The art of protecting artwork
Thanks to modern technology, the collection in the Bauhaus Museum Dessau is safe from fire.
Paintings, sculptures, and furniture are perishable objects. The Bauhaus Museum in Dessau, Germany, which celebrated its opening in 2019, is an example of how technology can be used to effectively protect cultural treasures in a modern building and preserve them for posterity. Siemens technology is making a significant contribution.
Since September 2019, Dessau, Germany has had another landmark. The new Bauhaus Museum houses over 1,000 objects from the famous art academy, including student works and teaching documentation as well as drafts and prototypes from the workshops. “For the first time, we can exhibit our foundation’s extensive collection publicly, in the heart of Dessau,” says Frank Assmann, head of the construction department at the Bauhaus Dessau Foundation.
Founded in Weimar, Germany, in 1919, the Bauhaus moved to Dessau in 1925. Anyone strolling through this city in the state of Saxony-Anhalt today walks past many buildings and squares where, over the course of many years, masters and students of the renowned art academy lived, worked, and spent their free time. This means that the new museum stands on historic ground – and it has also been well received, with up to 1,000 visitors pouring through the 5,000-square-meter building every day.
Treasure chest in a concrete block
Naturally, the new museum’s architecture is based on the Bauhaus style. Architect González Hinz Zabala of addenda architects from Barcelona, Spain designed an elongated concrete block that appears to float inside a glass envelope. This “Black Box” is easily recognizable from the outside. This “treasure chest” contains many valuable exhibits from the collection of the Bauhaus Dessau Foundation, which maintains more than 49,000 objects from the art academy and has the second-largest collection of Bauhaus art in the world.
In Dessau, visitors can view and admire objects from all phases and disciplines of the Bauhaus, including furniture, lamps, fabrics, and other works of art. None of this would be possible without the modern technology that protects the sensitive exhibits from external influences. "To prevent any changes or deterioration, we have to maintain constant, unvarying climatic and lighting conditions,” explains Assmann. “Even short-term deviations can negatively impact the exhibition pieces.”
Art under stress
Damaging external influences on cultural objects can be divided into four categories: energetical, biogenic, chemical, and mechanical. Mechanical stress is mainly caused by temperature and air humidity. Fluctuations in these values cause materials to expand and contract, destroying their internal structure over time. Among the materials affected are oil paint, stone, and wood. In the case of latter, the cell structure can even collapse permanently.
To prevent any changes or deterioration, we have to maintain constant, unvarying climatic and lighting conditions.Frank Assmann, head of the construction department at the Bauhaus Dessau Foundation
That’s why professional climate control is so important in museums, although some compromises have to be made. Organic materials are healthiest at a relative humidity of between 45 and 55 percent, whereas metals prefer a dry climate and are best protected from corrosion at a relative humidity below 30 percent. While most materials can be correctly stored at temperatures from 18 to 20° Celsius, synthetic materials prefer a colder environment between 12 and 15° Celsius.
“Ideally, there should be different climate zones for the different objects,” says Professor Alexandra Jeberien from the University of Applied Sciences in Berlin. “But it becomes more difficult when, for example, you have a chair with a tubular steel frame and a leather seat. For a composite object like this, you base the conditions on the dominant material and try to find the best mean values in terms of temperature and humidity.”
Protection from UV light
Light also has a major impact on works of art. The ultraviolet component splits chemical compounds, resulting in the destruction of things like color pigments and carrier materials. Objects in storage are shielded from light, but in the exhibition space they’re protected by modern technology. Today LEDs are the lighting of choice because of their low blue-light content. UV filters on LEDs or display cases provide additional protection. The amount of light can also be reduced, for example, with sensor-equipped lighting that switches on only when a visitor is near an exhibit.
Undesirable chemical reactions are mainly caused by atmospheric oxygen, although nitrous oxide and sulphur dioxide can also damage exhibits. For example, the combination of light and oxygen can cause oil paintings to lose elasticity and become brittle. “That’s why we reduce the atmospheric oxygen content in warehouses to 16 percent instead of the normal level of around 21 percent,” says Stefan Wülfert, head of the conservation and restoration department at the University of the Arts in Bern, Switzerland.
However, there’s another danger lurking in both warehouses and exhibition rooms. Volatile organic compounds (VOCs) can be emitted by the building shell, packing materials, cabinets, and shelves and can, for example, cause metal objects to corrode. The only solution is to take constant measurements and use VOC-free materials as much as possible.
Insufficiently protected electrical systems can have devastating effects, above all in museums that house irreplaceable artifacts.Frank Assmann
In addition to these chemical and physical factors, biology can also be the enemy of artwork. Mildew and bacteria thrive under conditions of high humidity. In addition to these microbiological hazards, other threats include woodworms and the long-tailed silverfish, which has recently made its appearance in Germany. Again, storing artwork at a moderate temperature and humidity level helps. In warehouses in particular, damage often goes unnoticed for some time, because the objects are packed so tightly together and aren’t under constant observation. International loans are another source of danger, because they can carry insect eggs or fungal spores. An infestation can often be combated with a heat treatment or by withdrawing oxygen and replacing it with nitrogen.
Fire protection has priority
There’s another danger that threatens visitors and exhibits alike: fire. It’s the reason that a safe electrical installation is so vital in museums. Over 30 percent of all building fires are electrical in origin, and one-third of these fires can be traced to the electrical installation. “Insufficiently protected electrical systems can have devastating effects, above all in museums that house irreplaceable artifacts,” says Assmann. “The safety of visitors and employees and our art treasures is our top priority.”
Thanks to modern Siemens technology, the Bauhaus exhibits and visitors to the museum are both optimally protected. Residual current protective devices (RCCBs) and miniature circuit breakers (MCBs), plus a total of almost 260 arc fault detection devices (AFDDs) from Siemens ensure the safe operation of the more than 500 circuits. These protection devices prevent electrical accidents and fires. The AFDDs continuously measure the high-frequency noise of voltage and current on the line (intensity, duration, and gaps in between).
A micro controller analyzes these signals and if anything unusual is detected, it triggers the disconnection of the connected circuit within fractions of a second. “We’ve already had good experiences with Siemens protection devices, and especially with the arc fault detection devices, in similar setups,” reports Jens Funcke, master electrician at Elektro Schulze GmbH, which handled the electrical installation. “They function perfectly, take up minimal space in the distribution board, and are extremely easy to install.”
Always the optimal climate control range
Siemens’ Desigo PX building automation and control system ensures an optimal climate in the museum. It controls the cooling system, the ventilation system, and the water supply. “This enables us to reliably comply with the specifications of the conservators: a temperature of 21° Celsius, give or take a degree, and a relative air humidity of 55 percent, plus or minus five percent,” explains Hartwig Bothe, Siemens’ project manager responsible for the climate control and building management system. “It’s not an easy job, because a lot of sunlight enters the building through the glass facades. That’s why we use sensors to measure the intensity of the sun and can ensure optimal shading of the museum using the curtain controller.”
Intelligent climate control also has to be guaranteed if the main power supply fails. “In this case, SENTRON circuit breakers and transfer control devices automatically switch to the auxiliary power supply. This allows the climate control system to continue functioning without interruption and protects the artwork,” says Stefan Krause, who handled low-voltage power distribution and the power supply protection concept on behalf of Siemens. He took a special interest in the project. “As a native of Dessau, protecting the Bauhaus exhibits was a personal priority.”
Author: Christian Buck
Picture Credits: Siemens AG
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