Tag Archives: Campo Santo di Pisa

Bacterial art lovers

With all the emphasis on eradicating bacteria (with signs everywhere telling you to wash your hands, often will illustrated instructions), it’s easy to forget that some bacteria are necessary for health. It also turns out that some bacteria can help us preserve art works. From the June 7, 2011 news item on Nanowerk,

Researchers at the Institute of Heritage Restoration (IRP) and the Centre for Advanced Food Microbiology (CAMA), both from the Polytechnic University of Valencia (Spain), are beginning to experiment with this new technique on the frescoes of Antonio Palomino from the 17th century in the Church of Santos Juanes in Valencia.

They have shown that a certain type of micro-organism is capable of cleaning works of art in a fast, specific and respectful way as well as being non-toxic for the restorer or the environment.

Here’s the background on the problem the art restorers were trying to fix (from the news item),

The project came about when the IRP [Institute of Heritage Restoration] was in the process of restoring the murals of the Church of Santos Juanes that were virtually destroyed after a fire in 1936 and were improperly restored in the 1960s. The researchers tested new techniques for filling with transferred printed digital images in spaces without painting, but had great difficulty dealing with salt efflorescence, the white scabs caused by the build up of crystallized salts and the enormous amount of gelatine glue remaining on the pulled-off murals.

With the problem defined, the researchers then investigated a technique developed in Italy that looked promising (from the news item),

Therefore, Rosa María Montes and Pilar Bosch travelled to Italy to learn from the authors about the pioneering studies that used bacteria to remove hardened glue that was very difficult to treat with conventional methods.

The restoration of the Campo Santo di Pisa wall paintings was performed under the direction of Gianluiggi Colalucci, restorer of the Sistine Chapel, and his colleagues Donatella Zari and Carlo Giantomassi who applied the technique developed by microbiologist Giancarlo Ranalli. The researcher had also been testing with black crusts that appear on sculptures and artistic monuments.

The team returned to Spain to practice the technique and add some refinements (from the news item),

Back in Valencia, the multidisciplinary team perfected this method and trained the most suitable strain of Pseudomonas bacteria to literally eat the saline efflorescence found in the lunettes of the vault behind which pigeons nest.

“By the action of gravity and evaporation, the salts of organic matter in decomposition migrate to the paintings and produce a white crust hiding the work of art and sometimes can also cause the loose of the painting layer” says Pilar Bosch.

These scientists have managed to reduce the application time, and have also innovated in the way of extending the bacteria. According to Dr. Bosch: “In Italy they use cotton wool to apply the micro-organisms. We, however, have developed a gel that acts on the surface, which prevents moisture from penetrating deep into the material and causing new problems.

“After an hour and a half, we remove the gel with the bacteria. The surface is then cleaned and dried.” Without a wet environment, the remaining bacteria die.

Here’s a picture that demonstrates the advantages of the new process according to whomever wrote up the caption in Spanish (I may have gotten the translation wrong),

Las ventajas del nuevo proceso (The advantages of the new process) image downloaded from RUVID website

If you do have the Spanish language skills you can read the article as it was written originally here.

I have from time to time (in my Sept. 20, 2010 posting and Oct. 26, 2009 posting) featured a different nano art restoration technique as it’s practiced by Piero Baglioni’s (Correction Mar. 1, 2013: Name was changed from Pier Baglioni) team on projects in Mexico and Italy. Baglioni and his cohorts use a technique involving a micro-emulsion partially derived from cellulose. From an Oct. 26, 2009 article written by Michael Berger on Nanowerk,

The solution developed by Baglioni and his team has been to develop a micro-emulsion cleaning agent that is designed to dissolve only the organic molecules on the surface of a painting or other artwork. This emulsion is not only suitable for removing the aged coating on paintings but also for the removal of aged organic varnishes from the surface of easel paintings or gilded surfaces, as an alternative to gels traditionally used in conservation.

The cleaning agent is made by dissolving the volatile solvent p-xylene in water and thickening it into a gel with hydrophobically modified hydroxyethylcellulose (hmHEC) – a gelling and thickening agent derived from cellulose. This oil-in-water emulsion has a microstructure of tiny droplets of oil-coated water trapped in the cellulose chains, and these will dissolve organic polymers on the painting’s surface, thereby restoring the original, clean finish.