Enhanced climate monitoring of priceless objects

Published 2024-05-17

An important part of the work of conservators Augusta Persson and Ann-Sofie Stjernlöf is to take preventive measures to ensure that the historical objects in the museums’ care are not damaged. At the Livrust Chamber, remote monitoring of temperature and humidity is being strengthened. The same applies to the Swedish Museum of the Holocaust, where there is also a special focus on light measurements.

The Armoury and the Swedish Holocaust Museum are two of a total of seven activities run by the National History Museums (SHM). The indoor climate in these environments is something that occupies a lot of time for SHM’s nine conservators.

– Ensuring the right climate is a very important part of working with preventive conservation. Above all, it is about having as even a climate as possible. In several places we have objects that are unique and priceless, which places high demands on the climate,” says Augusta Persson, head conservator at the Armory.

Optimal moisture level: 40-60 percent
Factors such as temperature and humidity must simply be within certain carefully specified ranges. Otherwise, there is a risk of irreparable damage to museum objects such as metal, wood, textiles and paper. Organic material should preferably be stored in an environment where the moisture content is between 40 and 60% with a maximum daily variation of plus or minus 5%. The exception is paper, which benefits from a slightly drier climate.

– Often you have different materials in the same environment. It is important to find a middle ground and above all to ensure that the values for temperatures and humidity do not fluctuate so much, says conservator Ann-Sofie Stjernlöf, who has the main responsibility for the Swedish Museum of the Holocaust.

SHM strives to be coordinated and have common routines around the management. Not least when it comes to prevention. All conservators should be able to stand in for each other and check measurements, for example. To make this easy and convenient, it has been decided to invest in the same type of wifi data loggers from the testo 160 series for all seven museums. The Livrustkammaren is the last museum where these logs were recently installed.

Ann-Sofie Stjernlöf checks her mobile phone and quickly gets a picture of the indoor climate in the Swedish Holocaust Museum.

Extra measurement in six small booths
– We already have a comprehensive climate monitoring system at the Armory. The latest equipment purchased in the form of data loggers will complement this monitoring, says Augusta Persson.

The logs are for the basic exhibition on Sweden’s royal history. In six smaller stands there are selected, unique objects that you want to highlight a little extra. These include Gustav Wasa’s crowned helmet, a Pandora doll from the 1590s that may have belonged to Maria of Palatinate, married to Duke Charles (who later became Charles IX), and a bloody sheet in which Gustav II Adolf’s embalmed heart was kept.

– There is a moisture system with built-in logging in each booth, but it takes a lot of time to open and read these readings. At the same time, by opening them from time to time, we risk destroying the climate in the stands. We therefore felt that we needed a wireless and connected measurement that allows us to quickly and easily monitor the climate in the stands remotely,” says Augusta Persson.

In the larger exhibition stands, there is overpressure and constant air exchange to prevent impurities in the air. Light meters have also been installed there. Light measurement in particular is something that Augusta and her colleagues will review and probably expand in the future. More and more museums are shifting light-sensitive objects in long-standing exhibitions based on how many lux-hours they are exposed to.

Glass facade lets in lots of light
Measuring light is also a priority at the Swedish Holocaust Museum, says Ann-Sofie Stjernlöf. The museum’s exhibition, called ‘Seven Lives’, opened in June 2023, depicts people who were affected by the Holocaust in different ways. Clothing, photos, documents and letters are displayed in carefully climate-controlled stands.

– It is the first exhibition we have in this building, which has a large glass facade and lets in a lot of light. Although the stands are not in direct sunlight, we have invested a little extra in measuring both UV and Lux to keep track of how much light the objects get on them.

Ann-Sofie Stjernlöf says that the exhibition leaves no one indifferent. The contents of the stands make a strong impression on visitors.

– A costume from a concentration camp, for example, is quite… striking, says Ann-Sofie Stjernlöf.

Bloody garments and fancy dresses
Inside the Armory, both bloody garments and festive clothes arouse great interest. Everything from Gustav II Adolf’s clothes from the Battle of Lützen and Gustav III’s costume when he was murdered at the masquerade ball to ceremonial costumes from coronations and weddings. These include Sofia Magdalena’s court dress with a stiff skirt, which she wore at her wedding to Gustav III.

For Ann-Sofie and Augusta, the work of mapping the climate in different areas of the museums continues.

– “Once you start measuring and seeing results, you get good guidance on what needs to be done in the future,” says Augusta.

She says that they have recently reviewed the lighting in the carriage hall of the Livrust Chamber’s main exhibition. Sensors have been installed so that the light only comes on when visitors move around the space, thus protecting the objects from fading.
Both Ann-Sofie and Augusta repeatedly emphasize the importance of continuously logging the indoor climate to ensure optimal conditions for all museum objects.

– Our job is to preserve these objects for all time,” says Ann-Sofie Stjernlöf, to which Augusta Persson adds:

– The objects will help you understand a little better. Events become more tangible and you get closer to the story.