How Alvar Aalto bent birch into an L and made Stool 60

An architect, a carpenter and a bent birch leg that still holds up a stool.

By Made Over Weekend · 3 min read

Alvar Aalto was an architect, but some of his best known work is furniture you can pick up with one hand. In the late 1920s he met Otto Korhonen, who had founded a furniture and building works near Turku, in Finland, back in 1910. Aalto had ideas about bent wood. Korhonen had the workshop and the hands to try them.

What Aalto wanted was a rigid bent piece of wood that could be both the leg and the support under the seat. The two men worked on it together, and in 1933 Aalto patented the L leg. The first product to use it was a simple round stool with three legs, known today as Stool 60.

How it was built

The trick is at the top of each leg, where it turns through a right angle. According to the Victoria and Albert Museum, thin saw cuts were made along the grain of the birch, so the wood could flex there. Sheets of veneer were glued into the slots, and once the glue set, they held the bend for good. At first the legs were shaped by hand. Later a machine did the bending in a hot press.

The result is a stool that is little more than a round top and three L shaped legs. It stacks, and a pile of them turns into a spiral. Many thousands were made, and many were used in the Viipuri Library, which was built and furnished between 1930 and 1935. From 1935 a four legged version could be ordered on special request.

the little sister of the architectural column

Alvar Aalto, on the L leg, quoted by Artek

The L leg went on to become a standard part in more than 50 Artek products. Artek says Stool 60 still takes more than 40 production steps, and the birch comes from central Finland, from trees 50 to 80 years old.

What it teaches a weekend woodworker

You can try the same idea on a scrap board. This is called kerf bending. Take a piece of softwood or birch, and near one end cut a row of thin, parallel slots with a fine saw, along the length of the board and stopping well short of the end. Bend it gently to see how far it will go. Then glue thin strips of veneer into the slots, clamp the piece around a form or a block at the angle you want, and leave it overnight. When you take the clamps off, the bend stays. Go slowly, wear safety glasses and keep your fingers away from the saw line.

Aalto's stool is only a round top and three legs. That makes it a good first build. Pick a simple stool plan, try one bent piece on scrap, and see what a single clever joint can do for you this weekend.