How to repair a chair
Repairing furniture can be a rich learning experience for woodworkers. It’s a quick, hands-on way to learn how various pieces of furniture are built.
Eventually, the glue holding a chair together will lose its grip and you’ll start to hear squeaks from the wooden parts rubbing against each other. If the chair isn’t repaired at this point, gaps will start to open up in the joints and the chair will wobble. If a loose chair isn’t repaired, it can turn into a broken chair and that becomes a more challenging repair.
Colour: A Clue
When a joint works its way loose the first indication might be a different coloured gap between two pieces. This is the area that was hidden inside the joint when a finish was applied to the chair.
One-handed clamps have soft pads and can usually be reversed to spread a joint apart. Bennett likes this style of clamps for chair repair.
Once the legs and stretchers are labelled they can be removed from the seat.
Separate the Loose Joints
Separate all the parts unless there is a joint or two that still seem to be fixed solidly together. It’s usually best to leave those joints.
Clean Out the Mortises
Bennett uses a Forstner bit to remove glue from the mortises, but tries his best not to enlarge the holes as this would create loose joints when they’re put back together.
Clean the Tenons
Bennett often uses a file to clean the glue from tenons, though he recommends beginners use sandpaper as that approach is less likely to remove too much wood and cause a loose-fitting joint.
Coat the Walls
Rather than just squeezing a bunch of glue into a mortise, Bennett coats the inside of the mortise walls with glue. This takes advantage of the glue’s properties and creates a much stronger joint.
Tap, Tap, Tap
A rubber mallet will gently set the legs back into the chair seat.
Add Some Weight
Concrete blocks, or another heavy object you might have around the shop or house, will help the chair settle so the chair doesn’t rock when dry.
Repairing a chair with loose joints requires taking it apart, cleaning the old glue off from the joints, and using proper gluing and clamping techniques to put it back together. This is what I call “Level 1 Woodworking Repair.” By learning these fundamental furniture repair techniques you can move on to more complex repair and restoration work next time.
If you’re tempted to simply squeeze some glue into the loose joint and hope for the best, it’s not going to hold. I’ll show you how to repair a chair with loose joints so it will last for decades to come.
This chair has a bit of movement to it and you can see the joints are starting to come apart on the legs. The back of the chair is solid so that doesn’t need to be repaired. I start this work by laying padding down on my workbench to prevent scratching the chair and then turn it upside down on the padding.
Disassemble the chair
The first step is to label all the parts. I use masking tape to label the legs and stretchers; front left, front right, back left, etc. This allows me to reassemble the chair quickly during the glue-up and also helps remind me how to rotate the stretchers so the top is still the top when it’s reassembled. This ensures that not only the chair will go back together properly, but that any wear marks will be located in their original orientation.
Using pistol grip clamps that have reversible ends, I switch my clamps to spreader clamps. This allows me to gently separate the parts without damaging them. I start by lifting the legs out of the chair. The front legs on this style of chair typically come out first, followed by the back legs. With the legs removed, I then separate the stretchers.
If I encounter a joint that’s solid and won’t come apart, I leave it. If there’s a slight amount of play in the joint but it won’t come loose, I apply a few drops of household white vinegar into the joint and let it sit for five minutes. Vinegar breaks down wood glue and releases the joint. (It won’t work if someone previously attempted to repair the chair with polyurethane glue or epoxy.)
Clean the joints
With everything labelled and taken apart, I move on to preparing the joints for glue. There are different types of glue, each with its own advantages and disadvantages. Some you want to avoid. I recommend hide glue for antiques and PVA glue for newer furniture. You can learn about other types of glue on my “Fixing Furniture” YouTube channel.
PVA glue won’t stick to anything but wood, so you need to clean off the old glue and any finish that may be on the joints. To clean out the mortises, I use a Forstner drill bit. I run the drill in reverse to get to the bottom of the mortise without damaging it. Then I change it to the forward setting to clear out the old glue.
For the tenons, the safest way to clean off the old glue is with sandpaper. The key is to not change the shape of the tenon and make it loose. Once you’re experienced enough with this, you can use a file which is a faster way to clean off the glue, but it removes material quickly so you can cause damage if you’re not careful.
Apply the glue
Once all the mortise and tenons are clean, I then lay out the parts in the right order to prepare for the glue-up. If you’re new to this, you may want to rehearse assembling the chair as typical glue gives you only 15 minutes or so to assemble everything. You want to make sure everything fits the way you want it to and you know where each part goes. It’s also a good idea to practice clamping the chair as it’s not always easy. You may have to make some dedicated clamping blocks for your chair.
I apply glue with an artist brush. I want to make sure I apply glue to both surfaces that will touch and that I have 100% coverage on the mating surfaces – the sides of the tenons and the sides of the mortises. I also avoid using my fingers as the oils from my skin can contaminate the glue and may weaken it.
I use the end of the artist brush to apply glue to the inside of the mortises and use the brush end to apply glue to the tenons. A common failure I see in the furniture I repair is that the builder squirted glue into the mortise and inserted the tenon. That doesn’t make a strong joint as it doesn’t maximize use of the mating surfaces.
Clamp the chair
I use a rubber mallet to make sure the chair legs are solid in the mortises of the seat. Then I flip the chair upright on my workbench. To avoid having a wobbly chair, I work on a flat, level workbench. Ninety-nine per cent of the time, this prevents me from having to trim one of the chair legs after the glue has dried.
The next step is to add weight to the seat to settle the chair down so all four legs are touching the bench. After that, I add clamps to secure the stretchers.
I’m a fan of pistol-grip clamps because they’re so versatile for this type of work. Not only do they work as spreader clamps for disassembly, but they work well for gluing up chair legs that are slightly splayed on an angle. The rubber pads allow the clamps to work at different angles, unlike bar clamps.
By following these steps to repair your loose chairs, they will be strong for decades to come.