Notes on the Conservation of a Very Fragile Letter

on Tuesday, 27 August 2019. Posted in Archives, Conservation

A new project recently appeared in the archive conservation lab: a brittle and damaged looking document that turned out to be an interesting new accession.

Letter Sent to Francis Yerbury, 14th May 1747 (1387/1697)

The document is a letter sent to local Clothier Francis Yerbury in 1747. It is thought that he may have run a cloth mill in Trowbridge although the letter is about a mill in Bradford-On-Avon. Hanne Dahl, Exhibitions and Collections Officer at Trowbridge Museum has transcribed the letter and below gives an overview of the its content:

The letter seems to consist of two messages. One is regarding a cloth order which John Howell has received and is ensuring Francis Yerbury he will pay for. The other is a new cloth order for the Empress of Russia of Clergy cloth in scarlets and greens. 5 cloth samples of Yerbury’s are attached to the letter as a colour reference.
The Empress mentioned was probably Elizabeth of Russia who lived 1741-1762. According to popular history clothing was the chosen means in Elizabeth’s Court by which to display wealth and social standing and according to historian Mikhail Shcherbatov (1733-1790) her court was “arrayed in cloth of gold, her nobles satisfied with only the most luxurious garments, the most expensive foods, the rarest drinks, that largest number of servants and they applied this standard of lavishness to their dress as well.’ Hanne Dahl, Exhibitions and Collection Officer, Trowbridge Museum April 2019

The new accession was passed on to the archives here at WSHC by Hanne after being in the care of the Ponting family; the late Ken Ponting being former Managing Director of Samuel Salter Ltd. weaving mill in Trowbridge.

As is often the case with the documents I work on, there is much of historical interest and I could spend many hours researching them. However, as a conservator, once I have enough detail to inform my conservation decisions, I must tear myself away from the fascinating historical insight and prioritise stabilising and preserving the letter so that future researchers can access it safely.

The letter

It was originally folded to be posted and has the postal address visible on one of the folded sections. The letter is written in brown ink and has textile samples and a small part of a wax seal attached.

Several factors made this a conservation challenge; not only was the paper extremely thin and fragile but the additional attached textiles samples and seal remains also had to be considered at all times as they could easily become detached and lost.

The document needed to be packaged so that it could be safely stored in the archive but also handled without the risk of further damage. As the paper was so thin, it could easily tear again with further handling, even after conservation.

I decided that once repaired, the document would be safest inside a mount- this would allow for compensation of the thickness of the attached textile samples and seal remnants as the depth of the window mount would prevent them getting squashed or dislodged in storage. It would also enable easy viewing as and when required without direct handling of the letter. Text found on the back of the letter was all in one area so the mount could be adapted to have a viewing window on the reverse. This would also mean the document didn’t need to be taken out of the mount or handled to see this.

    
Areas of damage on the letter

Backing removal

The letter arrived with us inside a frame, attached to a backing board with tape partially holding it around some edges. The paper was so thin and weak that tears had started to appear along many of the original fold lines whilst large areas were breaking around the edges.
It was important to remove the letter from the backing for several reasons; the backing board itself, made from poor quality board was likely to be causing damage to the paper. Unless they are archival quality, backing boards and framing materials are often made of very poor quality materials with high levels of acidity. As these materials break down they can transfer acidity to materials they are attached to, increasing their deterioration. I also needed to access the document to effectively repair the tears and remove the adhesive tape.

I was able to successfully remove the letter from the mount using a spatula to ease the tape away from the board surface.

Using a spatula to detach the tape off the backing board

When the board was removed it was possible to clearly see acid transfer which appeared to be coming from the document and transferring onto the backing board, suggesting the paper itself is acidic. This is likely to be due to the ingredients used when the paper was originally made, for example additives such as sizing and fillers or the materials the paper is made from such as wood pulp. The ingredients vary between paper mills and throughout the history of papermaking, for example Lignin from wood pulp is extremely acidic and is generally found in modern papers such as newsprint. This is what makes newsprint go yellow and brittle so quickly.

The darker area of brown mirrors the document suggesting acid transfer from the paper onto the backing board

After removing the document from the backing a new area of writing was discovered where the letter had in fact continued overleaf. The archivist was then able to add this to the existing transcription.

A small area of text was found on the back of the letter after it was removed from the backing board

Once the letter was separated from the backing board I could then remove the adhesive tape. This task of removing tape is always daunting for a conservator as different adhesives react completely differently to different types of removal. Sometimes it can take a long time to find a method that softens or releases the adhesive so that the tape can be removed.

