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.

Published 2022-08-11

Halland Art Museum is beautifully located next to Nissan and Norre Katts Park in Halmstad. Here visitors can enjoy exhibitions and exciting events. A few years ago, the museum underwent a major refurbishment. The house was renovated and an extension added with the entrance facing the city. As part of this work, the museum invested in measuring equipment to monitor temperature, humidity, carbon dioxide and light in different spaces.

A total of 20 testo 160 WiFi data loggers were purchased by Stefan Kjelberg, the store manager, to monitor the indoor climate at the art museum.

Why do you want to measure temperature, humidity, carbon dioxide and light?
– Because the art we have is sensitive to temperature fluctuations and because a lot of light over a long period of time damages paintings. For example, if it is too dry, the wooden frames of the art can twist or shrink, which in turn can damage the painting.

Where are the measurement boxes located?
– We measure in the exhibition halls and in our art warehouse. I also have two testo 160 IAQs in public spaces to monitor the CO2 content of the indoor air, so that the air is not too bad for visitors.

What are your impressions of the measurement system?
– I am very happy with the system! It’s nice to have a cloud service that gives you an overview of all the devices in the house.

Is the cloud service working well?
– Yes, it works well. If I had a complaint, it would be that you can’t see averages in chart mode. It’s usually the average value that we want to be stable so that we don’t get too large fluctuations in, for example, humidity or temperature. So we mostly choose to look at the values in table mode, where it is possible to see averages.

How many measuring points do you have?
– We have 20 measuring points where we have installed data loggers of the type testo 160 TH (°C and %RH), testo 160 THL (°C, %RH, lux and UV) and testo 160 IAQ (CO2, °C, %RH and mbar).

How do you use the logger system in practice?
– During installation, all data logs were registered in the cloud service. After that, all you have to do is log in via the web interface to see the current measurement data from all 20 measurement points.

– We have four different ventilation systems with external sensors around the museum. By setting up the testo 160 loggers alongside these sensors, I can follow all the readings at these points.

– When I see that the measured values are not optimal, I can control all four installations via a dedicated web interface and cool, heat or humidify the premises. So I have full control of the indoor climate!

Does the monitoring of the indoor climate cause any disturbance to visitors?
– As we have mostly white walls everywhere in the art galleries, the logos blend in very well. We have also purchased covers for all logs that can be painted, if necessary.

Has a temperature alarm or something else exciting happened?
– No, unfortunately I have no exciting alarms to tell you about, but we have a refrigerated magazine for photography and in there I have put a testo 160 THL. It has helped us a lot in getting the right climate in the cooled reservoir and in the lock.

How did you monitor the indoor climate before?
– We used to have standard data loggers that you had to walk around and read manually, which was very time-consuming. We also could not see any real-time metrics.

– Thanks to the Testo cloud service, we can collect measurements automatically whenever we want. I’ve set them to measure once an hour and send the data to the cloud once an hour, so now you can adjust the temperature and humidity in the rooms pretty much immediately if you need to.

Do you have plans to expand the system?
– Yes, more logs may be needed. For example, I would like to put logs in our external magazine as well. However, we cannot change the temperature and humidity as well as in the museum. But I could get a good picture of what the climate is like there over time.