Gallery One, London, staged Riley’s first solo exhibition of her black and white paintings, which included Kiss and Movement in Squares.16 International recognition came quickly thereafter, with Riley’s inclusion in the group exhibition The Responsive Eye at the Museum of Modern Art, New York (MoMA) in 1965, where Hesitate was on display. Her painting Current 1964 (fig.4) featured on the catalogue cover; comparable to Fall, the painting depicts alternating black and white lines where the curve tightens just above the centre horizon to create static charge or interference.17 The Responsive Eye centred on artworks that were labelled ‘entirely abstract’ by the exhibition’s curator, William Seitz.18 The exhibition resulted in the increasing popularity of the term ‘op art’, which had been coined the previous year in an article by Jon Borgzinner for Time magazine.19 ‘Op art’, shortened from ‘optical art’, can be defined as abstract art from the early 1960s which aimed to stimulate the eye through optical effects achieved by manipulating space, contrast and colour.20 Seitz, however, preferred the term ‘perceptual abstraction’, as did Riley, who, having worked in advertising, was familiar with contrived means used to grab attention and alert to her art being debased by simplistic terminology. For Riley, op art was a reductive dogma that ‘smacks of gimmicky selling slogan’ and she disliked the idea that her paintings could be diminished to an optical experiment.21 She disassociated her work from the term.

The illusion of movement created in Futurist art through the interpenetration of planes and overlapping of fragmented shapes differs to the motion conceived in op art. In an increasingly mechanical age, Futurist painting emphasised creating an impression of speed and simultaneity through multiple viewpoints depicting recognisable modern objects or events. Whereas op art was not considered an attempt to depict an act or object in motion, but rather to exploit contrast and pattern to deceive the eye into perceiving a virtual movement. In op art the surface was considered static and motionless, even with the movement of a form, until the viewer triggered the optical movement as co-producer by stepping into the painting’s range. The movement itself does not physically happen on the surface of the picture, of course, but is in the perception that our eyes and brain manifest. While Riley initially considered the spectator part of the work itself, an active component in creating the moment where the painting ‘took place’, she later concluded that an interior space held a depth between painting and viewer, so instead the painting could be ‘inhabited’, one’s eye moving around in it, and escaping beyond it’s two dimensional borders and penetrating into this interior space that the painting and viewer occupy simultaneously.22

Riley’s distinct patterns also captured commercial interest.23 The dressmaker and art collector Larry Aldrich appropriated Riley’s painting Hesitate, which he owned between 1964 and 1980, to design a fabric that he revealed to her just before the opening of the MoMA exhibition.24 A dress made from the fabric featured in LIFE magazine in April 1965 (fig.5).25 Riley was distraught. This was not an isolated event, and her paintings were both copied directly and adapted for fabrics that filled shop windows in New York and beyond.26 The sincerity and artistic integrity of the exhibition felt compromised to Riley, and she tried to take legal action to prevent the commercialisation of her work.27 This was an unsettling period for her, and she stated: ‘They just lift them wholescale, and on the most superficial level. So nothing has unity. I’ve yet to see an Op fabric which is wearable. I think they’re ugly beyond belief ... I feel like I've been invaded’.28

Compositional development

The late 1950s and early 1960s saw many changes in art production. Traditional artist materials were being used alongside commercial and construction materials such as self-levelling household paints. These paints had a flow and viscosity that reduced the retention of brushstrokes creating smoother, even surfaces. Some artists separated their work conceiving or designing an artwork from physical execution with the expansion of artist’s workshops and employment of assistants. Additionally, artists were not necessarily standing at the easel but working flat, on floors, tables and even tilted revolving surfaces. Riley embraced these opportunities, using new materials, engaging assistants and working flat.

Riley used commercial items that could be readily purchased and were not specifically designed for creating art.29 She welcomed this as a form of ‘anti-art‘ statement.30 This extended to her use of household paints, as well as T-squares, geometry compasses, templates and other specialised tools which would have enabled precision and repeatability and were widely accessible at the time.31 Riley worked flat on a white adjustable-height table made by her friend and fellow artist Peter Sedgley.32 Parallels can also be drawn between the draughtsmanship and technical skills Riley developed in her work at the advertising agency and the techniques she employed in her paintings.

To develop ideas Riley would begin by drawing on plain or graph paper, working in pencil and gouache paint, creating multiple images simultaneously.33 Those showing promise were developed into full scale paintings, without variation.34 There is no strict chronology to the development of her work in any given year; rather, she pursued multiple directions concurrently. Riley’s drawings on paper involved much experimentation.35 Some of these works explored the mutation of a singular shape or the tonal organisation of grey progressions, others were annotated with number sequences, speeds and movement directions, and specified revisions and her reflections. Drawings remain an essential part of Riley’s process.

