In September 2016, the city of Edinburgh hosted the course “Water and Paper Conservation Principles”, organised by The Scottish Conservation Studio
(www.scottishconservationstudio.co.uk) in association with ICON Scotland Group. Due to the number of participants, the course ran twice, one session on 6/7th September (kindly hosted by The Scottish Conservation Studio), and the other one on 8/9th September (hosted by the National Library of Scotland). The tutors were paper conservators Doris Müller-Hess (private conservator from the Institute for Paper Conservation Schloß Schönbrunn studio in Vienna) and Hildegard Homburger (private paper conservator from Berlin).
The aim of the course was to study and discuss the principles behind the interaction of cellulose and water, and the resulting behaviour of paper-based materials in contact with water during degradation mechanisms and conservation procedures. Various references were discussed, but the most important source was the fundamental publication “Paper and Water: a Guide for Conservators” (Banik and Brükle, Routledge 2011).
Each day the topics were firstly analysed theoretically, then some of the conservation techniques were demonstrated by the tutors.
I took part in the 8/9th September session at the National Library of Scotland, in a group of 16 conservators both from institutional and private conservation studios.
On the first day, after a short introduction, a very intense theoretical session explored the chemical and physical properties of water, cellulose, and the interaction mechanisms between the two elements at a chemical level and, specifically, during conservation treatments of paper such as humidification and washing.
We then received a demonstration of humidification systems (in particular, using a damp pack with GoreTex® or SympaTex®) and washing methods (washing with blotting paper, float-washing with a silk screen, and capillary washing with Paraprint OL60). The group discussed their personal experiences of using SympaTex® and GoreTex®, and many agreed that they found GoreTex® was most suitable for slow and controlled humidification of very reactive paper-based artefacts.
Hildegard Homburger talked about an impressive four year-long project undertaken by the Federal Cultural Foundation and Akademie der Künste for the conservation of the Hans Scharoun archive, described in the publication “Paper – Line – Light. The Preservation of Architectural Drawings and Photoreproductions from the Hans Scharoun Archive” (Barkhofen, Brueckle, Glueck, Grzimek, Homburger, Hummert, Konarzewski, Kuehner, Lohrengel, Morgenstern, Penz, Simmons, Akademie der Künste, 2012). One part of this project involved the treatment of thousands of rolled architectural drawings on tracing paper that needed to be flattened before storing. An effective and relatively fast one-side damp pack and felt-layered drying process was developed. The best results were obtained with the use of a GoreTex® membrane. Concerning the washing methods, the one that involves the use of Paraprint OL60 was, in my opinion, the most interesting and a new discovery for most of the participants. Discussed in-depth in the publication “Aqueous Treatment of Water-Sensitive Paper Objects” (Schalkx, Iedema, Reissland, van Velzen in Journal of Paper Conservation Vol. 12 -2011, No. 1, pp.11-20), this method takes advantage of the orientation of the extremely absorbent vertical acrylate-bonded viscose fibres that form the Paraprint OL60 sheet, and the capillary force that transports water from one side of the sheet to the other with a certain orientation. A tray of water was placed on a raised surface, and a rigid support with a sheet of wet Paraprint OL60 laid onto it, with a portion directly immersed in the water. Another empty tray was positioned on the opposite side of the rigid support, lower down. The method works using gravitational force. The artefact that needed to be washed (in our case, a small print with gouache painting) was gently humidified, then placed directly onto the wet Paraprint OL60 sheet; after a while we could clearly see the brown degradation products from the paper (removed thanks to the action of water) slowly moving from the print along the Paraprint, transported by capillary force along the vertically oriented fibres. Fifteen to twenty minutes later, the water with the degradation products from the print reached the empty tray; the process continued until no more yellow product was visible. I did not notice any alteration/discolouration of the gouache colours. This capillary washing method may be really useful for treating artefacts with water-sensitive media. As the water removed the degradation products from the paper, moving not through but under the artwork, this mechanism avoids the possible risk of deposits of unwanted acidic elements being carried from one point of the artefact to another during washing.
On the second day, the tutors explained the importance of the quality of the water used in conservation treatments (presence of unwanted ions, and products residual from the industrial “refining” methods), and the advantages/disadvantages of the different kinds of water purification (filtration, activated carbon filtration, distillation, demineralisation, reverse osmosis). Moreover, a theoretical and practical analysis of the process of paper drying was offered. We studied the chemical and physical behaviour of paper fibres when water is added and removed, the reasons under the most common problems that conservators encounter (rolled works, creases, distortions, cockling), and the pros and cons of different methods of drying paper.
A very important concept outlined by Hildegard Homburger and Doris Müller-Hess was the difference between actual and potential shrinkage of paper fibres during humidification and drying, and why conservators should pay attention to that during treatments and how we can take advantage from it in certain cases.
The afternoon of the second day was dedicated to practical demonstrations of some of the drying techniques studied. The National Library of Scotland conservation studio kindly made available a Karibari screen for a demonstration of drying techniques in which no pressure but tension is involved.
I found particularly interesting the “hard-soft sandwich” pack, and the so-called “friction drying” technique.
At the end of the demonstrations, every one of us had the opportunity to ask questions and talk about personal experiences in a very friendly and stimulating environment. We also received samples of some of the materials mentioned during the course, generously provided by the German company GMW.
The course offered me the opportunity to review what I learned during my Degrees in Italy some years ago, and think about these fundamental topics from perspectives that I had not fully considered before. I particularly appreciated that, after a very clear and focused theoretical approach, our tutors and all the participants shared their extensive knowledge and experience, talking about practical cases and giving very useful tips and thoughts.
In conclusion, my experience with this course was absolutely positive, and I really encourage paper conservators to keep an eye on what happens in Europe and attend this workshop, or to contact the tutors to organise a session in their city!
About the Author
Laura Dellapiana has an MA in Conservation and Restoration from the Academy of Fine Arts of Turin, Italy. She is specialised in conservation of books and paper-based materials and worked on European and Asian artefacts. In 2013 she completed a four-month internship at the Laboratorio di Restauro Polimaterico at the Vatican Museums, Vatican City, for her MA Thesis. In 2015, she was a Postgraduate Fellow in Conservation of Museum Collections at the Smithsonian Institution Archives in Washington, DC, studying a new method for the stabilisation of modified iron gall inks in letterpress copybooks.