*3.3. Painting Process*

It is noteworthy that the VIS and NIR photography of the paintings did not detect the presence of the preparatory underdrawings. However, Liu Kang probably studied the subject matter by small-scale sketching prior to painting the composition on the canvas. For instance, a watercolour sketch of *Breakfast* from the Liu collection reveals an early idea of the composition for the canvas painting *Breakfast*, which was executed in the same year (Figure 15). Technical evidence from the *Countryside in France*, *Village scene*, *Breakfast*, and *Self-portrait* indicated that the artist approached the canvas with a clear concept of the general composition, which was established with rough brushstrokes usually of a black paint (Figure 1b,d,g and Figure 2e).

**Figure 15.** (**a**) Liu Kang, *Breakfast*, 1932, watercolour, 23 × 29 cm. Liu Kang Family Collection. Image courtesy of Liu family. (**b**) Liu Kang, *Breakfast*, 1932, oil on canvas, 46 × 54 cm.

The next step of the painting process involved a gradual colouring in of the outlines of the forms, providing the base for further work, as seen in *Countryside in France* and *Landscape* (Figures 1b and 2b). This method, known as *ébauche* (coloured sketch), was a common practice among Impressionists [55]. Analyses of the brushstrokes revealed that the middle-ground buildings of *Countryside in France* and the foreground house and a tree of *Landscape* were painted first. Then, the artist continued building the colouristic structure around these main subjects. The sky in *Countryside in France* was probably sketched at the end, after the background greenery was completed. Both sketches were conducted in local, vivid colours. A minimal suggestion of light effects observed in the sky of *Countryside in France* was achieved by the increased transparency of the colour, allowing the white ground to show through. The rapid development of the composition during the initial painting phase was facilitated by a few factors observed in *Countryside in France*. The small size of the painting support (number 10) reduced the time required to cover the surface with colours. The use of the absorbent or semi-absorbent ground with the ability to draw the oil from the paint accelerated the drying of the paint layer [9,56]. A thin application of colours mixed with lead white promoted the rapid drying of the paint layer. The presence of the signatures and dates indicates that the artist envisaged the coloured sketches as a completed exercise.

The further painting process can be observed in *My landlady, Madame Normand* (Figure 2f). Here, the artist intensified the colours of the main subject and built-up details with thicker paint. The advanced light effects were achieved by the increased opacity of different tints of white paint. Although the green background is sketchy and transparent, the artist's signature and date on the painting indicate that he considered the artwork as completed.

Liu Kang's variety of methods of handling the paint show constant self-development. In *Autumn colours*, his application of the paint using a small brush in short, vigorous, and descriptive paint touches reflects his attention to detail (Figures 1a and 16a). A daring adoption of parallel brushstrokes in *St Gingolph, Lac Leman, Switzerland* is reminiscent of van Gogh's style (Figures 2a and 16b). The structure of the paint layer with attractive touches is achieved by contrasting juxtaposition of greens with reds and yellows with blues. However, another painting, *Landscape in Switzerland*, shows some modification to this painting method. While the background depicting lake, mountains, and sky was conducted with directional touches, the foreground buildings and fields are depicted by coloured patches (Figures 1c and 16c,d).

**Figure 16.** Details showing different types of brushwork in: (**a**) *Autumn colours*; (**b**) *St Gingolph, Lac Leman, Switzerland*; and (**c**,**d**) upper and bottom parts of *Landscape in Switzerland*.

The analyses of the paint structure of *Landscape in Switzerland* revealed the hardened brushwork beneath the upper layers, suggesting that the painting, including the signature and date, was executed in a wet-on-dry technique, as illustrated by the microscopic images (Figures 10 and 11b). Hence, two distinct painting sessions can be identified, where the second session, according to the artist's date and signature, could have been in 1930, at least six months after Liu Kang's trip to Switzerland. A combination of wet-on-wet and wet-on-dry paint applications was detected in other examined paintings, suggesting that the artist did not attempt to complete the work at one sitting and sometimes worked further on the composition after the initial painting was dry. This tendency could be a result of Liu Kang working on several paintings during one session as documented in the photograph from 1929 taken in Saint-Gingolph, Switzerland. Interestingly, one of the paintings seen in the photograph appears to be unfinished; hence, it can be hypothesised that the artist tended to apply finishing touches later (Figure 17).

**Figure 17.** Archival photograph of Liu Kang during a painting session in Saint-Gingolph, Switzerland, in 1929: (**a**) Detail of the photograph showing a painting, probably unfinished; (**b**) Liu Kang Family Collection. Images courtesy of Liu family.

A good example of a painting executed rapidly in a single sitting is *Village scene*. In this artwork, there are significantly few details while the general artistic expression is achieved by directional and highly textured brushwork combined with solid colours (Figures 1d, 5b and 18c,d). Meanwhile, *Boat near the cliff* is characterised by a synthesis of colours and forms achieved by the broad and flat application of the paint (Figure 1f). Although the painting appears to be spontaneously and rapidly executed, the analyses proved a wet-on-dry execution, suggesting that later modifications were conducted over previous partially hardened touches.