After working exclusively in black and white, Riley introduced neutral grey – grey that contain black and white only – into her paintings in 1962.36 This allowed Riley to increase the planes of movement and tempo in her compositions, as seen in one of her first paintings to include grey, Black to White Discs 1962 (fig.6).37 For Riley, there are two types of tempo, one being the overall tempo within the painting through the progression of form, and the second being the different speeds of movement within those forms achieved through selecting tones between the boundaries of the achromatic, black and white.38 Riley employed grey tones to facilitate ‘fluid, intermediary modes, which would allow me to break through the straight alternation’.39 This was achieved in Black to White Discs through a single grey tone per vertical column, progressing from lighter to darker grey and back to lighter tones resulting in an off-centre fade while the form of the circles remained constant. Riley credits the use of greys with creating ‘visual time’, building tempo through acceleration and deceleration, which she has described as beats, ‘five beats, seven beats, twenty-four and so on’, gifting a pulse or a second rhythm to the composition.40

Two different tempos are visible in Hesitate, where the circles on the lower edge progressively take on an elliptical form that is narrowest one third from the top, before returning to the original circular shape at the top of the painting, creating the illusion of progressive vertical movement. This is juxtaposed with a diagonal sense of sequence created by the gradually changing grey tones.41 The intervals between the greys, which vary across the picture, show a faster tempo on the lower-left vertical via fewer tones close together before cascading into a softer, gentler tempo with increased numbers of shades in the lower-right horizontal. This creates a dynamic energy within the painting, drawn into multidirectional movements. Riley noticed that the fluidity of grey had the capacity to bridge the contrast between light and dark, and keep a door open for colour.42 From 1965 she introduced sequenced, or coloured, greys by adding red and blue to her palette, expanding tonal variance to include warm to cool.43 From 1967 colour was present within her paintings in its own right.

Studio, materials and construction

Assistants have been involved in the production of Riley’s work since 1961, and have included family members, such as her mother.44 By removing her own hand from the execution of the final painting Riley distinguishes between the creative work that she put into her drawings and the requisite ‘craft’ process for a painting’s execution.45 Rather than turning to industrial processes, she employed other individuals to paint her surfaces. Riley explained in 1991 that when employing assistants she ‘wanted the actual content of the paintings to come through unchecked by any kind of touch, so that you could see the strength or weakness of something without any barrier’.46 She has said she is ‘not at all interested in any sort of liberation from the working process; quite the reverse. Holding myself at a certain distance enables me to be more engaged, not less’.47 The studio atmosphere that Riley nurtured for over sixty years has seen highly skilled professionals expertly carrying out her work with impeccable execution.48

Looking closely at the surfaces of Riley’s paintings, one can nevertheless see the application methods employed, such as brushstrokes. However these are not defining features, nor are they apparent at a distance. It is only as the viewer advances to look closer that hints of the hand at work can be seen, revealing features which come into full view under magnification or in raking light.49 Riley therefore achieves her aim of allowing the composition to dominate while having created a unique, handmade painting rather than an industrially produced object. This remains important to the artist: ‘I want my works to be perceived as made things. And I like them to be well made: I’ve never wanted any kind of mechanised look’.50 While much of the construction process can be seen with the naked eye, scientific analysis and technical imaging have made it possible to examine the less evident nuances of her paintings.

Painting Fall and Hesitate

Fall and Hesitate were both made using poly(vinyl acetate) (PVAc) emulsion household paint on hardboard. Riley chose to work on board because it offered a firm surface with some resistance and lends itself to working flat (fig.7).51 Hardboard offers a number of other advantages for painting; it is easily cut, available in large sheets, does not have a grain (unlike wood), and can be processed or post-treated to be less responsive to changes in temperature, humidity and to moisture.52 For both Fall and Hesitate Riley used wet-processed hardboard, comprised of wood fibres and a slurry of water that has been compressed together under heat. The manufacturing process can result in a different finish on each side; a rough, textured side caused by the imprint of mesh enabling steam to escape during production, and a smooth side formed against a flat plate. Riley painted on the smooth side and did not prepare the hardboard prior to painting.53 Hardboard was readily available for artists to buy in the 1960s in standard size sheets, corresponding to the size of Hesitate. Fall, however, is larger and Riley must, therefore, have sourced a custom-made, oversized piece.54 The panels are edged with softwood timber to increase the depth of the paintings and were supported with a second piece of hardboard attached to the reverse to create a rigid and stable structure.55

