I really dislike repairing and refinishing old furniture but I sometimes get hooked into it. Most "old" furniture is just factory made stuff, and "old" usually means early 20th century.
Anyway, this is six walnut dining room chairs. I wish I had taken "before" pictures but I didn't think of it. Several of the chairs needed repair - one had a loose joint from the seat into the back rail, another had some splitting of the back rail that, while sound, would have caught on the user's clothes, two had places where the wood was damaged and needed a replacement insert, two had loose crest rails, probably from the chair falling over backwards, and the back splat on one was split from top to bottom.
In quality, they were good and bad. Well constructed, actually, with traditional mortise and tenon from the seat into the back rail. Many chairs from this era used dowels and dowel joints usually do not last. Only one joint was loose and it was because the back rail had split at the joint.
The wood is walnut but the selection is very poor. The pieces are cut from glued up stock, with light sapwood glued to dark heartwood so you can easily see the joints. The crest rails were each very light which made finishing to a consistent color difficult.
The wood had also been infested with woodworms at one time. As I sanded the chairs to remove the old finish, the woodworm larvae channels were exposed. There was no active infestation, however. I used wood filler to fill all the visible woodworm channels. You can see the filler in the second picture. And just a side note, woodworms generally only eat sapwood, not heartwood.
The process was to do all the repairs first, then sand the wood to remove the old finish. I did not remove the finish from the carved portions because I would have removed detail in the carving. I just finished over the existing finish.
To get the final color, I used a mixture of commercial stains, with extra staining required on the crest rails to get them to match the rest of the chair. The finish was one coat of dewaxed shellac followed by two coats of lacquer.
Originally, the seats were coil springs and the seat area was barely higher than the seat rails. I chose to use an applied seat built on 3/8" plywood cut to fit the chair - and each chair was different so each plywood seat has to be matched to its chair - I numbered them to keep track. The applied seat added to the height of the chairs so I had to cut a bit off the legs to bring the seating height to normal. I cut 3/4" off the front legs and 1.5" off the back legs to give the seat backs a bit of an angle - I felt the original seat backs were too upright.
Anyway, that's the story. Took about a week to do all six. They should give good service for many more years.