Collaboration in practice: Clay poultices and regenerated cellulose membranes

Published on: Author: sarahfoskett Leave a comment

by Catherine Harris, 2nd year student, MPhil Textile Conservation.

My virtual placement experience, like all my classmates, was unexpected and came with challenges as well as tremendous rewards.

The research project, which made up my virtual placement, was with Zenzie Tinker Conservation Ltd (ZTC), an independent conservation studio based in Brighton, United Kingdom. Started by Zenzie Tinker in 2003, they are now the largest independent conservation studio in the UK, offering a wide range of conservation services, presentation and display.

Based on earlier tests done by ZTC, the project was to produce a testable method of using clay poultices and regenerated cellulose membranes (CP&RCM) to clean delicate historic textiles which are subject to dye bleed. The aim of my project was to develop the technique further in collaboration with Rachel Rhodes, a freelance textile conservator for ZTC.

There is no known record of the method being used in the UK and had been introduced to ZTC by a French textile conservator who was completing a summer internship with them. Being an unknown technique made it an exciting challenge and a test of what a had learnt from my first year on the programme.

As I was just finishing the first year on the programme, I had no experience of the use of poultices in textile conservation or conservation more broadly. Subsequently, the first task was to understand the method of a poultice – how it worked, what materials are used as a poultice and why and, crucially for textile conservation, why might it be useful as a treatment. This was a real challenge and I did get quite lost in the literature available, especially trying to understand the science behind the method.


Fig 1. Schematic of the set-up of a poulticing treatment.

For the purpose of this research project, the focus was on specific materials used and developed in France by Thalia Bouzid during her Master’s thesis.[1] Thalia developed the clay poultice method using montmorillonite clay, deionised water as the solvent and regenerated cellulose membrane as the barrier layer to treat very fragile archaeological textiles.

The materials were chosen for their properties:

Montmorillonite clay – highly absorbent, high charge (is it used in industry to remove impurities, particularly oil and dye residue) and it has buffering capacity.

Regenerated cellulose membrane – chosen for its permeability; slow release of moisture and it has smaller pore sizes than the size of the clay particles so there is no risk of the clay particles migrating through the membrane to the textile.


Fig 2. Poultice comprised on montmorillonite clay and regenerated cellulose membranes being tested for the removal of soiling from a sampler.

The practical tests were critical in my understanding of the method and how it could be used effectively. The collaboration with Rachel was an important support throughout the process and demonstrated the importance of collaborative work in textile conservation.

As we concluded the project and were able to write up a testable method that we hope to undertake later in the year, in person or virtually, I realised how far my knowledge of the technique had come and how much both me and Rachel had learnt about the technique and how it can be used effectively as a textile conservation treatment.

In the new virtual world we found ourselves in, the placement brought a new way of conducting research. Although the conditions were not ideal – the clay poultices were mixed in my breakfast bowl and were stored in my fridge alongside my groceries; the sampler was laid out on my dining room table and my husband was under strict instructions not to touch or move it – I found that there were many advantages to this way of working.

  • The textile conservators we contacted were based all over the world and were able to contribute and help direct our research. Can more collaborative work be done internationally?
  • For example, do we need to physically work together in a studio to be a team? Can we have a virtual studio to conduct research?

There is still further research and development in using clay poultices and regenerated cellulose membranes (CP&RCM) to clean delicate historic textiles which are subject to dye bleed, but I hope we have brought some valuable research that can be built on in the future.


[1] Bouzid, Thalia. “To conserve or to remove ancients interventions: study of seven Islamic mediaeval textiles restored or mounted at the end of the 19th or at the beginning of the 20th century.” Final thesis, Diplôme de Restaurateur du Patrimoine – Spécialité Arts textiles, Institute National du Patrimoine, 2002.

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