**Figure 18.** Details showing the incorporation of the colour of ground in the painting process in: (**a**) *Boat near the cliff*; (**b**) *Still life with books, Paris*; and (**c**) *Village scene*. Initial compositional lines are exposed in: (**c**,**d**) *Village scene*.

During the painting process, Liu Kang experimented with incorporating the white colour of the ground layer with other paint colours reflecting inspiration from Modernists' techniques [9,57]. A good example is *Countryside in France*, in which the colour of the exposed ground was utilised for depicting the main building (Figure 14a). In contrast, the ground in *Landscape* remains exposed between the patches of applied paint, giving the artist a chance to make adjustments of colour and form (Figure 2b). In *Boat near the cliff*, the ground was used as a highlight and colour in its own right to describe foamy water (Figure 18a). However, *Still life with books*, *Paris*, and *Village scene* exhibit a new experiment with a white ground. Liu Kang enhanced the brilliance of the painted scenes by exposing bright accents of the white ground through the spaces between directional brushstrokes (Figures 5b and 18b,c). This painting method seems to support the notion that the artist sometimes skipped the colour sketching and confidently applied the colours after establishing the general composition with dark outlines. Moreover, to moderate the monotony of a methodical brushwork, the artist creatively produced effects of the broken flow of the paint, by dragging a loaded brush across the textured ground layer (Figures 5b and 18a–c) [9].

An interesting example of the artist's inventive way of utilising the colour and texture of the painting support is *Self-portrait* (Figure 19). As it was executed on the reverse side of an earlier composition, the brownish canvas made it particularly well suited for providing colouristic unity among the mixed yellows and browns. Moreover, the colour and texture of an un-primed canvas were skilfully exposed to give an impression of the back side of a depicted painting.

**Figure 19.** Detail of *Self-portrait*, showing the incorporation of the colour and texture of the painting support in depicting the reverse side of the painting in his artwork. The inset detail shows the structure of the canvas.

Another feature common in the examined paintings is the presence of a strong contour. The lines accompany the painting process from the sketching until the final stage, and they play a crucial role in the aesthetic of the paintings giving greater definition to the forms of the subjects. In *Village scene,* some of the initial compositional lines describing the highest distant hilltops as well as the shapes of the houses are still visible through the paint layer (Figure 18c,d). In the final stage, the artist usually reinforced the outlines of the subjects with a dark paint composed mainly of bone black with ultramarine and/or Prussian blue, as identified in *Village scene* (sample 13, 14), *Landscape in Switzerland* (sample 18), and *Breakfast* (sample 14).

### *3.4. Reusing Earlier Paintings*

The evidence collected from five examined paintings revealed that Liu Kang had a practice of reusing earlier, unwanted compositions or utilising their reverse sides. For example, a visual inspection of the painted edges of the *St Gingolph*, *Lac Leman*, *Switzerland* revealed the presence of colours to be unrelated to the final image. The raking light and RTI examination of *Autumn colours* pointed out the surface brushstrokes that skip over the more complex texture of the underlying paint scheme. Subsequent transmitted NIR photography conducted with a camera facing the back of the painting revealed a presence of a still life composition that had been created in the vertical orientation. Further XRR analysis confirmed that the underlying painting depicts plants in flowerpots (Figure 20).

A visual examination of *Breakfast* provided some indications of another composition underneath. For instance, a different paint scheme was observed in the areas that were not completely covered by the current painting. Moreover, the final paint layer is characterised by several dark paint strokes that do not correspond to the present composition. They are visible on the green table top and red background, probably due to decreasing hiding power of thinly applied upper paint layer (Figure 21) [58]. This feature is similar to the reported case study of *Seafood* by Liu Kang, in which his hidden self-portrait was discovered beneath [8]. The NIR photography of *Breakfast* rotated 180◦ revealed a view that could be interpreted as a riverbank with trees.

Besides the aforementioned examples of paintings over discarded compositions, Liu Kang also utilised the reverse sides of earlier paintings. *Self-portrait* and *Portrait of a man with his pipe*, *Paris* are examples of artworks created directly on un-primed canvases. The artist's practice of reusing unsatisfactory compositions or utilising their reverse sides could have been motivated by a temporary shortage of materials or by financial constraints.

**Figure 20.** Images of *Autumn colours* rotated at 90◦ anticlockwise and photographed in: (**a**) VIS; (**b**) RTI; and (**c**) transmitted NIR executed with camera facing the back of the painting, then cropped to remove the strainer bars, inverted horizontally, and reproduced with the same relative scale; (**d**) XRR. The images revealed paint features of hidden still life painting with plants in the flowerpots.

**Figure 21.** VIS (**a**) and NIR (**b**) images of *Breakfast* rotated at 180◦. NIR reveals the hidden view of a riverbank with trees.
