Clad in Bark

New materials from the timber industry’s waste

The models are wearing bark. Her jacket’s been woven from little pieces of pine bark, while his has been sewn together from a single piece of the same material. Charlett Wenig and Johanna Hehemeyer Cürten are the creators of this fashion innovation. And these jackets are not the only items from tree bark that they have designed and produced. A skirt and high heels, sandals and an ankle boot soled with robinia bark complement their collection.

Nothing but plastic

During her industrial design studies, Charlett Wenig grew tired of working over and over again with the same industrially produced materials – mostly plastic. Then she found someone of like mind in Johanna Hehemeyer Cürten from the Weißensee Academy of Art Berlin. “I started out experimenting with bones,” says Wenig, who works at TU Berlin’s Institute of Material Sciences and Technology and the Max Planck Institute of Colloids and Interfaces in Potsdam and whose doctoral thesis examined bark as a material. “I wanted to work with material that didn’t have to be newly produced, preferably a waste product, in order to be as sustainable as possible.” That’s how she came across bark – a waste product of the timber industry, which is generated in huge quantities and is either burnt or, in the best case, ends up for sale as mulch in garden centers.

Coloring agent in glazes

It was obvious to Charlett Wenig and Johanna Hehemeyer Cürten that they would begin by designing clothes. Since bark is the skin of the tree, they wanted to know whether it could also become a kind of skin for humans – and they were curious about how it would feel to wear. Their first attempt failed. The jacket was like a suit of armor, stiff as a poker. This is why a key element of their research is to examine the bark’s properties in order to deduce processing methods and possible applications. And not every type of bark is the same. In the laboratory, Wenig is now analyzing the bark of five tree species – spruce, pine, oak, larch and birch – with regard to density, structure, thermal conductivity, crushing and breaking strength, as well as reaction to water. Initial results have shown that pine is very flexible and can be woven, that the resin content of all five types of bark means they can be easily compressed into sheets through heat and pressure alone (and without additional glue), and that birch could be suitable as a coloring agent in glazes.

Hellishly difficult work

Charlett Wenig has to go out and forage the bark she needs herself. To do this, she heads off into the woods. The only suitable time to peel the bark is in spring, she says, when the trees are “full of sap” and sprouting their first leaves. Beforehand, however, she must find out from the forester whether trees have been newly felled. “You’re not allowed to peel the bark off a tree while it’s still alive, because then it dies. You can only do this with trees that have already been felled.” And what stops her from getting the bark she needs from the lumber mill? “They peel it off in a way that doesn't suit my purposes. They scrape the bark off the trunk from top to bottom. But I peel it off from around the trunk. A hellishly difficult job,” she says.

Moving away from well-trodden paths

In her doctoral thesis she wants to make judgments about which of the applications – on the basis of which material properties – are conceivable and explain why she thinks a training in natural sciences should be more strongly included in design studies. It’s hardly surprising that plastic is so dominant in the industry when designers know so little about natural materials. “As designers, we need to gain a deeper understanding of the structures and properties of natural materials, and only the natural sciences can provide us with that,” says Charlett Wenig. With this knowledge, the design industry could move away from its well-trodden paths.

Original publication

This text originally appeared in German on 29 November 2020, in the Tagesspiegel newspaper TU Berlin supplement.

Author: Sybille Nitsche