The Wassily chair was invented in the 1920s by Marcel Breuer, a renowned architect. This iconic lounge chair was named for the artist Wassily, a contemporary of Breuer's. The design is one of the earliest examples of the modern style, and has a seamless tubular design based on a bicycle. Authentic Wassilys are now selling for more than £1,300 (as of 2010). Since the Knoll Furniture Company began producing them in 1968, they have had a serial number and Marcel Breuer's signature stamped onto the base. Earlier versions were made between 1927 and 1968, but don't have any identifying stamps. The key is the design and dimensions--31 inches wide, 27 1/2 inches deep and 29 inches high. If you are considering replacing any of the leather on a Wassily, keep in mind that you might be compromising the authenticity of the piece.
Measure the width of the straps to be replaced and purchase leather similar to what is currently on the chair. The leather on Wassily chairs is typically cowhide or Spinnebeck brand belting leather, and can be either smooth or covered with hair. Some versions use Cordura brand nylon strapping.
Remove the screws or bolts from the chair to disassemble it. Slide off the leather piece to be replaced.
Use the old leather strap as a measurement and cut the new leather strapping material to size. Keep in mind that leather stretches as it is used, so cut for a snug fit.
Sew seams on each end of the strap to create openings for the tubular frame to fit through. Wrap the strap around the frame before you sew to get the proper fit.
Slide the new strap back onto the tubular frame and reassemble the chair.
If your chair is a true Wassily, you might want to consider using a Knoll-recommended leather specialist to repair your chair.