We may have cheated a little with this entry, but we felt it was a good excuse to tell you a little more about what goes on ‘behind the scenes’ inside the repository.
What are the repositories?
Repositories (or strong-rooms) are the temperature and humidity controlled spaces which store all of the records we hold here at Dorset History Centre. They consist of large spaces, filled with shelving units on which sit the thousands of boxes of content, going all the way back to 965 AD.
Dorset History Centre has three repositories, one of which is a specialist space for storing audio-visual content.
How big are the repositories?
Big.
Big enough to have about 8 miles of shelving.
What are the conditions like in the repositories?
Repositories for archival material have to be cold. Typically our repositories are around the 14 °C mark, which is within the recommended range for storing old documents. They are also humidity controlled, as the humidity can also affect old documents! If the air is too damp, there is a greater risk of mould damage and both paper and parchment will begin to absorb moisture and expand. Our repositories therefore have keep the humidity at a constant level of around 45 %.
How?
Both the temperature and the humidity are controlled through a series of pipes and units, alongside visual monitoring aids to help us monitor for any problems. These pipes line the ceilings inside the repositories.
What’s so special about the audio-visual repository?
Cassettes, VHS tapes, DVD’s, minidiscs, betamax tapes, and photos all need to be stored at lower temperatures and in slightly drier conditions than other paper or parchment. Most people have seen faded photographs, or film recordings, a result of the long-term instability of the material on which they were produced. The AV repository helps to look after these documents in a colder environment than the other records, and holds off some of the worst fading. Some old film also can also spontaneously combust, so it’s better to keep all of this material in a colder environment!
But really, how big are they?
Big enough to hold over 50,000 boxes.
Big enough to let us measure a 48-feet long document in staff units.
If you want to know more about how the repositories work, feel free to ask any of the staff who will be more than happy to tell you about the space!