How they got stuck is amply documented. The wall next to the sunflowersthe glass in front Girl with the pearlthe list of the Sistine Madonna, and the talk show table of Jinek: a climate activist glued himself to all these objects.
The videos that appeared on social media and were widely shared only lasted a few minutes and only showed the opening scene. But how the glued-on activists came off safely and the superglue was removed is still a mystery. How do you stop super glue from sticking?
All grooves and nooks
The main ingredient of super glue is almost always cyanoacrylate. It is a substance that is liquid at room temperature. It comes out of a glue bottle like liquid, and gets into all the nooks and crannies it can get into. When it comes into contact with water vapor in the air, a chemical reaction begins. Huge amounts of cyanoacrylate molecules react with each other to form a large long molecule: polycyanoacrylate. That is a solid, and once dried, the long, rigid molecules can no longer move freely.
“To remove this type of glue, you can gently ‘remove’ it mechanically, such as with a knife, or dissolve it,” says Klaas Jan van den Berg. He is professor by special appointment of material aspects of painting at the University of Amsterdam, and a researcher at the Cultural Heritage Agency of the Netherlands. “It is best to use a solvent that dissolves the layer to be removed, but has as little effect as possible on the layer below. With works of art, it is crucial to bring in a restorer as soon as possible, who estimates what needs to be done on the spot.”
The National Gallery in London, the museum where the sunflowers Van Gogh was the target of climate activists, emails that the police came to free the people from the wall. They had an “appropriate item” with them, but they do not know what that was.
“You can use acetone with superglue, but a restorer will be very careful with it,” says Van den Berg. Acetone, which is also often found in nail polish remover, can damage paint. “Acetone does not dissolve superglue completely, but softens it. The long molecules loosen up a bit, the cohesion in the layer decreases, and the glue is easier to pull off.”
Small wooden sticks
Acetone is indeed sometimes used, says a representative of Letzte Generation. This German action group already attached itself to the glass plate for a painting by Botticelli in July. “But usually the police come with more ordinary oils, such as sunflower oil. They untie us with brushes, small wooden sticks and plastic gloves.” Vegetable oils have the same effect as acetone: they loosen the glue molecules a bit.
The Dutch action group of Extinction Rebellion also confirms that special chemicals are not always necessary to free activists. Gluing to fences or asphalt is “a pretty standard part” of their campaign, says a representative. The police usually use cola to release them. Here the acidity of cola is probably disastrous for the glue: this damages the molecules, so that the glue does not stick as well. “Often the police immediately take Coke with them, if they know that it is us. But in less positive cases, rebels are sometimes just pulled loose, whether by accident or not.”