Best Way to Fix a Broken Back

[cpsmusic]

Hi Folks,

I'm relatively new to woodwork and haven't done much repair work.

I've been asked to try and fix an antique chair with a broken back. The back of the chair attaches to the rest via two dovetails - the side has split off one of these. Unfortunately the piece that split off has gone missing. The job is for a family member and they said fix it as best you can. I was thinking that there are two ways to approach this:

1. Glue the back on, and fill the missing part, then sand, etc.

2. Carefully pare out a rectangular section of the wood and then glue a new block of wood in and then fill, etc.

I'm interested in what more experienced woodworkers would suggest for this.

Cheers,

Chris

[Evanism]

I've been asked to do a lot of restoration and repairs. I've not done antiques.

If its a real antique of value, then I'd imagine the advice would be very different. I do have a friend who works in a museum and her advice is simple: make it semi obvious, remove only what you absolutely must and make it reversible for future work. It's an art.

If this is just an old loved chair, then I've done heaps of this. It's good fun and people are absolutely thrilled when they get them back.

sharpest chisels: clean out the mortise and flatten the damaged area. Timber to very closely match. Make up a piece/s that are larger than the damaged area. Glue it all in, shape when dry. Remake the mortise and fit it all back together.

Stain, varnish, etc to match existing.

This last part is the tricky bit. A lot of the value of old stuff is the patina and bangs that accumulate over the lifetime. The new bit would not match this, unless you are brilliant, so I'd make it look new, make it look repaired. Make it very very good, but it might look better if it's slightly imperfect.

I'd resist working on anything other than the affected area. It's tempting to start sanding everywhere and refinish the whole job. I've often fought myself over this and only did it once on a table that was too far gone....but I made the old stuff stand out so the "grandpas axe" is obvious..

Perhaps some better/bigger/more photos and the forum can ID the timber, finish and how to color match?

[Thumbthumper]

Hi Chris,

I've fixed many chairs with similar problems.

It looks like Australian Red Cedar, but if the chair is English, it may be Mahogany. Aussie Cedar would be a good match in any case.

These chairs were never screwed or nailed. They were just glued into the sliding dovetails.

Chisel the damaged area flat, glue a new piece of similar timber in, then shape. I use a combination of chisels, planes and spokeshaves to do this. I don't like sanding as it is noticeable when you polish over the repair. You also need to shape the inside section of the dovetail with a chisel. These chairs get all of their strength from these joints.

I would recommend hide glue, but I know that's not practical for most people. You can use PVA, but make sure you clean it very well after gluing in the new piece with a damp rag.
The original finish would have been shellac. I would dip a rag in a shellac mix and rub it over the new piece several times. You may be able to disguise it with a bit of poly varnish that you have handy.

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The next step is to clean off all the old glue with a chisel. Both the female dovetail sections and the male sections on the back frame.

You can now apply some glue and tap the back onto the back frame.

Hope this makes sense.

Cheers,
Stu

EDIT : A closer look at your photo tells me it is definitely Aussie Cedar. Let me know if you have any problems getting hold of a scrap piece to glue in. I can send you some at the cost of postage.

[cpsmusic]

Thanks for the quick replies.

Yes, I'd say the wood is red cedar and that the chair is most likely Aussie. The chair belongs to my sister who wants it "fixed" and just wants me to get on with doing it!

I have some hide glue and a glue pot so that's no problem.

The part I'm really not clear about is how to remake the dovetail slot (not sure if that's what it's called). Is that done before the new repair piece is shaped or after? This seems to be the hardest part as the slot will need to fit the pin (?) fairly accurately.

[Thumbthumper]

Thanks for the quick replies.

Yes, I'd say the wood is red cedar and that the chair is most likely Aussie. The chair belongs to my sister who wants it "fixed" and just wants me to get on with doing it!

I have some hide glue and a glue pot so that's no problem.

The part I'm really not clear about is how to remake the dovetail slot (not sure if that's what it's called). Is that done before the new repair piece is shaped or after? This seems to be the hardest part as the slot will need to fit the pin (?) fairly accurately.


Shape the slot after you glue on the piece. Make sure the piece you glue on overhangs just a bit. Make sure the glue is completely dry. Shape it with a chisel bit by bit. Keep checking with the back of the seat.