In the early 1960s Riley was painting with household emulsion (waterborne) paints. At the time, acrylic paints were not commercially available in the United Kingdom, and alternatives such as oil paint did not produce the matte, uniform finish Riley was seeking.56 Oil also required longer to dry between applications, which slowed down the painting process. Poly(vinyl acetate) paints were developed in the 1950s, with several brands producing household paints and later, artists’ colours.57 Riley achieved ‘the strongest contrast obtainable between black and white’ by turning to two different manufacturers, selecting Della Robbia for the white paint and Ripolin for the black paint.58 As well as their rapid drying, excellent flow quality, clarity of colour and covering power, Riley said she liked the classical connotation of the name Della Robbia, referring to it as ‘housepaint with a classical name’, and she perceived the paint to have a porcelain-like quality.59 Like many artists of the time, Riley was also aware of Picasso’s use of Ripolin and said, ‘if he had used it, then it was probably the best around’.60 She celebrated the fact that ‘there was an element of doing something that was not Beaux Arts’ in her choice of these commercial products, explaining ‘I was not going to have what we thought of in England at that time as a piece of “fine art“… I had considerable pleasure in making a hardboard panel, using household paint’.61

The paints for Fall and Hesitate have been thoroughly analysed.62 Both paintings were created using poly(vinyl acetate) emulsion-based paints. The white pigment was identified as primarily titanium white and the black pigments as a mixture of iron oxide (Mars) black and bone black. Analysis confirmed that the two paints were mixed to create the greys in Hesitate. Extenders (white solids like chalk) and plasticisers were also present in the paint films. These were added by manufacturers to adjust and control the paint’s optical or physical properties, all of which are congruent with this period of twentieth-century paint production.63

Fall

Fall (fig.8) was the first of Riley’s works to enter Tate’s collection. It was acquired in October 1963, approximately three months after it was made.64 Fall depicts a series of repeating curves that form a vertical wave, with softer, broader diameter curves at the top of the painting that move into a tighter, dense series of smaller curves compressed together towards the lower edge. In this section, the vertical curve takes on a horizontal resonance with lateral energy. There is no beginning and no end to the wave, drawing the eye across the painting in all directions, with no stable starting or finishing point. Alternating black and white banding repeated through the consistent curve completely fills the hardboard support.

Similar works by Riley include Current and Crest (fig.9), both from 1964, in which different curves pulse in other ways with banding that is parallel to the main verticals dominating the compositions in the centre.65 In these three paintings Riley uses the simple structural device of a series of curves to simulate contraction, expansion and movement in two planes, with repetition of the same structure generating visual unrest. Paintings from the same year, such as Polarity (fig.10) and Untitled 1 (Warm and Cold Curves) (fig.11), insert neutral and sequenced greys adding further motion, with dissipating and receding forms, as well as a sense of differential banding achieved through shading.

Fall is painted on an oversize piece of Royal Board, 3-millimetre thick wet-processed hardboard, measuring 1410 by 1402 millimetres. There are two manufacturers’ stamps on the textured hardboard reverse (fig.12).66 The depth of the painting’s overall structure is 38 millimetres, made from softwood battens which are present along all outer edges, with two vertical internal wooden cross members and one horizontal. The softwood battens are attached to the hardboard reverse with adhesive on the back and nailed with hardboard pins from the front around the perimeter and across the centre (fig.13). The hardboard supports were manufactured by the art technician and transporter John Holt, to Riley’s specification.67

The front of the painting is primed with white paint, built up in a series of layers which were lightly sanded between applications and applied in multiple directions.68 In a paint cross-section from Fall, the laminate structure of the multiple layers of PVAc emulsion titanium white paint are not visible, indicating the layers were applied in quick succession (fig.14).69 Overall, the white layer measures between 50 and 400 microns thick across the painting. The white paint was diluted before the initial coat was applied, and fluid drips are visible, having run over and down the side edges, in keeping with being created flat (fig.15).70 When asked about the paint rheology and the flow of PVAc when painting, Riley stated that the consistency should resemble ‘single cream and double cream, but not butter!’71

To construct the composition, Riley drew a curve by hand which was transposed to a hardboard template by Peter Sedgley.72 Using pencil, the composition was drawn onto the white primed hardboard working along the template. The repeated lines are spaced approximately 5 to 6 millimetres apart, with the distance judged by eye. Traces of pencil can be seen on close examination along some of the edges of the lines (fig.16). Black paint was then applied on top of the white in the alternate wave forms to create the composition, leaving the priming layers to form the white stripes. The black paint was applied with rounded brushes, requiring regular dipping into the diluted paint, as shown by the varying transparency evident on close examination (fig.17). The black paint was similarly applied with the painting flat, to control flow and prevent drips.

