Flat out access: unfolding the parchment pardon of Samuel Henry Horne

The conservators at the Western Sydney Records Centre treat items from across Museums of History NSW collections. A recent example is the 1832 absolute pardon of convict Samuel Henry Horne (spelled Horn on the pardon), donated to the Justice & Police Museum and previously featured in Convict turned constable. The pardon, written on parchment, was sent to the conservation laboratory for treatment to enable better access and digitisation.

The pardon had been stored folded for some time. Parchment is an untanned animal skin and has a strong physical memory. The parchment’s stiff folds were difficult to unfold, hindering access to the historical text found on both sides. Our aim was to relax these folds so that we could ultimately flatten the pardon to enable better access and viewing, and to allow us to take an improved digital image of this significant document.

Conservators flatten parchment using controlled moisture treatment methods to prevent damage from excess moisture. Water can change the structure of the collagen in the parchment, which then undergoes a process known as gelatinisation, where the collagen converts to gelatin, shrinks and hardens. This makes the parchment brittle and prone to breaking.

The humidification and flattening treatment usually follows three steps:

• Cleaning the parchment to remove any surface dirt.
• Controlled humidification.
• Flattening under tension and/or weight.

Conservator Jacinta Sanders started by cleaning the surface of the parchment using a cosmetic sponge. The soft sponge picked up some of the grime and dirt left on the parchment over the years.

Jacinta then prepared a Sympatex® chamber for humidification of the parchment. Sympatex® is a plastic membrane laminate that water can pass through as a vapor. It creates a gentle and controlled method of humidification. 

To create the humidity chamber, Jacinta prepared a ‘sandwich’ with these layers:

Mylar (top)
Parchment (object)
Sympatex®
Wet blotter
Mylar (bottom)

The humidity in the sandwich rose to 93 per cent within one hour. After three hours in the chamber, the parchment was relaxed and pliable enough for flattening. Some parchment documents may require drying with tension (using clips) if they are resistant to flattening. Fortunately, the folds in our parchment relaxed evenly, and the pardon was then placed between layers of felt and blotters to dry under weight.

After one week under weight, the pardon had dried and flattened well. The document can now be easily read on both sides and digitised for greater access.