Whether your painting is damaged or not, it is almost certainly dirty. The level and type of soiling will depend on how it has been displayed or stored; whether it has been varnished; and what kind of surface texture it has. Ultimately the contaminants will cause damage to the paint and to its support. Cleaning the surface of the painting will not only bring it back to life but also preserve its life over the years to come.
Before cleaning, your painting restorer will probably want to determine if the surface has been contaminated with dirt or grime. Commonly these terms are used interchangeably in the general context of cleaning, but they are actually different. And that difference matters to how your painting should be treated.
Is it Dirt?
Dirt is identified as loose, usually dry particles such as dust, pollen, skin cells or soil. It can be organic or inorganic, and it accumulates over time. The conditions of the environment in which the painting is kept have a big impact on the nature of the dirt and the speed with which it accumulates.
For example, if your painting has been stored in a basement or attic then it has probably been exposed to high levels of humidity. Humidity creates the perfect environment for dust particles to stick to the surface of a painting. For art that is displayed in areas that have high levels of human traffic, skin particles will accumulate and soil the surface. Geographical locations near heavily used roads or rooms where fires and candles are used all contribute to a unique dirt profile of any paintings in the vicinity of these pollutants.
Or Is it Grime?
By contrast, grime is identified as a greasy film that is a blend of oils and other substances. In the context of painting conservation, grime is soiling that has become embedded in the paint itself. It’s harder to remove than the dry particles of dirt, which are more superficial than grime, and it can leave a painting looking dull or discoloured.
As with dirt, the surrounding environment is responsible for the accumulation of grime. Factors such as moisture in the air, heat and human activity in the vicinity are likely to contribute to the build up of grime on your painting’s surface. Grime can be more damaging over the long term than dirt as it often contains bacteria and micro-organisms that will attack the surface and that can sometimes be a hazard to your health.
Why Does it Matter?
The difference between dirt and grime will matter very much to your picture restorer who will be aiming to clean your painting safely and effectively .
Your restorer will be able to remove dirt particles fairly easily and with minimal stress to the painting. Dirt may obscure the composition, but it rarely causes damage to the integrity of the artwork. Often it can be gently removed with a soft brush or cloth or with a specially adapted low-suction vacuum.
If the picture restorer has identified grime then brushing and wiping will not be effective and a different approach to cleaning will be required. Cleaning agents and solutions will usually be necessary. Choosing the right agent is a balancing act between minimising the risks of chemical damage to the paint, its canvas or panel and removing the grime which also threatens the painting if left untreated.
So, in a nutshell dirt consists of dry organic or inorganic particles, while grime is a greasy, sticky substance formed by the blending of oils and dirt particles. The difference between the two matters to your painting restorer because the nature of the contaminants will determine the tools and the methods which he or she will employ to clean your painting.