Previous conservation treatments: learning from the past

Twenty-one of the sheets have had previous conservation treatment, for which there is no documentation of when the work was carried out, by whom, or what was done. However, we can get a few clues from the condition of the sheets.

Previously treated sheet showing transparency.

Previously treated sheet showing transparency.

The sheets still have some degree of planar distortion but are generally much flatter. Gelatinisation in some areas has also worsened.

Less planar distortion.

Less planar distortion.

Complete gelatinisation in some areas.

Complete gelatinisation in some areas.

Each sheet has a layer of adhesive on the surface and a mesh like pattern imprinted into it.

Mesh pattern in surface of parchment.

Mesh pattern in surface of parchment.

A fairly standard method used in the past for drying parchment under tension, was to paste it out with an adhesive (most likely wheat starch paste) onto Terylene (or a similar fabric) and leave it to air dry. This is the method that seems to have been used here. It seems likely that having been pasted out onto the Terylene, the sheets were then also pressed with a board with some weight on top. This can be seen through the combination of the transparency of much of the parchment, the imprint of the Terylene weave into the surface, and in some cases some very deep, but very flat creases.

Pressed creases.

Pressed creases.

Compared to the untreated sheets this sheet shows more gelatinisation, which is probably caused by the treatment that was carried out. This previous intervention has led to further denaturing of the parchment with an increase in gelatinisation. The parchment is physically less stable now than it was before treatment.

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Damage ratings

These are some of the results we have collected:
Each sheet could be assigned a number depending on the extent of the creasing present; if there were creases but no text obscured it was C1, if there were creases which obscured one area of text it was C2, and if there were creases that obscured more than one area of text it was C3.

Only 13% of the sheets were rated as C1, so in no need of treatment. The other 87% of the sheets were designated as having at least one area of text obscured, so a C2 or C3 rating, and 74% of these were rated as C3. These crease ratings can be viewed alongside an overall damage rating for each sheet of 1, 2 or 3 (1 being slightly damaged, 2 being damaged and 3 being heavily damaged). All sheets were rated at either 2 or 3.

Damage rating 2 Damage rating 3
C2 21 (13%) 16 (10%)
C3 30 (18%) 78 (47%)

So, just under half of all the sheets are heavily damaged with more than one area of text being obscured by a crease. These sheets will be the most challenging to treat.

C2 rating 2

C2 rating 2

C2 rating 3

C2 rating 3

C3 rating 2

C3 rating 2

C3 rating 3

C3 rating 3