First, remove the old spline and cane from the groove. Loosen the spline, bit by bit, with an awl, being careful not to scratch the wood surface of the chair. A little diluted vinegar can help soften the old glue. Clean the groove to get it ready for the replacement seat. If you have used vinegar let it dry before putting in the new seat – otherwise the vinegar will work against the glue you apply.
The piece of replacement sheet caning needs to be 2″ larger (on all four sides) than the area to be caned. The extra material becomes the selvedge that sits in the groove. Before using, soak the piece of sheet caning in hot water for an hour.

The water softens it slightly and makes it easier to wedge into the groove.
Notice that the sheet caning has a shiny side and a dull side. The shiny side is the side you want to be right side up on your chair. Lay the sheet over the groove and align the pattern with the chair so that it is symmetrical.

Gently pound a wedge into the middle of the groove on all four sides. Begin with the back rail, then do the front, and finish by doing the two sides. Then, in turn, take each wedge and tap the cane in, widening the area you are compressing.
Eventually the entire groove will be filled in. Go around once more, tapping the cane into the groove with the wedge to make sure it is in place. The cane may not seem to be very tight, but it will tighten more as it dries.

Cut off the excess sheet caning with an ‘X-acto’ type knife. Cut just below the top inside edge of the groove, and cut towards the outside edge of the chair.
Apply a bead of wood glue in the groove.

This is a good time to put the spline into some water. It only needs to soak for 5 minutes for our purpose. Don’t leave it soaking for too long, because over-soaking it will cause it to swell.

The final step is to pound the spline into the groove. Start at the middle back of the chair. The spline is wedge shaped, so make sure that the thin side of the wedge goes into the groove. Do not pound directly on the spline with the hammer. Instead, use your wedge laid on its side. That will buffer the pounding so that the spline is not marked by the hammer. If your chair is curved, bend the spline to help it fit the curve. If your seat is more square shaped, then you may need to pre-cut the spline with 45º angles.

Let the cane dry overnight. Don’t worry if the seat is not stretched tight as it will tighten as it dries.
The cane does not need a finish because it already has a natural protective gloss. However, for effect, you could apply wood stain to darken the cane and spline.

Tools Needed

Awl, hammer, wood glue, 4 wedges, x-acto knife, sheet caning and spline.