On this occasion I found that applying moisture directly onto the tape was enough to release the adhesive. However, a thick piece of brown adhesive tape down the left side of the letter was so stubborn that after removing a small amount I decided it would be better to leave that particular piece of tape on rather than risking damage to the already fragile paper surface.

Once the tape had been removed I surface cleaned the document being careful to avoid any weak areas. I was then able to move on to repairing and stabilising.

Repairs

Tears on paper documents are generally repaired by adhering small pieces of Japanese tissue to the reverse.

The tissue I used for the letter is only 5 gsm, so it is extremely thin and light- but strong enough to stabilise the tears and weak areas without distracting from the letter itself.

Infills

Two areas of the document had large gaps that although supported on the back with the Japanese tissue repairs, needed to be infilled with a paper of a similar thickness to the letter itself, to prepare the document for mounting. In the conservation of archival documents (as opposed to artworks) it is particularly important that repairs such as this are visible additions, clearly seen as modern repairs and not blended to make them invisible. This ensures that future historians and researchers are aware of the difference between the original document and any conservation work that has been done.

Creating an Inlay

The edge of the letter is traced onto the inlay paper
The inlay paper surrounding the letter shown on the lightbox to highlight the small gap around the edge

In paper conservation an inlay is a piece of paper that is attached around the outside of the document to protect it and prevent further damage to fragile edges. This is achieved by tracing around the edge of the document using a needle and then removing the inner piece of inlay paper to create a paper frame. The inlay paper is attached to the document by thin strips of Japanese tissue adhered along the gap between the two. The inlay protects the original document whilst still retaining full visual access to it. It also means that the document can be attached inside the mount by putting hinges on the inlay paper rather than directly on the document itself and that the letter can be fully displayed in the aperture of the window mount without falling out through the middle.

Overthrow mount with Perspex window in verso

This particular mount has been designed with three layers: the backboard complete with a clear polyester window to view the writing on the back of the letter; the aperture to frame the document and the overthrow lid to cover and protect the letter when not being viewed (it can be folded back on itself when the letter is in use). Once these are cut and put together the document is attached inside against the backboard by attaching Japanese Tissue hinges between the board and the inlay around the document.

Because the letter was transferring acidity onto the previous backing board I decided to use a special board in the mount which is designed to neutralise acidity with an alkaline buffer of calcium carbonate, also known as a ‘molecular trap’. This should help to reduce the acidity of the document and help to maintain its stability into the future.

Last but not least the mount is packaged in a simple archival folder to protect it whilst in storage.


This was a great project to work on and having even a snippet of the historical details of what you are working on is always really interesting. I’m very lucky to have access to some extremely knowledgeable Archivists in the office next door so I can get further details and feel a real sense of purpose for the conservation work I am doing.

Special thanks to Hanne Dahl from Trowbridge Museum https://www.trowbridgemuseum.co.uk/
for her help researching into the historical background of the letter.

The Conservation and Museums Advisory Service (CMAS) aims to promote excellence in the care and use of collections by providing conservation advice and practical treatments to heritage organisations and the public. It also supports museums in Wiltshire to meet professional standards and become sustainable.

If you would like conservation advice about your own documents or objects, we hold a free ‘Conservation Surgery’ on the 2nd Thursday of every month (please book in advance through the WHSC helpdesk – 01249 705500)

We are also holding the following workshops:

How to Care for Old Books
2pm Wednesday 25th September
Old volumes can be easily damaged if not looked after. Archive conservator Sophie will be demonstrating how to keep your bindings beautiful; with advice on what potential problems to look out for, basic cleaning and how to protect and store them safely.
£4, booking advisable.

How to Look After Your Wedding Dress (or any special outfit)
2pm Wednesday 23rd October
Have you often wondered if your cherished outfit will survive for future generations? Join us in our conservation lab where Object Conservator Kayleigh will demonstrate using a vintage Kimono to show the best way to package and store special garments.
£4, booking advisable.

How to Care for Your Jewellery
2pm Wednesday 20th November
Object Conservator Kayleigh will be demonstrating how to clean and protect silver jewellery and other precious valuables to keep your gems sparkling.
£4, booking advisable.

All events are held at WSHC unless otherwise stated. Tickets for events at the History Centre may be purchased in advance at the Help Desk or can be reserved on 01249 705500 (Tues-Sat 9:30-5) Numbers may be limited so please buy your ticket in advance. Please aim to arrive 15 minutes before your event begins.

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