It’s been cold – below zero – in the UK the last few days, with days more chilly weather to come. I’m keen to have warmer weather (unless there’s snow coming, in which case bring it on) and it’s a sure thing that if you’re storing collections and archives in basements or attics, they’ll be suffering too.
Why? How can cold cause problems? I’ll use an analogy from last week. My seven year old wanted to take an inflatable plastic globe to school. We rescued it from her bedroom by the radiator and blew it up fully. We set off on foot to do the 10 minute walk in -2 degrees. After a few minutes, we noticed that it had ‘blown down’ and that the feel of it had changed – it had gone from being plump and springy to brittle and hard to move. I explained that it hadn’t blown down but that the molecules of cold air within the globe and the particles of plastic in the globe had contracted in the cold, causing the blown down effect and the plastic to feel delicate. I told her to take it in to the warm classroom and see what happened and later she was able to tell me that the procedure had reversed.
Items in archives and collections react in exactly the same way to differing degrees – and there lies the problem. If you’ve two items together, say books with parchment glued onto paper or buckskin glued to card, they will expand and contract at different rates, causing loosening and tearing. Add a bit of condensation into the mix, which freezes in the layers, and you’ve got trouble heading your way – mould, mildew, shrinkage…
18 degrees is considered a stable temperature for most objects. It is worse to have daily fluctuations than seasonal ones as this causes more expansion/contraction cycles. Any area getting down to near freezing temperatures is a cause for concern. If your collection is in a poor space, consider a long term insulation plan with false walls of battens and foamboard – this will help with heating costs in the rest of the building. If you haven’t already covered windows, do so, either permanently or with blankets or thermal blinds at the windows. Allow some heating on the coldest days. Keep the area dry at all times. Consider a proper plan to look after your history and take care of your unique collections.