UA research just might stick for the field of art restoration

The University of Akron’s polymer scientists and engineers usually do their best research in a lab. For one of their recent projects, however, UA’s researchers found themselves in art galleries, museums, and even the rooftop of a building in New York City and a courtyard in the city of Turin, Italy.  
 
The result of that research – most of which was in fact accomplished inside UA’s Goodyear Polymer Center – is an innovation that should prove to be transformative for the field of art restoration. 
 
Dr. Ali Dhinojwala, the W. Gerald Austen Endowed Chair and H.A. Morton Professor of Polymer Science, and a team of undergraduate, graduate and post-doctoral students have in the past two years developed a formulation for an adhesive to be used for the safe relining of linen canvases, therefore potentially saving priceless artwork around the world. 
 
The Akron formulation, as it is likely to be known, could replace the current formulation, which requires what many art restorers believe is too high of a temperature during the application process. Too much heat can damage delicate materials used hundreds of years ago.  
 
This huge advance in art restoration technology was funded by the Getty Foundation’s Conserving Canvas project, an international grant initiative focused on the conservation of paintings on canvas. The initiative ensures that conservators remain prepared to care for paintings on canvas supports through training, information dissemination, and scientific research. Eventually, UA’s formulation will be published to ensure easy and affordable access to the product in perpetuity, which is a stipulation of Getty’s support. 
 
UA is collaborating closely with the Conservation Center at the Institute of Fine Arts at NYU, which is leading the project from the art restoration side. Other collaborators include the Cleveland Art Museum, the Metropolitan Museum of Art and the Museum of Modern Art, both in New York City, and the National Gallery of Art in Washington, D.C., and a number of museums in Europe. 
 
So far, several hundred art restorers have participated in both in-person workshops and online presentations about the findings, which is an indication of the significance of this research to the relatively tiny field of restoration. 
 
Restorers who use adhesive to re-line canvases have been waiting for this advance in the technology. 
 
The process of relining a painting is complicated but necessary if a painting has been damaged in handling or transportation, or if environmental factors have caused the materials to degrade over time. In the process of relining, a restorer might remove the old lining from the back of the painting and adhere a new lining. Alternatively, a restorer could adhere a new lining on top of the old one. In either case, the adhesive is the key to effective relining. 
 
For many years, the industry-standard adhesive for art restoration of this kind was called BEVA 371, which is an abbreviation for Berger-ethylene vinyl acetate The name Berger refers to Gustav Berger, a noted art restorer who developed the formulation in the late 1960s. By the 1970s, BEVA 371 was among the most widely used adhesives among art restorers.  
 
To use an adhesive formulation such as BEVA 371 for applying a new liner to a canvas, restorers mix the formulation in a solvent and then apply it to the back layer of the painting. The adhesive is then heated to a particular temperature to ensure it becomes tacky and the materials stick to the artwork. As soon as the adhesive tacks, the new lining can be applied. 
 
BEVA 371 becomes tacky between 50 and 55 degrees Celsius, and restorers were satisfied for years that the artwork was safe from that level of heat. 
 
But around 2008, the company that manufactured BEVA 371 ended production. Art restoration is a low-demand enterprise, and the demand may not have been high enough for the company to continue producing the formulation, Dhinojwala believes. 
 
A new formulation, BEVA 371b, has since come on the market. The preparation is the same, but the temperature necessary for tackiness is around 65 degrees Celsius. Restorers have been using it but have long been uncomfortable with the higher temperatures needed to develop the tack. The Getty Foundation held a Conserving Canvas workshop in 2019, during which the foundation heard about issues with the replacement formulation, and that’s when the Getty support started. UA was brought on because of its reputation in the area of developing polymers for adhesives. Dhinojwala’s current research is in adhesion, wetting and friction. 
 
The UA team, led by Dhinojwala, has included undergraduate and graduate students and postdoctoral researchers. The team developed a formulation that they have observed becomes tacky at around 58 degrees Celsius. Not as cool as the original BEVA 371, but an improvement over the replacement formulation. 
 
