Do paintings suffer from disease?

Biodeterioration of paintings on canvas?

Fernando Poyatos. 

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. 

5 thoughts on “Do paintings suffer from disease?”

  1. I’ve always adhered to the fact that art is safest on the wall (because of physical damage), however now you explain so much more why we should keep our paintings in the open – thank you for sharing this advice. So, do you think it’s better to use acrylic paints rather than oils – to keep the bugs away?

  2. Hi Emma. Thanks for the question. Biodeterioration occurs mainly in rganic substances such as oils, however, in synthetic substances it also occurs, such as acrylics (rich in vinyl resins, acrilic polymers, etc…).The important thing is to have clean andry walls, as well as the backs of the fabrics and the frames.If there is moisture and the insect is xylophagus, be careful with the frame. If there moisture, some microorganisms love acrylics. We recommend 50-55% humidity and 18-22 degrees of temperature depending on the type of work.

  3. Hello Fernando,
    What time frame are we talking here? Is this relevent to artists now, or more of a museum and classic arts gallery?

    Also, does varnishing help?

    • Good morning Marilyn. The time depends on the circumstances in which the works are. Imagine a damp wall and the back of the painting leaning against it. With a simple change of temperature when activating the heating system of the place the damage can take place in a few days. Other times it is slower. I have been to collector friends’ houses and I have dedicated myself to picking up paintings and seeing their backs and in some cases I have encountered this problem. It is not something exclusive to museum or gallery warehouses, it is something very common where there are adverse conservation circumstances and suitable climatic circumstances for the action of biodeterioration. This is very common also in tropical or semi-tropical countries. Regarding clear varnish that helps, but it is also formed by organic substances called terpenic resins in traditional varnishes or synthetic in modern ones. For this reason, where these biodeterioration processes take place most easily is on the surface of the canvas on the front of the painting, because that is where there is a greater amount of cellulose in the textile fibers. This is also why works made of paper, cardboard, etc. are very susceptible. etc … that also retain moisture easily.


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