Here are tips on repairing old chairs and warped wood surfaces.
Unsteady chairs are typically caused by loosening of rungs. (1) Take out loose rungs, get rid of all the glue from both rung and hole, put on new glue, bind firmly using a cord till glue has set. (2) Metal "rung fasteners" are available to slip over a rung that is quite narrow. (3) Where multiple legs are to be repaired, use "chair-bracing sets" to hold the legs taut throughout the drying period. When shakiness is made by loose slat, apply corner splines.
Sagging chair cane
To tighten caning,
Substitute warped tops. To gain stability, use a glued-up board rather than a solid one. For example, if an 18-by-36-inch top is needed, glue up a top of three 6-inch pieces, or rip an 18-inch piece into three 6-inch pieces and then re-glue.
Minor defects in
Use stick shellac to mend minor defects in veneered surfaces.
Small defective areas in veneer
If damage is limited to a small area, repair it like so: (1) Select a patch slightly bigger than the damaged part. Apply three or four small spots of glue to the damaged portion, press the patch over the glue and let it set. (2) Using a sharp knife held vertically, cut through both patch and damaged veneer. This cut does not have to follow a rectangle; it is better to taper it to a point. (3) Detach the patch-and clear out the damaged veneer inside the cut area. Apply glue, insert the patch, and place a weight on it. Take away excess glue from the surface and let the repair set.
Extensive damage in veneer
If the damaged area is too wide for repair by these methods, re-cover the whole surface.