Examples of how we conserve different materials

PRONI holds a wide variety of documents which are from both public and private collections. Paper documents make up the largest percentage of our archives, along with parchment, seals, and photographic material (photographs, cellulose negatives, and glass plate negatives). We also hold numerous volumes and some artworks.

Our collections cannot last forever. They are made of natural materials which will break down over time. Often the deterioration of an object is caused by how it was manufactured or what it is made up of. Manufacturing ingredients such as chlorine bleach, aluminium sulphate (size), untreated wood pulp and water which contains metal particles can all contribute to the deterioration of our documents. Iron gall ink has been used as a script ink for centuries; it can actually burn its way through a page over time. Other inks, pigments, and adhesives can also harm our documents.

Parchment:

Removal of inappropriate repairs and applying new ones

Examination of the document revealed that old thick parchment repairs were putting pressure on the document and tearing it. Old acidic stickers were also causing chemical damage to the archive.

Removing old repairs Shiving parchment Applying more appropriate repairs

The document was humidified to aid in easy and secure removal of old inappropriate repairs and stickers. New parchment repairs slightly thinner than the document were prepared and applied to tears, loose elements and missing areas with gelatine adhesive made in the studio.

Pendant seal:

Repairing a broken seal & making up a suitable enclosure
Due to mishandling or poor storage the pendant seal had broken in 2 & there was a large missing area.

The proposed treatment was to repair the seal & make a suitable enclosure.

Damaged seal. Heating beeswax and infilling missing area and crack. Making a protective box

The pendant seal was attached to a parchment document. During the treatment of the seal special attention was made to protect the attached parchment document by wrapping it in a paper cover. The treatment of the seal involved piecing together the 2 pieces & sympathetically infilling the missing area. A suitable box, made from archival material was made to measure. The box has 2 compartments, one for the parchment document & another moulded compartment for the seal with a protective piece inside the lid to hold the seal in place.

Pendant seal and parchment in new box.

Photographs:

Removal of harmful boards and repairing tears

The photograph was damaged in a number of ways. It was faded and torn around the edges. There was also foxing (dark circular spots), possibly caused from the acidic board which was attached to the back of the photograph.

Examining the photograph Removing the harmful backing Repairing the tears Archivally mounted

Examination of the photograph under a microscope and a spot test helped us identify the photographic process as an albumen print. The harmful backing was then removed, the tears were repaired using a methyl cellulose paste (a very dry paste) and a silver safe (archival paper for photographs) was applied , and a new archival double mount board with a melinex (polyester) sheet couched in between was custom made in the studio to support the photograph while in storage.

Paper:

De-acidifying a document and repairing tears and missing areas
The paper is pH 5 (acidic) Ink test shows ink is stable Applying repairs Washing and de-acidifying

The document was torn, weak and had small missing areas all along the fold lines. A pH test also confirmed that the document was acidic. Acidity can be harmful to the make up of paper. Before washing and de-acidifying the document an ink test was carried out to make sure that inks would not run during treatment. The ink test showed that the inks were stable so the document was washed in de-ionised water and then de-acidified in a calcium hydroxide solution. It was then left to dry and Japanese paper repairs were applied to the tears, weak areas and missing areas with a wheat starch paste. The result was a pH neutral document whose weak areas had been stabilised. The document was not re-folded but instead was placed into a stress free environment in large archival envelope.