Marble was used to create the bust of Madame de Sérilly. It is a relatively hard stone, pure white in its most highly-prized form, which needs to be quarried. Although the surface of the bust appears both smooth and highly polished, it would not have started off life like this. It would have been delivered to the artist as a rough-hewn block, which needed to be carved with hammer, chisel and drill and then polished. Think about what skills were needed to carry out this process: was the artist able to be spontaneous or did he work to a careful plan, for example using a model in terracotta or plaster?

Bronze is a hard water-resistant alloy of copper which can be highly finished, as can be seen in the bust of Veronese by François-Nicholas Delaistre. The artist would have modelled the bust in wax before it was finally cast in bronze. This is done by sculpting the image you require in a soft material, such as wax, then creating a mould of the image by encasing it in plaster and allowing it to harden. Further models are made using this mould, with a plaster or clay core over which is the wax ‘skin’ that carries the design. This new wax model is then encased in a thick clay casing, after which the wax is melted, leaving a void into which the molten bronze can be poured. Once it has hardened, the outer layer is removed and the portrait is revealed.

The two materials differ in many ways. For example, when working with marble you take the material away to create the image, whereas when working with wax (later bronze) you add the material. Also, they create a very different effect from each other. What do you think are the advantages and disadvantages of working in each material?

Chalks have been used to create the portrait of Jean-Victor, baron Besenval. At this time natural, rather than manufactured, chalks would have been used. The black chalk seen here would have been made up of carbon and clay whose compressed nature makes it particularly suitable for linear strokes as shown in this drawing. It contrasts particularly well with the natural white chalk also seen here (made from calcite and calcium carbonate) and which is really effective at highlighting the brightness of the armour and creating the illusion of  light shining towards the baron’s face.

Photography first appeared in the mid 19th century and had a great impact on portraiture. Not only did it offer a more accurate representation of its subject, but also it was vastly more affordable than more traditional painted portraits. Whereas portraiture was once the preserve of the rich, this new technology allowed middle class citizens to have their own images created. The medium therefore helped to change the status of portraiture. Photography has often been thought of as incapable of lying as it captures the unquestionable and exact likeness of the sitter and his or her surroundings. However, does photography necessarily show us the true reality of a sitter's personality, status and character? For example, do you think that the photograph of John Bowes is un-posed? It is also important to remember that early photographs would have needed a long exposure time and that the pose would need to have been held for a much longer period of time than nowadays.

How might you dress and pose for a photograph? You might want to be photographed, indoors or outdoors, in a grand setting or with a plain background. You might also include symbolic objects to create a fictitious environment or character for yourself. Indeed, we need to be just as critically aware when looking at photographic portraits as we do when looking at painting, embroidery or sculpture.