Museum Assistant Sophie doing a spot of environmental monitoring in the galleries

Monitoring Our Collections

Thursday, March 7, 2013

Behind the scenes today, Museum Assistant Sophie has been checking the environment of the galleries here at the museum.

What is termed “environmental monitoring” (for obvious reasons!) is all part of the museum’s preventive conservation plan, i.e. how we can conserve our amazing collections through preventing or limiting those things that can cause them harm.

The environment that we keep objects in is really important, as most objects are affected by the environment. Specifically, the main environmental factors which can damage collections are:

– Humidity (the amount of moisture in the air)

– Temperature

– Light

– Pollution

– Pests

Wax Doll from Bishops Stortford Museum

Our objects are kept inside, and most are in well sealed cases so pollution isn’t something that is a major issue for us, but the other factors could cause problems! As a rule, keeping objects relatively cool (16-25◦C) and dry (40-60% Relative Humidity) is a good idea as both excessive heat and moisture can be damaging (although sometimes if it is too dry or cold that is also a problem!).

Some of the objects in our collection, for example those made from metal, could be really damaged if there is too much moisture in the air, as it could encourage them to corrode. Others, such as our wax doll, would obviously be damaged by higher temperatures.

To check the environment we have monitors set up around the galleries which are constantly collecting information about changes in humidity and temperature.

Environmental Monitoring Device in the Gallery

Every month we can download this data and see what is going on and check that the environment is safe fo rour objects.

We can also carry out spot checks, which we do every week, with our hand held spot checker. This lets us find out information about the temperature and humidity at the time that we press the button for a reading, which is really helpful.

This spot checker also lets us check the levels of light in the gallery, and the intensity of light falling on certain objects.

Light, both visible light (that we see) ad UV (that we don’t see) cause damage to objects, especially those which are light sensitive such as costume, paintings, skins and paper. You will probably have seen how light can damage objects in your own home, maybe curtains which have faded from hanging in the window? Well light can damages our objects in a similar way and can cause colour changes, as well as support other chemical reactions which use the energy from light.

Past light damage to a school blazer. You can see where the jacket has been done up the fabric colour is darker as it has been exposed to less light. Now the object is in the collection, the museum is really careful about how much light the jacket is exposed to.

To stop this from happening, we try to keep our lighting quite low, so you will notice the windows in the galleries have blinds and our galleries are sensitively lit. The costume gallery also has automatic lights, so the costumes only have light shining on them when people are looking at them- which is quite clever!

 Visible light is measured in “Lux”, and generally we try and keep light levels at less than 200 Lux for most of our collection, although sensitive material such as the African furs, or delicate silk dresses in our costume collection would be susceptible to damage above 50 Lux, whilst many of the flint items would not be damaged at all- so it’s a real balancing act. That’s why checking light levels with the spot reader is really important, and can allow us to change the light levels if needed.

UV (or Ultra Violet light) is really dangerous too, and comes from natural light outside, as well as certain bulbs. We try and limit any UV in the galleries to 0 as by using blinds and UV filtered bulbs it is possible to exclude UV completely, and so there is no reason for it to enter the galleries and cause damage.

The costume gallery here at Bishops Stortford Museum. See how the in case lighting is triggered only when someone enters the gallery to reduce light damage to the costumes.
Pest trap set up in the gallery.

The last major environmental threat to objects in the museum is pests, especially those insects which like to nibble our collection for dinner! Insects, as well as mould and fungi, can be a real problem for objects, especially organic objects such as paper, textile and furs, which make a perfect meal for pests. Keeping the galleries cool, dry and clean is a great way to limit pests, as they tend to like warm, damp and dirty conditions.

We also have some pest traps set up around the gallery to monitor the types of insects coming into the museum. Of course some insects, such as spiders, are not damaging to collections at all, but carpet beetles, clothes moths and wood boring insects all pose a real threat. Our volunteer Guy, who is the in-resident pest-trap expert, checks the traps each month to see if any problem pests are in the galleries, but thankfully so far we are safe!

Taking care of our collections is really important, but is also really fun and means we can preserve them for everyone to enjoy. If you are interested in learning more about how museums preserve and conserve objects, our Museum Assistant, Sophie, is giving a talk on Wednesday 13th March, 2pm, on conservation in museums. For more information go to:


Sophie Louise Rowe, Museum Assistant

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