Alfredo Zertuche’s SLW Chair came onto our radar and we found the unique angles and beautiful craftsmanship worth investigating further. The chair came about after studying old Danish carpentry and furniture design and he decided to focus on three main characteristics: a low profile, design and materials selection, and the fabrication process and techniques. To complete the solid wood chair, Zertuche used traditional Mexican saddlery methods to construct the seat and backrest, sewing the thick leather by hand and strapping it to the frame. Let’s go back and see how this chair was created in this edition of Deconstruction.
The design came from studying postures combined with structural solutions to generate a geometry that would respond to it. When I started working with triangles, I understood that the structural capabilities of the shape would depend on how to combine them… how the joint would work.
By studying some profiles, I discovered that the relationship between the line of the joint and the vertical load was the key point to this. By reducing the angle between both of them, the joint would gain strength, because the weight is pushing down, instead of “peeling” the joint.
So I built a few plywood mockups, to test the angles, dimensions, lengths, and heights of the seats and backrests. This gave me the opportunity to test different ideas fairly quickly and make the necessary changes to it.
Once I was satisfied with one of the mockups, I started to figure out how much material I needed and how to properly use most of it, I started to build some boards, from which I was going to cutout my triangles. This was the moment when we picked the grain alignment.
Each wood board was patiently planned, perfectly squared to make sure that the final board was one smooth, leveled surface.
Then the boards were clamped for 24 hours to allow them to fully dry.
After the boards were fully dried, the triangles are cut from it. What is important is the direction of the grain and how it behaves with the joint. The triangles were aligned to be cut that way so the grain would meet perpendicularly and avoid peeling between the surfaces.
All triangles fit together perfectly, they are ready to be glued. More than 30 clamps are used to hold together four joints.
After 24 hour of drying, two different sets of holes are drilled on the interior faces of the profiles. First, the holes for the mortise and tenon, and later the pockets for the horizontal supports are milled.
Then, the profiles are sanded and using a router, the edges get rounded, with the consistent 1/2’ radius used on previous perforations.
After sanding, the chair is placed together for the first time. The leather seats are tested and everything fits right in place.
Most details are sanded by hand, like the holes for the straps, to avoid the sharp edges that could mark or cut the leather.
More than ten coats of tung oil were applied to the chair. Every day a new coat of oil would be applied to be sanded the next day. Day after day until it became a hard surface.
At the end there is this low lounge chair, where two old craft traditions from worlds apart come together into a comfortable, strong and lifelong chair.
Once the original SLW chair was complete, Zertuche began a series of 25 with different seat and backrest options.
The chair was fabricated with the advice of Peter MacKeith at the Architecture Shop of Washington University in St Louis in 2014, when Zertuche was doing his Masters in Architecture program.