The researchers started their work by examining the different rosin ester-based tackifier agents available on the market. They narrowed the search down to four agents, known in the UA lab as A, B, C and D. The team developed a formulation for each tackifier agent. 
 
Testing in the lab showed promising results for all four formulations. The UA researchers then scaled up the formulations to perform more tests and made them solid so that samples could be sent to their counterparts at NYU, where the art restoration team there added the solvent to create the adhesive. They tested the formulations in New York and found that the adhesive properties and temperatures were promising in three of the four formulations.  
 
“The results were comparable to the original formula, so that helped us understand that the tackifiers we short-listed were working well,” said Dharamdeep Jain ’17, a postdoctoral researcher in Dhinojwala’s lab. 
 
The next step for UA was to make quart-size batches of the adhesive to send to project partners working on restoration in museums and galleries in the U.S. The UA researchers were particularly interested in how the four formulations would respond to different conditions, techniques and materials used by restorers. For example, some restorers use heated tables to warm the adhesive and create tackiness, while others use heat guns. 
 
The partners tested three formulations and sent back samples of the results. They also sent feedback, which the UA team aggregated into a chart. Formulations B and C emerged as the most promising.  
 
Not only were the formulations becoming tacky at a lower temperature, but they were effective on a variety of materials, particularly linens and animal-based adhesives used in the canvases. This is significant because hundreds of years ago, artists did not have access to a common source of uniformly produced supplies as a modern artist might have in an art supply store or an online source. Each artist made or purchased supplies from a local producer, so linens and adhesives varied wildly. The fact that the UA formulations were effective in tests of many different materials is promising. 
 
“It has to work perfectly for them,” Dhinojwala said. “Otherwise they’re not going to use it.” 
 
The next step was to allow restorers to learn about and test the formulations in two hands-on workshops. The first was held from May 30 to June 2 at NYU’s Institute of Fine Arts, located just a few blocks away from the Metropolitan Museum of Art. Participants came from as far as Canada and Mexico. The second workshop was held July 4-7 in the Italian city of Turin at Centro Conservazione e Restauro La Venaria Reale. Attendees came from all over Europe, including the United Kingdom, Ukraine, the Netherlands and other areas of Italy. 
 
Workshop attendees, who were mostly young restorers from different museums, had an opportunity to try out the formulations, which had to be done on the NYU building’s rooftop and in the Centro’s courtyard because of the number of people observing and the potential for fumes. Again, formulations B and C were the two most promising. 
 
Dhinojwala and Jain, who attended both workshops, returned to the UA campus with a decision to make—which formulation to present in the research to be submitted for publication this fall.  
 
Additional research has led Dhinojwala and his team to develop formulations that do not require a solvent to be used, which eliminates the complication of creating harmful fumes during preparation in spaces without proper ventilation. That is what led the research group outdoors during workshops in New York City and Italy that were held in spring and summer 2023. The UA researchers have experimented with the adhesive in the form of a strip of film and also in solid pellets, the latter of which was shipped internationally for testing. The other benefit of these alternative forms of the adhesive that as a solid, they can be mixed into the solvent as needed rather than having a pre-mixed formulation sitting on a shelf for months and potentially losing effectiveness. 
 
Regardless of the outcome, the research experience has been a unique one for Dhinojwala, who has been at UA since 1997. It’s not just UA and NYU researchers who have participated – others from museums in Rome and museums in the U.S. have been enlisted as painting conservation experts. Another group of partners are offering support as a network of scientists and engineers, including UA’s Abraham Joy, a professor of polymer science and polymer engineering. Other experts represent the University of Amsterdam, Virginia Tech, Buffalo State, the University of Verona and CTS Italy, and the Delft Technical University and CTS Italy, a company that manufactures linear guides for moving items. These experts periodically review the research produced in the lab and the findings determined in the field. 
 
A total of 23 individuals have contributed to the project, including a project-high six from UA. 
 
“It’s an interesting approach of working on research that I had not done before,” Dhinojawala said. “Collaboration can be uncommon in science. If you think about it, when we do our research it’s an idea, a single person or maybe a few people working on it. With this project, all of these people from all over the world have been involved since day one. They have been part of the development along the way.”