Portrait miniatures: Common susceptibilities

by Satomi Kitano

RCA/V&A Postgraduate Conservation Programme
Specialism: Conservation of European Portrait Miniatures (MA)

Portrait miniatures were first painted in the sixteenth century. These early miniatures were painted in watercolour on vellum, usually stuck down onto a piece of playing card. The common problems associated with these miniatures are flaking paint and paint loss, which is often due to the use of thickly applied paints that contained low amounts of binding media. Blackening of lead white pigment and tarnishing of silver (which was used as a pigment) are also quite common in these periods. Eighteenth and nineteenth century miniatures are usually painted in watercolour on ivory. Ivory is susceptible to changes in humidity and can warp or crack when restrained in a tightly fitting locket. Crystal formation, flaking paint and craquelure in paint layers are also often found on ivory miniatures. All miniatures are prone to mould growth because of the micro-climate created in their lockets and frames. However, mould is particularly common with miniatures on ivory. These miniatures were often painted with watercolour containing larger quantities of gum Arabic, as a binding medium, which can be a source of food for micro-organisms.

V&A No. 304-1890 Untitled, formerly attributed to Samuel Cooper.

V&A No. 304-1890 Untitled, formerly attributed to Samuel Cooper. 17th century. Watercolour on vellum. This image shows historical damage to the lead white paint in the face – the blackened areas are due to oxidation from pollution (red circles shows the affected areas). Micrograph x10.

V&A No. 23-1975 Portrait miniature of Queen Elizabeth I, by Nicholas Hilliard.

V&A No. 23-1975 Portrait miniature of Queen Elizabeth I, by Nicholas Hilliard. Circa 1586-1587. Watercolour on vellum stuck to playing card. The simulated jewels in Tudor miniatures were normally created using silver as a paint. The diamonds on the sitter's hair have tarnished due to oxidation (circled). Paint loss and blackened lead white can also be seen on this miniature. Micrograph x10.

V&A No. P. 22-1928 Untitled, by T. C. Thompson. 19th century.

V&A No. P. 22-1928 Untitled, by T. C. Thompson. 19th century. Watercolour on ivory. Efflorescence of crystals on the paint layer. These crystals consist of magnesium phosphate, which is a natural constituent of ivory and were caused by high humidity. The miniature was already in this condition when acquired by the museum in 1928. The right hand side of this miniature has been treated using micro-crystalline wax to change the refractive index so that the crystals become less visible.

V&A No. Evans.74 Untitled, by Rosalba Giovanna Carriera. Circa 1710. Watercolour on ivory.

V&A No. Evans.74 Untitled, by Rosalba Giovanna Carriera. Circa 1710. Watercolour on ivory. This is an image taken under ultra-violet light. Areas of historical retouching fluoresce differently from the original paint layer allowing us to pinpoint old losses/damage (red arrows show these areas).

V&A No. Evans.74 Untitled, by Rosalba Giovanna Carriera. Circa 1710. Before conservation.

V&A No. Evans.74 Untitled, by Rosalba Giovanna Carriera. Circa 1710. Watercolour on ivory. This image shows an area of flaking paint and paint loss. This is a common problem with watercolour on ivory miniatures due to lack of adhesion between paint layer and support. This photograph shows the condition before treatment. Micrograph x20.

V&A No. Evans.74 Untitled, by Rosalba Giovanna Carriera. Circa 1710. After conservation.

V&A No. Evans.74 Untitled, by Rosalba Giovanna Carriera. Circa 1710. This image shows the same area of the paint layer after consolidation. Micrograph x20.

V&A No. P. 8-1934 Untitled, by Peter Paul Lens. Mid 18th century. Before conservation.

V&A No. P. 8-1934 Untitled, by Peter Paul Lens. Mid 18th century. Watercolour on ivory. Miniatures from mid - late eighteenth century are often painted on very thin sheets of ivory (the thickness is often less than 0.2 mm) and they are prone to warping and cracking.

V&A No. P. 8-1934 Untitled, by Peter Paul Lens. Mid 18th century. After conservation.

V&A No. P. 8-1934 Untitled, by Peter Paul Lens. Mid 18th century. Watercolour on ivory. After treatment, which included consolidation of the cracked ivory support and minor retouching to the background.

Fading due to light exposure is also a common problem with most miniatures because of their relatively thin paint layers. For this reason display light levels are controlled using visitor-operated lighting systems. Treatment options are decided with ethical consideration and carried out using appropriate conservation materials and techniques. A miniature conservator has to have knowledge of a wide variety of materials such as paints, parchment/vellum, ivory, paper, glass, metals, enamels, wood, textile and others as they are highly complex objects.