This will be a topic that I will try to keep simple and concise. As a repair professional I see how the majority of people try to repair their own furniture. The first subject I would like to look at is glue.
First off, the glues we use in woodworking are stronger than wood, for the most part. That cam be a great asset! That means if you repair a break, it won’t break there again. For the most part that is true. It really would depend on the situation along with several variables, though. I would like to offer some reasons why just putting glue on that loose piece of furniture is not a lasting repair. Wood glue is thought to be the answer for gluing wood, after all, it is wood glue. What isn’t spelled out is the correct way to use it. Nor what not to use it for. Wood glue has to have a clean and tight joint, free of voids. It does not fill voids and retain it’s strength. or does it stick to other glues, or itself, if used previously and is dry. That means you can’t just pull that leg out of your chair, stick wood glue in the hole, shove it back in and expect a long lasting repair. There is old glue in the hole that it won’t stick to. If you attempt to remove the old glue, do so carefully so as to not create voids that will weaken the glue joint. Now wood glue will fill some voids, but it’s maximum strength requires two mating surfaces clamped together. Wood glue is great for a split that can be clamped back together before time passes and splinters become missing. You also don’t want the break to collect dirt.
I use wood glue when the need arises, but I prefer hot hide glue. Yes, it’s made from animal hides. It’s been found on artifacts that date back in Bible times. Seeing as the Romans used it, I wonder if Jesus used this glue? In fact, furniture from ancient Egypt has veneer held on with hide glue to this day. The Chinese used it too. Most of the antique (actually 100+ years old) furniture was built with hide glue. Hide glue is more susceptible to moisture and humidity changes, but that is actually one of it’s strengths. Hide glue is reversible! That means I can reglue a joint I glued crooked. A heat gun and patience will allow you to undo your mistake. It also sticks to itself, meaning you can reglue old joints without all the work of trying to clean off the old glue, if it was previously glued with hide glue. Clamping is necessary for most woodworking projects, but hide glue will set up quick enough to allow the use of rub blocks. Hammer veneering doesn’t require clamping either, allowing you to apply veneer without claps or culls. You can easily fix a bubble in your veneer using an iron to heat up the glue to allow it to tack again. Hide glue is mostly protein instead of chemicals, which allows it to be used as fertilizer after it starts to go bad. It does have a shelf life. You’ll know when you see mold on top of your glue that it’s past time to clean the pot and make a new batch. Old Brown Glue is a great way to start using hide glue without all the heating equipment for hot hide glue. It comes in a bottle you can keep in the fridge to extend shelf life. I will cut this short here. I highly recommend you read the Hide Glue book by Stephen Shepard for more information on hide glue.
Now let’s touch on nails;
They have their place in furniture, but should not be used in the joinery of the furniture. The joinery is supposed to be held by glue. I think the misconception comes from the idea that carpenters nail everything. That is mostly true but the nail is taking the place of the joint, in most cases. You can’t glue the end of a 2×4 against the side of another and expect that to stay. That is not a form of joinery that has any strength, so nails are used. I want to point out one more thing about the carpentry thought. When a nail has to be pulled, is it easily done without harm to the wood around it? No, and that is the problem with nails being used to fix furniture. The nail(s) may help for a short time, but then I usually get the job of trying to pull apart the joinery and the tiny brad nails are splitting the pieces. Unfortunately most of the modern chairs from overseas have these brad nails in every joint already, along with glue starved joints. So save yourself money and leave the nails out of your furniture joints.
On to screws: