28.2 Work in progress – Anoxia at Uffizi

07/10/11

Anoxic pest-control activity in restoration requires adequate tools and comprehensive knowledge about art works and materials we have to cope with.Dealing with the chest of drawers of grandma is one thing, dealing with an ecclesiastical architecture of the sixteenth century is quite another. That is the case of the 'ciborium' realized by Giorgio Vasari (A.D.1511-1574) for the Basilica of Santa Croce in Florence, a wooden art work of immeasurable value that moved to Uffizi national museum during an important exhibition, titled “Vasari, gli Uffizi e il Duca”.
The level of complexity of the operations depends not only on the historical and artistic value of the artifact but also on its size. With regard to the above mentioned artwork, the restores had to deal with a huge gilded and painted poplar-wood structure (height: 6m, Ø: 2.3 m). The ciborio, designed by Giorgio Vasari in the second half of the sixteenth century is a big altar placed in the major chapel of the Basilica of Santa Croce in Florence. Owing to a medieval restyling this structure and two big gilded angels were disassembled in 1869 and kept inside a chapel. Disinfestation operations were carried out by the company 
Relart of Roberto Buda under the supervision of the scientist Brunella Teodori.
A detrimental attack of xylophagous insects (
Anobidae) had already been detected on the structure of the Ciborioso that, in 2009, they decided to adopt anoxic methodology for treating the angels figures. At that time they did not treat the main wooden structure because of its large size and because of the narrow passages of the chapel.

They got a chance some time later, when the artwork moved to the museum of Uffizi for the exhibition “Vasari, gli Uffizi e il Duca”.
The Ciborio was disassembled into its structural basic components and the restorers could clean and soak the interior surfaces (the not decorated ones) with a solution of turpentine. They decide to assemble the wooden elements and wrap the structure with a 
heat sealed poly barrier film plastic bubble. In order to make the treatment more effective they filled in the interior volumes with plastic bubbles containing nitrogen. Then the nitrogen blown for the treatment could flow in between the 'balloons' and push the oxygen out. 

Here is the description of the procedure, step by step:
  • Stretched a square poly barrier plastic film on the floor (properly sized for the base)
  • Assembled the art work over that film by adding protective devices
  • Wrapped the entire structure with a cylindrical plastic envelope. The 'big bag' was put on the ciborio by means of scaffolds. Then the two parts of the wrapping were heat-sealed together
  • Exhausted the air from the bubble to reduce the volume of gases to be treated
  • Installed the ISOSEP distillation system, connected pipes and exhaust/inlet valves to the plastic bubble, (including a hygrometer and a thermometer for the monitoring of relative humidity R.H. and temperature t)
  • blown the gas in (nitrogen of purity = 99.8 [2])
  • Kept the anoxic conditions running at the same level for 3 weeks in order to kill all the bugs.


We are very grateful to the Opera di Santa Croce and to Professor Brunella Teodori (on behalf of Soprintendenza Speciale PSAE and the Center for museums of Florence) for providing the visual material showing the moments of the restoration sponsored by the committee of the exhibition “Vasari e gli Uffizi”.

Notes:
1. ISOSEP is produced by ISOLCELL and distributed by C.T.S. Srl
2. In order to lower the level of oxygen down to 0.3% and to get relative humidity R.H.= 50%,the treatment took 40 hrs. During the operations, the average t in the bubble was the same of the museum rooms (~26°C)
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