Wilma discovers: 500 mould spore measurements (and a bug-killing freezer)

In this column, new Director General Wilma van Wezenbeek gets to know the KB. Behind the scenes, she is meeting with employees doing important work that not everyone is aware of. It often involves work on an impressive scale. Today: mould and pest control done by the Collection Preservation department.

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No one wants mould or silverfish in their house. At the KB we’re particularly keen on fending them off, as mould and insects could have a disastrous effect on our collection. Fortunately, we have employees who spend their days combating harmful influences like these.

One such employee is Aicha Hockx from the Collection Preservation department, who I met this week. It was nice to meet a colleague who, like me, has not been working at the KB for very long. Aicha told me that carrying out 'airborne germ count measurements' is part of her job. In other words, it concerns measuring the number of mould spores in the air. About 500 measurements were done in 2023. 

"Our warehouses are designed to combat mould by, for example, maintaining an average humidity of around 50 per cent. But unfortunately sometimes mould is still able to form due to a variety of reasons, such as a water leak. The measurements tell us whether we need to take action. When everything is going well, I have the most boring job in the KB because that means there’s nothing that needs to be acted upon."

So there were 500 measurements taken in 2023. That sounds like a lot. "We conduct two big measurements every year,” Aicha explains, "where we get readings at 150 locations throughout the KB. So that’s already 300 measurements by default. In 2023, we had a leak, which resulted in having to take 200 extra readings, 9 to 15 times a week, for consecutive months. This allowed us to chart the developments."

Silverfish

And then there are insects like silverfish. "If everything is running as it should, our warehouse is set up so that these bugs don’t stand a chance", Aicha says. "For example, our cabinets are on legs, so the silverfish have to climb to reach the books. That’s not possible in our case, because silverfish need a rough surface and our cabinets are made of smooth aluminium. There are also sticky traps set up at various places in the repository. The sudden appearance of 30 silverfish in a trap would for instance be an indication that something is not right, which is when we’ll investigate the cause. We would then need to rule out that the insects are coming in through a hole in a wall, or something."

But how do we prevent hazards such as mould or insects from entering in the first place? The KB has a quarantine room where all previously owned books are taken prior to being allowed into the repository. Aicha examines each book for damage and tests every one that is suspected of having mould. In case of a positive result, the mould has to be killed using radiation. Books containing insects are put in the freezer because bugs can't withstand the extreme cold. If the book is made of special material such as parchment, Aicha consults with a conservator on the best treatment. Not all materials cope well with the cold. 

Aicha and her colleagues hope to use all their acquired knowledge for our new book repository. "By knowing how everything is connected, for example how climate affects our collection, we will know exactly what to do to keep our collection safe in the future."

I have every confidence in that. Meanwhile, I secretly hope Aicha's work remains very boring for now. 

Wilma van Wezenbeek