The restoration of the Sistine Chapel ceiling occurred from 1984-1989. A variety of chemical solvents were used, in conjunction with washings of distilled water, to remove the many layers of candle wax, varnish, and animal glue. Lastly, an application of a solution of acrylic polymer was made to consolidate and protect the surface, along with further washing. The use of microbes to eat away organic residue form the surface of art work was not employed until early in the 21st century.
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Do you have the information on specific works of art that did utilize microbes in the restoration process and what specific microbe was used?
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A strain of bacteria, Pseudomonas stutzeri, was used in 2003 on medieval Italian frescoes. This is the most notable example I have found of this technique being used in art restoration. The resorted painting was "Conversion of St. Efisio" by the 14th century artist Spinello Aretino. You can read more about that restoration here.
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