Shortly after 8 pm all the media installations suddenly fall silent and the circles of chairs in the Palmenhain (“circle of enlightenment”) are empty. As the sun sinks behind the Aue and the last documenta 12 visitor leaves the exhibition, the most important part of the working day begins for the Aue-Pavillon’s custodial staff and usually continues until 11 pm or even midnight. Comprising a staff of 10, working two shifts a day, the crew, led by Mathias, is responsible for maintaining the Pavillon and its arts works. In the period prior to 10 am and after 8 pm, their daily duties consist of cleaning the display cabinets and the glass, dusting down the art works and the walls and applying dabs of fresh paint to the walls and floor, in addition to a number of regular special tasks.

First, the grass on Ines Doujak’s work Victory Garden is watered or rather inundated. Twice weekly it receives some 80 litres of water within 10 minutes. And every two or three days the grass is cut using a hand mower – a task incumbent on the tall figure of Mathias, which he begins at 8.35 pm: “You need long arms to do this”, laughs the team leader and qualified architect, as he stretches over the bed to make sure he reaches every blade of grass. After three-quarters of an hour, the job is completed. As Mathias trims the grass and the Pollyanna vine, he reveals his secret formula: “The Pollyanna vine must be watered differently from the grass, namely not from above. You have to lift up each one slightly in order to water them from beneath.” Initially they would wither far too quickly and were always having to be replaced. But now Mathias has got the knack of it – leaving him with a shed full of spare plants which are no longer needed. Finally, the seed packets are covered as protection against the dust and the ultraviolet light used to irradiate the bed overnight to encourage growth. The smell of freshly mown grass now permeates the Aue-Pavillon.

No one is permitted as close to the “treasures” as the members of the custodial team. You have the impression that each art work has its own personality and quite distinct characteristics. Comprising architects, conservators and skilled workmen, the team has devised a special formula for each of its charges. One senses that they have developed a very different relationship to the objects, much more direct and intimate than a visitor in search of great art. And yet they treat each one of the fragile icons with great care and respect.

When darkness begins to fall at around 9 pm, a security guard switches on additional neon lights. In the darkened, partitioned room featuring the work by Saâdane Afif sits the amateur musician Uwe on an upturned crate whose markings betray the nature of his job: “Guitar tuner’s seat”. Normally, he tunes the strings every two days, but today he is instructing his holiday representative, Oliver, also a musician and fellow team member. Uwe monitors his progress, commenting with satisfaction: “He’s doing a fine job!” Next door, Katrin is retouching the floor with red paint and her colleague Christian is chasing balls of wool along the temporary wall panels. “And I can proudly state: this is my speciality!”, he laughs. His efforts are necessary because the cleaning crew, which dusts and hoovers every morning, is only allowed to approach within 50 centimetres of the art works. At the same time, Christian is gathering up the debris – sometimes even the messages – left by visitors. Once, he explains, someone discovered a squeaking toy-giraffe in Ines Doujak’s bed.

From 11.00 pm onwards, the Aue-Pavillon is shrouded in silence. The custodians depart and won’t return until 8 am next morning, leaving their charges all alone, save for the purring of the air conditioning system, which will remain in permanent operation until the end of September.

Next morning, the exhibition room appears as tranquil as on the previous evening. The guitars and the media installations are still silent. Katrin and Christian are assigned to work the early shift from 8 am to 10 am, and some duties can only be performed during the hours of daylight. First of all, however, there is the special task of replacing the three-day old, already rather crumbling pieces of cake on the small platform of Mladen Stilinović’s installation with fresh “exhibits”. Working to precise instructions, Katrin has already purchased a fresh cake from the baker on her way to work: “It's not to be a fruitcake, but a fruit tart”, she explains, as she starts cutting the tart into small squares.

Then the process of removing the protective covers from the seed packets begins, of dusting the labels, hoovering the floor, arranging the countless Ai Weiwei chairs into rows and checking them to ensure they are all in tact. Katrin once again repositions the cushions in the Basbaum installation which were pushed to one side for the cleaning crew. This alone takes up to 15 minutes. The carpet underneath the cushions has worked itself loose and is reattached with a special adhesive.

At around 9 am, all the chairs are in place and the first inspection is made. As a member of the cleaning crew polishes the entire floor, Christian is using the clear morning light to carefully examine the walls and the floor for imperfections. Even a curtain drawn back mere centimetres too far, catches his roving, beady eye.

At 9.11 am the guitars and all the media installations suddenly sound off together. The media technician, who walks through the Pavillon every morning operating everything with just two remote controllers, is nowhere in sight, but his progress through the exhibition can easily be traced from the din of video and sound installations which successively roar into life.

As nine-thirty approaches, everything is ready. The grass on the Victory Garden seems to have grown overnight and greets the new day and the new visitors with a well-manicured appearance. Shortly before 10 am, an army of wardens invade the exhibition room – the sign for everything to start. From now until 8 pm the exhibition once again belongs to the visitors who - oblivious to the nocturnal activities of the “elves” – find everything spic and span.