There is a fluidity to the application, with longer strokes used where the curves are looser and the radius curvature is greater, and shorter strokes when the resonance tightens and the curve’s radius shrinks. Variations in paint texture are visible as small areas of rounded soft impasto – thick paint or texture in a painting – are evident where two brushstrokes were applied side by side or over each other, creating overlaps where the paint is slightly higher and more densely coloured. The black ends at the edge of the picture plane and does not extend around the sides. After painting the black lines, small adjustments in white paint were applied on top to ensure the crispness and uniformity of the black lines, or where there was too much variation in the hand application of the black. These adjustments are creamier in tone and have a slightly granular surface texture compared to the priming layer. However, they are original to the painting, were applied at the time of construction and possess the same chemical composition as the paint used for the white priming (fig.18). Detectable in ultraviolet light, the locations of these adjustments were mapped and show minor revisions occurred across the painting (fig.19). Fall is unvarnished and has never been framed. It is signed ‘Riley ’63’ on the lower right-side edge in thinned black paint.

Hesitate

Hesitate (fig.20) was made the year after Fall and purchased by Tate in 1985.73 In Hesitate Riley explored the progression between circles, which she considered the ‘most restrictive form of all‘ given that a circle cannot be broken, and ellipses.74 Hesitate is one of six works made in 1964 of varying dimensions and executed on hardboard in which Riley explored this transition, alongside the placement and tempo of tone through successive neutral greys extending between light and dark. In Hesitate, Where (fig.21), Pause (fig.22), Loss (fig.23), Metamorphosis and Remember the composition is rotated or the apex of the elliptical form repositioned and the grey tones are arranged differentially to create six unique sequences with varying degrees of convulsion, oscillation and vibration. Unlike in Fission, which creates a sense of vertical movement by playing on the tension of changing form in the horizontal through black progression against the white background, the shifting grey tones used in this group of paintings give the illusion of movement occurring vertically, horizontally and diagonally.

To create Hesitate Riley began with a preparatory study (fig.24).75 She drew a pencil grid on a piece of plain paper to determine the spacing of the shapes. The distances between the horizontal pencil lines vary vertically, adapting to the changing shapes from circle to ellipse, although they are consistent and evenly spaced in the perpendicular direction where the forms repeat consistently. The work on paper suggests that Riley drew the grid before adding the shape outlines in pencil in a rhythmic on/off, leaving the adjacent alternating areas blank to create gaps which form the background in the final composition.

The gradients of grey are documented on the sketch. Thirteen grey tones are numbered in intervals of two from ‘0’ to ‘24’, one shade per circle along the top and bottom edges. These are spaced sequentially to move in one direction, left to right, pale to dark. However, in the vertical direction there is greater variation in the progression, similarly starting at ‘0’ on both left corners and finishing at ‘24’ on both right corners. With 19 shapes in the vertical axis, however, Riley moved from ‘0’ to ‘24’ and back again to ‘0’ on the left, and the reverse on the right. This was achieved by doubling some of the grey gradient intervals, as seen from the lower-left corner vertically, where sequencing ‘0, 4, 8’ jumps in increments of four until ‘24’ – thus increasing pace and movement – followed by returning to a slower two interval pace to reach the top left corner. This subtle change in sequencing creates movement by accelerating and then slowing the tempo of the resulting curves, forming the perception of the crest of a wave. Although there are some variations to the gouache or watercolour shades in the preparatory drawing (also influenced by the discoloured paper), the tones clearly match those of Hesitate.

There is no pencil grid for Hesitate, as can be seen on the sketch.76 Rather, marks were made on the white paint surface to indicate the position of compositional elements in relation to each other. These can be divided into three types (fig.25). The first marks are short linear pencil marks visible to the naked eye, drawn with a ruler along the top and bottom edges to demarcate where the painted circles should cease and leave a white perimeter (fig.26). Two vertical columns (‘16’ and ‘17’ from the left, numbered as per the sketch) have two complete columns of ellipses drawn very lightly in pencil. There is no alternating on/off spacing and no gaps, as seen in the sketch, instead the ellipses are drawn consecutively next to one another and almost touch. These are the second distinctive planning action. The ellipses were drawn around commercial templates, their pencil lines visible at some grey painted edges (fig.27) and seen in their entirety in infrared reflectography (IRR) as they sit on top of the white surface (fig.28). The unpainted but drawn ellipses are less easily discernible to the naked eye as the pencil was significantly lighter in application, as evidenced by high resolution digital microscopy (figs.29 and 30).

