Biodeterioration of paintings on canvas?
Do not worry. I’m not going to write about a pandemic… There is enough to read already. The subject I am writing about is a very specific field within pictorial art. Biodeterioration of works and more precisely the degrading action of microorganisms on canvas paintings.
For conservation science it is still a fairly unexplored subject that does not have an easy solution. The mixture of organic and inorganic substances that are found in the pictorial stratigraphy is so heterogeneous, that is to say so mixed, that microorganisms can act selectively on each of the constituent materials. Bacillus, Aspergillus and Penicillin love animal glues, textile fibres, organic oils, etc. They go crazy on this succulent banquet on linen cloth impregnated with bone glue and linseed oil. All of these act like a dressing on a salad.
These organisms are made more abundant by the absence of light, poor ventilation and surface dust that together with the textile fibres retain the humidity of the wall where they are exposed. This is a great problem for conservation in historic buildings and in many cases this action goes unnoticed until the damage is well advanced and irreversible.
A life of its own
How many times have we heard in an exhibition or in a museum the phrase… “this painting has a life of its own”. Well yes, literally sometimes they do. At the macroscopic level we can find some superficial stains that warn us of this activity, both on the front between the crackle of the varnish, and on the back of the canvas. When we view the work at a microscopic or ultramicroscopic level. What a surprise! Yes, there they are… with their long hyphae and spores devouring the feast and becoming part of the pictorial structure.
Fungi, moulds, bacteria and yeasts are responsible for transforming organic matter and metabolizing it for growth. Some are even capable of feeding on inorganic matter such as preparation layers and pigments. As they metabolize these materials to feed we can find them literally glued to the textile fibres of hemp. A fibre widely used in historical Spanish painting not in the modern context in which it is mostly experienced here on the Alpujarra terraces.
The activity of these organisms is very destructive and its eradication is complicated. The use of biocide treatments on the work of art can also cause irreparable damage. The best solution as always is preventative rather than curative. Avoid the appearance of these organisms by carrying out environmental control and maintenance tasks. Cleaning periodically helps. Museums filter the air and control the temperatures and humidity.
What to do
We should all keep this in mind. Do not underestimate how badly damaged work can get, keep your works of art in good conditions if you want them to be durable over time. Otherwise you could be growing a garden on your works. So better perhaps to keep that outside and enjoy it there.
My name is Fernando Poyatos and I am one of the latest artists to become a member of ANA, Artist’s network Alpujarra. I am a specialist in art restoration and preservation and I hope you have enjoyed this small slice of the work that goes on behind the scenes.