Bonet BKF® - Butterfly chair

Who designed the Bonet BKF®?

Antoni Bonet, Juan Kurchan, and Jorge Ferrari-Hardoy designed the BKF in 1938, while working together as Grupo Austral. The chair took their initials, and its winged leather shape soon earned it a second name in English: the Butterfly Chair.

Why is the Isist Atelier edition different?

Isist Atelier is the only maker in the world authorised by the Bonet family to reproduce the BKF, which it sells as the Bonet BKF®. The licence ties the chair to the original proportions and details. According to Isist Atelier, this edition is part of the permanent collections of MoMA in New York and the Museu del Disseny de Barcelona.

How is the Bonet BKF® made?

The frame is 12 mm solid steel rod, assembled mechanically, polished by hand, and finished in black epoxy. The feet are capped with fire-retardant rubber hose, which protects floors. The leather slings are 100% vegetable-tanned and made by hand in Isist Atelier's Barcelona workshop. The canvas slings are 100% cotton.

What is vegetable-tanned leather?

Vegetable-tanned leather is tanned with natural tannins from tree bark and wood, such as chestnut, mimosa, or quebracho, rather than with the chromium salts used for most leather today. The process takes weeks rather than a day or two, and gives a dense, full-bodied leather with a warm, woody smell. It feels firm when new and softens as it is used. Isist Atelier uses 100% vegetable-tanned leather for the leather sling of the Bonet BKF®.

How will the leather change over time?

Vegetable-tanned leather darkens and takes on a patina with light, touch, and use. Natural leather changes the most, moving from a pale tan towards a deeper honey colour; darker leathers change more subtly. On the Bonet BKF®, the seat and the edges of the sling will darken first. Small marks, creases, and variations in tone come from the hide itself and are not defects, and no two pieces age in quite the same way.

How do you care for vegetable-tanned leather?

Dust it with a soft, dry cloth. If it gets wet, blot it straight away and let it dry naturally, away from radiators and other direct heat. Every few months, or whenever it looks dry, apply a little colourless balm or cream made for vegetable-tanned leather, testing it first on a hidden spot. Avoid solvents and household cleaners. Leather is not waterproof, so keep the chair out of the rain, and out of strong direct sun if you want natural leather to darken evenly.