Chair repair (Sgian Dubh? Custard?)

[Setch]

I've been asked to repair some rather nice dining chairs, which were presented to the client's father on his retirement in the 1950's.

They're 50s reproductions, so probably not too valuable financially, but of enormous sentimental value. I am, in the words of the client "the only chap I'd trust with them".

I've been mostly teasing apart failed notice and tenons on the corner joints and stretchers, then regluing with titebond hide glue. This had been very successful, but I have one joint which demands a different approach.

This dowelled joint in the ornate back of the chair has separated, and I'm unsure how best to deal with it. I don't think I can get a decent glue joint without sepating it more, and that will strain, and risk compromising, several other joints. I could try using a tiny hole to introduce glue with a syringe, but I don't know how long the dowel is, so not sure where to drill so the glue goes where it's needed.

I've also pondered fitting a bit of mahogany veneer to the gap, and gluing this in, so I don't intruduce too much tension when I clamp up, but this still doesn't really address the need to get glue onto the dowel to get a decent joint.


Any advice greatly appreciated.

 

[mrpercysnodgrass]

If you think you may damage the crest rail and or the splat by removing it you can still re-glue successfully but you will need to buy some fish glue. Firstly get a hacksaw blade and carefully scrape away the old glue, working from the show wood to the dowel being very careful not to break out any of the show wood. Scrape the dowel as much as you can. When you have it as clean as you can get brush on or syringe hot water into the joint. Have a cloth ready to mop up any overspill. Then flood the joint with the fish glue and leave for a good five to ten minutes to allow the glue to soak in ( it will follow the hot water into the joint). Bang the rail back down. You may not need to clamp but if you do pay great attention to the joint on all sides to make sure the clamping pressure is not opening the joint on one side! Leave for at least one day for the glue to set.
Fish glue is quite expensive, you will not need much and may never use it again! If this is the case let me know and I can pop a little in the post for you if you decide to go down this route. Others on here may come up with suggestions that better suit your needs.

 

[Adam W.]

@mrpercysnodgrass Just wondering, is fish glue stronger than rabbit skin glue ?

 

[dzj]

50s? Could be PVA.

 

[Setch]

Thanks @mrpercysnodgrass for your advice and very kind offer. Echoing Adam, would fish glue work better than liquid hide glue, which I already have?

If it matters, I think the original glue was Casein. It's crystalline and brittle, but not as dark as I'd expect from hide, and it doesn't get sticky if you brush it with hot water. I glued one chair up with hide as a test case, and it seemed to stick well, so hopefully I haven't shat the bed by using liquid hide over old casein.

 

[Sgian Dubh]

I'm not quite sure why my handle was included in your thread title. I don't think I have superior insights into such repairs, although I used to do a lot of antique restoration and repairs a lifetime ago, but here goes anyway. I have done a few procedures (three or four) similar to that outlined by mrpercysnodgrass with some measure of success and once or twice not so successful. In the examples I've worked on the adhesive in the original assembly was hide glue, so the hot water flooding and introduction of new hide glue strategy made sense because of the new and old adhesive's compatibility. I can't see any reason not to follow the suggestion provided, although it may not be completely successful if the old glue is casein, PVA, or whatever.

However, a trick I have used in similar circumstances after doing something similar to what's already been suggested to close the gap is to bore a hole through the frame and through the tenon or, in your case, through the dowel, and glue in a cross dowel. Your cross dowel obviously needs to be smaller that the size of the existing dowel, so you might have to think almost as small as toothpick diameter, but you can make dowels of almost any size using a home made dowel plate. I've made dowels as small as 3 mm diameter with a dowel plate and a piece of straight grained hardwood, e.g., beech, oak, walnut, etc.

If you have to, and can, can reinforce the joint in this manner, you obviously have to disguise the cross dowel's presence, and doing so successfully depends on its location and your blemish repair skills. Sometimes such dowels can be inserted into unseen surfaces, e.g., the underside of a low stretcher, and at other times they're clearly visible without using a polisher's disguising arts. Slainte.

