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Thursday, May 16 • 9:30am - 10:00am
(Wooden Artifacts) Strengthen Methylcellulose with Nanocellulose for High Relative Humidity

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In this paper we discuss the strengthening of methylcellulose (MC) with nanocrystalline cellulose (NCC) and with microfibrillated cellulose (MFC) for high relative humidity (RH). MC is the least hydrophilic cellulose ether among the water soluble ones. Its long-term stability is very high. The same is true of its purity, according to Feller and White (1990). A good tensile strength for re-adhesion of flaking paint on canvas or wood as well as for wood glueing has been proven by many conservators. Therefore the use of MC is becoming more common in the field of conservation. However, the cohesion decreases dramatically when the relative humidity is rising (Debeaufort und Voilley 1997). In the range of 22% RH to 53% RH, the difference in tensile strength was only 9%, whereas for 75% RH the decrease amounted to 46%, for 84% RH even 80%. Nanocellulose has been recently proposed as a novel consolidant for canvas and paper consolidation as well as a reinforcement for some consolidants at room temperature and 50% RH. However, most of our heritage is located in churches, castles, collections or museums without climate control systems. Often the RH is 75%, 84% or even 100%. Therefore we started to strengthen the tested methylcellulose in order to maintain a product more resistant to high RH. After drying, pure NCC and MFC are no longer water-soluble. This is not in accordance with our professional requirements regarding retreatability or reversability. However, the adhesive mixtures MC-MFC/NCC stay water soluble when mixed with methylcellulose. Consequently, mixing the components MC and MFC or NCC could lead to a water soluble yet more resistant adhesive at high RH. Hence we tested the ratio of the components, the preparation, the homogenizing methods (magnetic stirrer, dissolver, SpeedMixer, hand-held blender and ultrasonic), the application, the drying and, finally, the behaviour at high humidities (75% RH, 84% RH and 100% RH). Several analytical techniques were used for the product characterization (tensile strength tests, elasticity tests, weighing technology) as well as scanning electron microscopy (SEM) and atomic force microscope (AFM). Subsequently we analyzed the penetration into porous chalkground on wood by means of fluorescent dyed cellulose and thin sections. The mix of MC and NCC showed the smallest loss of tensile strength during high RH. The tensile strength of the mixture at 75% RH corresponded with the tensile strength of pure methylcellulose at 50% RH. We developed a final product which is substantially more resistant to high humidity than pure methylcellulose and which shows that ratio, homogenizing and application methods are crucial.

Speakers
avatar for Karolina Soppa

Karolina Soppa

Prof., head of the painting and sculpture specialisation, Bern University of the Arts, Department of Conservation and Restoration
Karolina Soppa graduated from the Stuttgart State Academy of Art and Design (Germany) in 2006 with a diploma in Conservation and Restoration of Paintings and Painted Sculptures (thesis on the penetration of polybutylmethacrylates in canvas paintings). After working for half a year... Read More →

Co-Author
ES

Elisa S. Carl

MA-Student, Bern University of Applied Sciences
Elisa S. Carl is currently master student at the Bern University of Applied Sciences in the conservation and restoration of modern materials and media.
KK

Kevin Kohler

MA-Student, Bern University of Applied Sciences
Kevin Kohler is currently master student at the Bern University of Applied Sciences in the conservation and restoration of paintings and sculptures, specialising in the conservation and restoration of wooden sculptures.
TG

Thomas Geiger

Dr., Empa, Swiss Federal Laboratories for Materials Science and Technology
Thomas Geiger (born in 1969) works at Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland in the section Applied Wood Materials. He received his diploma degree in 1995 and completed his PhD study in 1998 at department of Chemistry, Pharmaceutics... Read More →


Thursday May 16, 2019 9:30am - 10:00am
Abenaki Room Sky Convention Center, Mohegan Sun
  • Track Wooden Artifacts
  • Ticketed Included in Main Registration
  • Authors in Publication Order Karolina Soppa, Kevin Kohler, Thomas Geiger, Elisa S. Carl
  • Abstract ID 18886
  • Tags methylcellulose,nanocellulose,NCC,MFC,high humidity,tensile strength

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