All types of objects are affected by one or all of the agents of deterioration, and photgraphic materials are no different. Photogrpahic matrerials are most sensitive to the incorrect tempertautre and relative humidity, light and air pollution.
Light causes the images to fade leading to eventual loss of the image. Some photographic process will result in fading occurring more quickly as they are more light sensitive than others. Ultraviolet light is the most dmagaing part of the light spectrum and so must be ellimated from the location a phptpgraph is to be displayed. This can be done by applying a special film on to the window glass that anbsorbs the UV out of the natiral light coming in. While on display photographic materials should not illuminated above 50 lux and they should not be left on permanant display.
High and fluctuating temperatures exacerbates image fading and accelerates the rate of deterioration. Similarly with relative humidity high and fluctuating levels cause the most damage. Physical and chemical damage will occur if the environment is too humid, and if too dry physical damage such as cracking, fissuring, peeling will occur. Different types of photographic materials should be stored at different temperatures:
- Subzero (-20º – 0 ºC): Cellulose nitrate, cellulose acetate, early colour film & prints
- Cold (0º – 8º C): otherfilm based negatives
- Cool (8º – 16º C): glass/metal based photos
- Room (16º – 23º C): well processed black and white prints.
Pollutanats from both the environment, storage materials and the photographs themselves can cause deterioration. Pollutants can cause yellowing of prints and oxidisation of silver. Photographic processes that use cellulose acetate can give off acetic acid when they are degrading. The following methods can be employed to prevent damage by from pollutants:
- Reduce pollutants by using filters if possible
- Increase air movement to avoid microclimates
- Use good quality housing to mitigate effect of poor air quality
As if all of the above wasn’t enough to cause deterioration there are biological and physical factors to add in to the mix too! Mould and pest insects can cause damage:
And then there’s us of course! Poor handling, storage and display can all lead to physical damage, inlcuding breakages and tears.
Preventive conservation housekeeping plays a key part in looking after photographic materials, as it does with any collection. Here are some of the basic steps that should be taken:
- Keep research and storage areas clean. Use a vacuum fitted with a HEPA filter
- Regularly check for mould, insect or rodent activity
- Avoid using household cleaners
- Place away from heat/water sources (e.g. radiators)
- Do not store photographs near photocopiers
- Avoid using carpets in storage areas if possible
- Do not store photographs in freshly painted rooms
So in summary, some key points to remember for the care of photographic materials:
– Get to know your collection;
Identify the different photographic processes in your collection, particularly those susceptible to degradation.
- Handle items correctly;
This is one of the main causes of damage to photographs but one of the easiest to mitigate.
- Monitor the environment – and improve where needed;
Be aware of poor quality primary enclosures and containers, other possible contaminants and biological activity. Monitor environmental conditions to ensure they’re suitable.
- Carry out regular condition checks;
Monitor the condition of the collection regularly, consulting a specialist conservator if there is cause for concern.
Alex, Emily, Lucy, Melinda, Sarah and Zena