 

[Phil Pascoe]

If it matters, I think the original glue was Casein. It's crystalline and brittle ...

I never found casein glues very good in stressed joints such as those in chairs - it is as you say brittle. I repaired loads over years where the glue had just shattered.

 

[Setch]

I'm not quite sure why my handle was included in your thread title. I don't think I have superior insights into such repairs, although I used to do a lot of antique restoration and repairs a lifetime ago, but here goes anyway.

I found a few good posts by you on the subject of furniture when I googled for info, albeit from 10 plus years ago. Thanks for your thoughts. I should probably have included mrpercysnodgrass and Jacob as well, there's a wealth of knowledge here but my ability to call up the names on command is very poor.

I never found casein glues very good in stressed joints such as those in chairs - it is as you say brittle. I repaired loads over years where the glue had just shattered.

Yes, totally agree, although the counter arguement is that when joints fail, they shear at the glueline, so you can repair far more easily than if you snap off a tenon, or reduce a leg to splinters. This is a familiar idea from my ventures in guitar making.

 

[Adam W.]

Thanks @mrpercysnodgrass for your advice and very kind offer. Echoing Adam, would fish glue work better than liquid hide glue, which I already have?

If it matters, I think the original glue was Casein. It's crystalline and brittle, but not as dark as I'd expect from hide, and it doesn't get sticky if you brush it with hot water. I glued one chair up with hide as a test case, and it seemed to stick well, so hopefully I haven't shat the bed by using liquid hide over old casein.

Rabbit skin glue is quite light in colour and as it's the only animal glue I have experience of, I couldn't comment on the other types. Although Steve Latta mentioned in one of his veneering videos that liquid hide glue in a bottle took longer to set than other granular, opposed to pearlised, hide glues.

He also talked a little about glue strength, but I've no idea which is strongest.

 

[Setch]

The liquid hide glue has urea added to extend it's open time, and needs extended clamping and drying time - I've been leaving stuff 24 hrs to dry before stressing it, in clamps if practical.

Is the favour skin glue heated in a gluepot, or in a bottle ready to use?

Not directly relevant to this discussion, I'm just curious.

 

[mrpercysnodgrass]

I don’t know the technical make up of different glues so can only advise based on experience.
fish glue has very similar properties to Pearl/hide glue. It is not quite as strong but good enough for most joints. One of It’s real advantages is it is used cold and has a very long open time, it is also thin and will seep into gaps unlike scotch which will gel before it has a chance to do this even if it is thinned down.
The best way to re-glue your crest rail is to take it off, clean off the cascamite then re-glue with your hide glue. If that is not an option I think fish glue will work even though you will only get to a percentage of the joint. Although the chair will get picked up by the crest rail that joint will not get the stress that a joint on the leg/seat rail will get.

 

[Adam W.]

The liquid hide glue has urea added to extend it's open time, and needs extended clamping and drying time - I've been leaving stuff 24 hrs to dry before stressing it, in clamps if practical.

Is the favour skin glue heated in a gluepot, or in a bottle ready to use?

Not directly relevant to this discussion, I'm just curious.

I guess it's the Rabbit skin glue you're asking about.

I use it for gilding and it comes in granular form. For gilding, I mix it in 10 parts water and let it sit overnight, warm it up and it's ready for use. There is a filtering stage in between, but I don't think it's necessary for glueing stuff. Gilding is another matter and purity counts.

From what I gather from Steve Latta, is that granular hide glue is purer than processed and pearlised, and from experience it does make a clearer glue.

I don't know if it affects tack time or strength, but I'd like to find out.

I've got some parchment clippings for making glue as well, but I haven't used them yet and that's for the 14th century gilding rabbit hole that I'm in at the moment.

I see you're in town, I got it from Handovers in Stratford.