Curator’s Advent. Day 10. Relative humidity

Image of a beach. Relative humidity on a warm sunny day with a light breeze is just about right for humans but can be iffy for some objects

Relative humidity on a warm sunny day with a light breeze is just about right for humans but can be iffy for some objects

Mould, corrosion, warping, splitting, delamination, vinegar syndrome, desiccation, off-gassing are all symptoms of poor control of relative humidity and fluctuations in the moisture of the air surrounding a museum object remain the biggest threat to their long-term health and well-being. Too dry can be as bad as too wet. The whirling hygrometer spun purposefully around our heads has been replaced, by and large, by digital and radio controlled monitors. We love to see that 50-55% for paper and wood and 35-40% for iron.  For the curator who does not have the yackers (money) for multiple environmentally controlled zones, or who can’t afford the energy bill of hefty air conditioning units, silica gel has become a friend. Secreted (discretely) in a showcase or in appropriate quantities within the packaging environment, the curator can employ this and a treasury of techniques to keep objects nice and comfy, and presentable.

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