In columns ‘16’ and ‘17’, all the spaces for circles, which comprise the top row and lowest ten rows, have holes at their centre from a pair of compasses whether they are painted or unpainted (see fig.26). The holes are the third distinguishable arrangement mark. The circles were not outlined in pencil at all, but the holes create fixed points from which to measure between each circle to ensure accurate spacing. The centres of the circles and ellipses were marked on pieces of tape and adhered to the painting to help position the composition initially.77 The compasses left very small pinprick holes in the surface of the hardboard and all would have been marked prior to painting (figs.31–33). With two completely marked columns, the rest of the composition could be built from this anchor position. On occasion, there are two compass points for one circle where painted: perhaps the first touch marked the location of the circle and the second occurred during the painting of the outline (see fig.31). The painted outlines of each circle were made with the pair of compasses holding a ruling pen filled with the chosen paint colour. The tape was removed once the shapes had been positioned. Painting could then begin.

Hesitate is an almost square-format painting which is also executed on 3-millimetre thick hardboard, also likely to be Royal Board and sourced from John Holt. Slightly smaller than Fall at 1067 by 1121 millimetres, with an overall depth of 28 millimetres, softwood battens are present along the outer edges and internally placed along the diagonals as seen in the X-radiograph (fig.34).78 The original hardboard backboard is still present, adding rigidity and stability to the structure (fig.35). Hardboard pins were used around the front perimeter of the painting and on the reverse along the edges, as well as through the diagonal cross-braces for extra attachment on the back only, to reduce potential distortion.79 As with Fall, the surface was primed with white paint applied in multiple directions using a wide brush with the painting laid flat, built up in layers until the desired opacity was achieved (fig.36). In a cross section some variation in the thickness of the layers of white are visible (fig.37).

Riley mixed the tones of grey by eye, all of which were blended ahead of time and placed in individually labelled pots so that the range of tonal progression was known prior to painting.80 In Hesitate, grey tones are made from white and black only, confirmed by analysis and consistent with Riley’s practice at this time.81 Riley explained that with the outlines painted first, the shapes would be infilled with paint fairly quickly afterwards as to revisit an area would create variations in the application.82 The outlines of the ruling pen are pronounced in raking light (see fig.36), while brushed application for the ellipses is indicated through a curved outer edge and multidirectional strokes in the centres (fig.38).

Like Fall, Hesitate is unvarnished. Throughout its display history Hesitate has been exhibited in two frames, most commonly in the non-original L-section white-painted wooden frame in which it was acquired by Tate.83 On occasion it has also been displayed in a Perspex ‘over frame’ but it is currently displayed unframed, according to Riley’s wishes. The painting is signed ‘Riley ’64’ on the lower left side edge in thinned black paint.

Both paintings are stable and in sound physical condition, with minor areas of historic cracking around the nails only and good paint adhesion across the structure. Years of display had resulted in an accumulated yellow-grey soiling layer on the surfaces which rendered them dull and matte. As part of the GREENART project, the paintings were successfully cleaned with innovative methods and tailored cleaning solutions that preserved these pressure- and solvent-sensitive, porcelain-like surfaces. These treatments enabled the contrasts and juxtapositions in both paintings to regain their crisp, definitive edge and the energy of the paintings to have been enlivened once more.84

Conclusions

Detailed study of Fall and Hesitate has confirmed that Riley’s method of creating her immaculate and exacting paintings is accessible for all to see, as the artist herself stated.85 However, the visibility of the technique does not interfere with the effect of viewing the work as a whole. Tempo, flux, repetition, sequence are conceived through a limited palette of black, white and then grey tones. The constants in Fall and Hesitate are also sites for departure, allowing the observer to experience the picture plane as dynamic. Riley is encouraging us to actively engage with her works, where the viewer may see a void one moment and a full, rich, crowded visual field the next. The act of looking has a progression, therefore, independent but in addition to the progressions seen in the paintings themselves.

Through technical analysis of the paintings, examining each layer in turn and revealing their cumulative effect, we acquired new perspectives on the subtle three-dimensionality of these works. A better understanding of the materials, painting surfaces, vulnerabilities and construction processes enables us to appropriately preserve these unique works of art, in this case for the first time, now and into the future.