Wood glue has been used since ancient times. Nails and screws are good but in some cases you don’t want to use them, then glue is the only solution. The combination of glue and nails or screws is often used when you want a joint firmly in place. Here is an overview of the most common glues for woodworking.
Animal glue was used in woodworking already in the ancient Egypt. In the ancient Greece and Rome, animal glue was used in veneering and marquetry. Today, you are not restricted to just animal glue, you have a lot of different kinds of glue to choose from. Most of them are much more efficient than animal glue.
The main glue for woodworking is the yellow glue also known as carpenter’s wood glue. It is also sometimes called PVA glue, which stands for Polyvinyl Acetate. But some people make difference between white glue which is genuine PVA and yellow glue which, strictly speaking, is aliphatic resin emulsion adhesive. Just to complicate things, it looks like some producers dye their white glue yellow. So you need to read the labels. You have a lot of brands to choose from. Note that not all of them are waterproof, that is another reason for reading the labels carefully. Another thing to be aware of is that yellow glue has a fairly short shelf life so check the expiration date before you buy.
The yellow glue has a number of advantages. You have a couple of minutes during which you can adjust the pieces without decreasing the strength of the glue. The yellow glue requires clamping. Excess glue can be wiped off using a damp rag or you can sand it off once it has dried. One drawback with yellow glue is that nothing really sticks well to the hardened glue. This makes repairs complicated.
White and yellow glue have similar characteristics, they have about the same strength. The main difference is that white glue dries slower. So if you have something that takes more than 10 minutes to assemble, you may prefer to use white glue rather than yellow glue.
As mentioned earlier, animal glues have been used in woodworking for centuries. Hide glue is still being today used but it is not as popular as many of the modern glues. Hide glue is more difficult to use than white and yellow glue, it is messy. It can be removed with water so it is not suitable for wet conditions.
Cyanoacrylate glue, more popularly known as crazy glue or super glue, is often used for smaller repairs. It is not just a wood glue, it can be used for most materials. The advantage is works very quickly and it is fairly strong. So be careful not to get any glue on your fingers.
Some woodworkers love Gorilla Glue, which is a polyurethane glue. It is very strong and it is waterproof. But it has one drawback, it swells as it dries. It is also very difficult to remove if you get it on your skin.
Epoxy can be used for a lot of materials. Epoxy glue is made of two parts, a resin and a hardener. When the two are mixed together, the chemical reaction creates a strong adhesive bond. The main advantage of epoxy is that it works very well in most conditions. This makes it very popular for outdoor use. Note when using epoxy glue, you are not supposed to clamp the pieces together. Using too much pressure can weaken the glue.