How to Remove Glue in Joints
Glue is not difficult to remove from a wooden joint with a chisel or a drill, but separating the joint so you can remove it can be considerably more challenging. Even if a joint is loose, you can break the wood if you try to force it apart. If you're lucky, however, and the carpenter who assembled the joint used polyvinyl acetate (PVA) glue, which most carpenters do, you may be able to soften it with water. It won't be so easy to loosen the joint, however, if it was assembled with polyurethane glue, which is waterproof.
Wrap a wet towel around a joint fastened with PVA glue and leave it for 24 to 48 hours. Check it frequently and re-moisten it if it dries out. After the water has had time to seep into the joint and soften the glue, wiggle the wood and gently pull the joint apart.
Drill holes into the joint with a 1/8-inch drill bit if the configuration doesn't allow you to wrap a towel around it. Arrange the piece of furniture so the holes are vertical and the openings are facing up, then squirt white vinegar into them with a syringe. Let the vinegar soak in and soften the glue, then gently pull the joint apart.
Follow the procedure in Step 2 to loosen a joint assembled with polyurethane glue, but fill the holes with acetone or lacquer thinner instead of vinegar. Refill the holes every hour or so until the joint loosens, then pull it apart.
Heat the joint with a heat gun as an alternative to using thinner or vinegar. The heat may soften the glue enough for you to separate it. Don't use heat if you have already drilled holes and filled them with acetone or lacquer thinner. Both are flammable and may catch fire.
Ream old glue from inside larger mortises with a sharp chisel once the joints are separated. You can also use the chisel to remove glue from the tenon, or male part of the joint, as well as from spindles and dowels.
Clean glue from inside mortises and dowel holes that are too small for a chisel with a drill and a bit with a diameter slightly smaller than that of the hole. Operate the drill at half speed and rub the bit around all sides of the hole.
Use a rotary tool with a cylindrical grinding accessory as an alternative to a drill to clean glue from inside dowel holes. Operate the tool at about half speed and use light pressure to avoid widening the hole. You can also clean glue off of tenons, dowels and spindles with a rotary tool.
Use 100-grit sandpaper to sand any glue off of tenons, dowels and spindles that you can't remove with a chisel or rotary tool.
- Wear a respirator whenever you work with acetone or lacquer thinner, and keep either chemical away from open flames.
- If the joint was assembled with epoxy resin glue, you may not be able to separate it. Epoxy glue is harder than wood, and it doesn't soften.
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