Although many of the fragmentary sources of Medieval Polyphonic Music were damaged by contemporary vandalism the most common cause for loss (and in fact survival) was the use of dismembered parchment manuscripts to reinforce later bindings. A number of fragmentary sources were damaged by restoration procedures in the early- and mid-1900s. Restoration always carries some risk and sometimes a certain level of loss often has to be accepted in favour of the retention of the majority of material for a longer time. Conservation processes are now considerably less interventionist than they were, and focus on stabilisation rather than absolute repair.
DIAMM aims to ensure that nothing in the digital capture process will hasten the gradual natural deterioration of any source. In the long term it is hoped that the availability of high-quality and high-resolution colour images will allow archives to minimize the direct handling of each source as well as providing a stable reference point against which deterioration may be measured, and thus aid in conservation. DIAMM images have proved of sufficient quality to recover a great deal of material lost through the natural damage incurred during the life of the source, and in many cases have proved of greater benefit than examining the original source, since the ability to enlarge on screen well above normal size has enabled scholars to find material that is not visible to the naked eye.
Several manuscripts of medieval and early modern music are now withdrawn from public access, but the images are freely available here.
DIAMM does not use natural daylight nor flash because of the high UV content of these light sources. We also do not use a flatbed scanner, as the proximity, heat and brightness of scanning lights is potentially damaging. Instead we rely on cold fluorescent daylight-balanced tubes, which cast a clear cold light that emulates daylight in colour, but without the damaging UV content. These lights are mounted about 70-180 cm from the source and the image is captured using specialist digital imaging equipment (see Image Capture for equipment details). With a scanning back exposure times are quite long, but nevertheless significantly less than a split-second flash exposure, or a slow exposure under real daylight. Most imaging is done though with a high-resolution single-shot camera, where an image takes only a portion of a second. The intensity of the light is far less than with most flatbed scanners, even taking slow exposure times into account.
Although it is possible to place some loose leaves on a flatbed scanner, it is generally impossible with bound manuscripts, and highly undesirable from the conservation point of view. This method of capture is considered inadvisable even for loose leaves since, apart from the potential for damage from scanning lights, inks and particles of the surface or other material may stick on contact with the glass surface. For this reason DIAMM also does not place any items under glass to flatten them during photography.
The DIAMM team has now accrued considerable experience in handling a wide variety of sources in various stages of repair. We use specially-devised handling aids to hold pages flat with the minimum of physical contact. In general the book is allowed to find its own level and ‘comfortable' position, and the photographic procedure is adjusted to compensate, rather than forcing the book into an unnatural position for the convenience of the photographer. Occasionally this has meant that it was impossible to photograph details e.g. in binding gutters, but we felt that the loss of minimal material in this way was necessitated by the need for respect of the binding as a historical artefact in its own right.