The three loose folios below are from the Khamsa of Amir Khusraw, an illustrated Persian manuscript in the Chester Beatty Collection, dating from 1485 and produced in Herat. The Khamsa is a collection of five classical romances from the Persian tradition. The romances featured in these particular folios are Shirin and Khusraw (left and centre), and Laila and Majnun (right).
Persian illuminations are meticulously crafted paintings on paper. The Islamic-style paper used is surface-sized and burnished heavily to provide a smooth, glossy surface for the calligraphers and painters to work upon. The painting is then built up in layers of pigment, burnished between applications in order to create opaque, jewel-like lustrous colours. However, the layered structure of the pigment strata can cause problems with flaking and losses, whilst the characteristics of certain pigments used can cause specific problems: lead white has a tendency to flake, copper and lead- based pigments can cause corrosion and discolour, whilst silver tarnishes quickly (visible in the river in the image above right).
The materials and techniques used therefore mean that flaking pigments can be a problem inherent in this kind of art. Conservation of such objects involves examining the folio methodically under magnification in order to identify flaking, cracking, and areas of loss, and to ascertain whether there is a risk of further losses being incurred. If at-risk areas are found, the problem pigment can be ‘consolidated’ – this means applying tiny amounts of adhesive to strengthen the bond between paper and pigment. Using a very fine brush, tiny amounts of a cellulose-ether based adhesive are introduced next to the crack or lifting flake. The paper substrate should then absorb the adhesive, and using capillary action drag it through the fibres, so that the adhesive locates itself between pigment and paper without the conservator having to touch the pigment layer directly.
This image shows the extent to which the flakes curl away from the paper, and how blue underpainting is visible where losses have occurred. An additional problem was that the small amount of moisture from the adhesive appeared to be causing some mobilisation of the purple pigment (a reaction that has not been seen before), suggesting the presence of an unstable organic red in the make-up of the purple. This has prompted further research and reading on my behalf into the purples used in Persian manuscripts. Unfortunately, another method attempted (using a nebuliser to introduce a very fine mist of consolidant) did not appear to stabilise the area or secure the lifting flakes either, so in this instance it was decided that the folio is too fragile to be displayed, as further handling and movement could result in pigment loss. Further investigation into what the purple pigment might be may allow us to reassess the treatment of the folio at some point in the future.
Conservation of the other two folios was much more straightforward. Per 163.120 (Leila and Majnun in the desert) is now on display in The Arts of the Book gallery at the Chester Beatty Library.
All images © courtesy of the Trustees of The Chester Beatty Library