The Conservation and Museum Advisory Service (CMAS) has recently had some more archaeological finds in the lab. We work with several archaeological services who often bring corroded metal from recent digs as metals are more likely to survive a burial environment. So, we were excited to receive a large collection of waterlogged archaeological leather from Oakford Archaeology which posed a very different challenge. 

Figure 1 Waterlogged Leather prior to conservation treatment 

The collection consisted of 47 items ranging from an almost complete leather shoe to small unidentifiable fragments, and lots and lots of shoe soles. 

The first stage was to remove the soil and dirt from the surface of the leather to assist with identification and reassociation. This was carried out using running water and soft brushes, working over a mesh to ensure no fragments of leather are lost down the plug hole.  

Figure 2 Set-up for wet cleaning of the leather and the leather wrapped during pre-freeze treatment 

Grain pattern analysis was then carried out to try and identify the type of leather present. This involves studying the leather under magnification and comparing the hair follicle patterns on the surface of the leather with known examples. Identification was made challenging due to the poor condition of the surface of the leather fragments, but it is believed that the majority of the leather is bovine, which matches information found about the history of shoe manufacturing. Further analytical testing could be carried out to confirm this, but these techniques are destructive so would damage the items.  

Figure 3 Stitch patterns visible on some leather fragments after cleaning 

Through our research, we were able to identify some interesting stitch patterns on fragments and a potential heel strap from a Patten – a type of over-shoe designed to raise your feet higher than the wet and muddy ground. 

Figure 4 Leather fragment potentially identified as part of a patten with an extract from ‘Shoes and Pattens’ by Francis Grew and Margrethe de Neergaard 

Treatment to preserve waterlogged leather for the long-term involves a controlled drying process. The items were first submerged in a polymer solution which replaces the water molecules within the leather structure and helps support the material once dried. The items were then freeze-dried. This involves pre-freezing the items in a commercial freezer before placing them at even lower temperatures under a vacuum in a Freeze-dryer. The freeze-dryer causes the water molecules to sublime, going from ice to a vapour, without it going through a liquid phase. This dries the leather with minimal shrinkage and faster time than air-drying alone. 

The shoes could then be reconstructed and packed with support materials. 

Figure 5 Fragments of leather after treatment – reassociated and supported with mounts 

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. We also support museums in Wiltshire to meet professional standards and become sustainable, resilient organisations. 

If you have a conservation query, want a quotation to carry out some work, or would like to book a free appointment for one of our conservation surgeries, we would love to hear from you! You can contact the team by email cmas@wiltshire.gov.uk or why not follow us on social media: 

Facebook: CMASwilts 

Instagram: @heritagecmas 

Linkedin: Conservation and Museums Advisory Service 

Kayleigh Spring, Conservator