The Importance of Understanding the Materials and Techniques of Portrait Miniatures

By Alan Derbyshire, Conservation Consultant | May 2023

As a conservator of portrait miniatures it is vital to understand how miniatures were painted and what materials were used in their making. This knowledge serves to clarify how they can best be conserved for future generations.

Alan at work. © Victoria and Albert Museum, London

Miniatures from the 16th and early 17th centuries were painted in watercolour and bodycolour on vellum, usually stuck down onto a piece of playing card. The vellum is fine animal skin taken from aborted calves, which is hairless and therefore smooth. Bodycolour is simply watercolour made opaque by adding a higher ratio of pigment to the gum Arabic binder than with normal transparent watercolour. This bodycolour can be clearly seen in areas such as the thickly painted lace and ruffs of Tudor miniatures. Flaking is quite common in these areas as the paint layer dries out over time. Consolidation – using an inert adhesive - can arrest this problem.

In the 17th century, artists began to stick the vellum down into tablebook leaf rather than playing cards. Tablebook leaf is card which has been coated on both sides with a thin layer of gesso (a mixture of chalk and animal glue). These leaves were made into books so that merchants could write on them in pencil or a metal point – hence the name. Occasionally, with these miniatures, the gesso layer can flake causing the vellum to delaminate. Again, this problem can be solved with careful consolidation and re-attachement of the vellum.

The most significant change in materials occurred at the beginning of the 18th century when Rosalba Carriera (1675-1757) began to use ivory as a support rather than vellum. These early ivory miniatures are quite stable as the ivory is quite thick but as the 18th century progressed, the translucency of the ivory was exploited by cutting it more thinly and hence it was stuck down onto white paper or card to stabilise it and to retain its ‘whiteness’.

The thin ivory can react to changes in humidity and temperature so it is important to keep one’s miniatures in relatively stable conditions – for example away from radiators and from direct sunlight. If miniatures are kept locked away in safes for security reasons be sure to check them with a magnifying glass. Careful handling and regular checking will ensure that your miniatures remain in optimum condition.