Conservation of a Tudor warship: Investigating the timbers of the Mary Rose By Eleonora Piva The thesis is submitted in partial fulfilment of the requirements for the award of the degree of Doctor of Philosophy of the University of Portsmouth Portsmouth University Mary Rose Trust September 2017 DECLARATION Whilst registered as a candidate for the above degree, I have not been registered for any other research award. The results and conclusions embodied in this thesis are the work of the named candidate and have not been submitted for any other academic award. Word count: 36229 1 ACKNOWLEDGEMENTS First of all I would like to thank my supervisors: Eleanor Schofield who has been with me all the way, supporting me and encouraging me and from whom I learnt so much; and David Begg and Nikos Nanos, who have always believed in me. I would like to give an enormous thank you to Dominique Derome for introducing me to the wonders of Neutron imaging, and to the wonderful people I met at EMPA, in particular the Guylaine and Stephan: I couldn’t have hoped for better people to help me and literally spend day and night working with me at PSI. Speaking of, a big thank you to David Mannes and Jan Hovind who have been able to solve all (or almost) our problems. I also would like to thank the staff at the Mary Rose who made my work possible: Simon H., Jack, Alex G., David, and Jo I will truly miss our excursions on the ship hull, and also Brian, Tony, Eric and Simon you made all this work possible and my time at the Museum something to always looking forward to. A special thank you goes to Mark Jones, who taught me what I know about Maritime Conservation and who actually convinced me to pursue this PhD. My experience would not have been a pleasant time without the magnificent ICG crew who adopted me since day one of PhD induction. Mat, Hedda, and Ben I am truly so happy we have been in this sort of together. To my family, my mum, dad and sister, I don’t even know how I should start. Thank you for allowing me to be here, for supporting me even if far away, for always having my back, and for being so wise, all of you, so much more than me. And finally Liam, whom I love and to whom I really owe so much I don’t know how to express either concepts. Thank you. 2 ABSTRACT The Mary Rose is the only Tudor warship in existence, and as such is an important archaeological artefact. Since she was raised in 1982, and since then has undergone conservation treatment to preserve her structure while on display in the Mary Rose Museum. Displaying an artefact which has been waterlogged for 500 years, in this kind of environment, presents a number of unique challenges relating to the structure and chemistry of degraded archaeological wood. This thesis outlines several approaches to monitoring the state of the Mary Rose, and consequently the progress of her conservation treatment. This monitoring relates to both her macroscopic structural state, as well smaller scale structure, and the distribution of moisture throughout her hull. An overview of the Mary Rose and her history, of wood characteristics, degradation causes in waterlogged environments and archaeological wood behaviour, of conservation techniques, their application to comparable artefacts and of investigative techniques used with cultural heritage is first given. The methods and materials used in this thesis are then described. The Mary Rose is monitored for her MC% with core samples. The structural survey is carried out with a Total Station and a new manual method involving laser pointers for the understanding of global movements taking place on the hull. A manual survey focused on local movements is also described. Neutron imaging is used on Mary Rose wood samples to better understand the behaviour of PEG treated archaeological wood when drying. Neutron radiographies of the samples are taken during drying simulations of the conditions on the Mary Rose hull. The monitoring shows that the hull of the Mary Rose has reached MC% below 15% throughout the depth of the timbers. The structural survey shows movement taking place in the entire hull: the Decks of the ship are shifting in opposite directions, the Starboard side is folding into the Port side and the structure is moving downwards. It is also possible to relate the cracks on the ship’s timbers to the fast initial loss of free water and the loss of bound water from the timbers when the ship started drying in 3 2013, but structural movements are likely connected to the lack of structural integrity. Neutron imaging underlined the peculiar drying behaviour of PEG treated wood, showing a uniform drying front rather than preferential paths following the wood structure. The method also confirmed the ability of PEG in reducing wood shrinkage upon drying. Future work is suggested, both in terms of the ship monitoring and with regards to the further analysis of drying behaviour of treated archaeological wood. 4 CONTENTS Declaration ................................................................................................................... 1 Acknowledgements ...................................................................................................... 2 Abstract ........................................................................................................................ 3 List of Figures ............................................................................................................... 8 List of Tables ............................................................................................................... 12 Abbreviations ............................................................................................................. 13 Dissemination ............................................................................................................. 14 1 Introduction ....................................................................................................... 15 1.1 Introduction ................................................................................................. 16 1.2 Ethics in Conservation ................................................................................. 17 1.3 the Mary Rose ............................................................................................. 18 1.3.1 History .................................................................................................. 18 1.3.2 Ship structure ....................................................................................... 25 1.4 Wood ........................................................................................................... 28 1.4.1 Wood structure .................................................................................... 28 1.4.2 Heterogeneity and anisotropic behaviour of wood ............................. 31 1.4.3 The relationship between wood and water ......................................... 32 1.4.4 Archaeological wood from waterlogged environment ........................ 34 1.4.5 The Wood of the Mary Rose ................................................................ 38 1.5 Conservation ................................................................................................ 40 1.5.1 Conservation of waterlogged wooden artefacts ................................. 40 1.5.2 PEG treatment ...................................................................................... 44 1.5.3 Conservation of the Mary Rose. .......................................................... 45 1.6 Investigating techniques ............................................................................. 47 1.6.1 Techniques for investigation of wood in cultural heritage .................. 48 5 1.6.2 Monitoring shipwrecks......................................................................... 50 1.7 Scope of the Project .................................................................................... 53 1.7.1 Importance and contribution of proposed research ........................... 53 1.7.2 Aims and objectives ............................................................................. 55 2 MATERIALS AND METHODS ............................................................................... 57 2.1 Moisture content monitoring ...................................................................... 58 2.1.1 Core extraction and moisture content determination ........................ 58 2.1.2 Selection of sample locations from the hull ........................................ 59 2.1.3 Analyses of the moisture content data ................................................ 63 2.2 Dynamic vapour sorption analysis .............................................................. 63 2.2.1 Principles of Dynamic Vapour Sorption ............................................... 63 2.2.2 Mary Rose samples for DVS testing ..................................................... 65 2.2.3 DVS experimental set up ...................................................................... 65 2.2.4 Vapour sorption isotherm analyses ..................................................... 65 2.3 Neutron imaging .......................................................................................... 65 2.3.1 Application of Neutron imaging to the Mary Rose .............................. 66 2.3.2 Instrumentation ................................................................................... 67 2.3.3 Samples selection and preparation ..................................................... 69 2.3.4 Drying run with concurrent