The wood glue you use can make or break your project, but with so many options out there, how exactly do you choose one? Here is your simple and handy guide to wood glue:
Polyurethane glue is an expanding wood glue. When applied, it can grow up to three times its starting volume and fill uneven joints or surfaces. This may be a disadvantage for some since if it is over-applied, the glue produces a large amount of squeeze out that needs to be cleaned out.
However, excess glue can be easily wiped off with a solvent like acetone or lacquer thinner while still not dry. When it hardens, you can chisel it off or sand. Polyurethane glue is also highly water-resistant, making it the primary choice for outdoor projects.
PVA, or polyvinyl acetate glue, is the most popular type of wood glue. It is also sometimes referred to as yellow glue or carpenter’s glue. It is water-based. When applied, its water content diffuses into the wood or evaporates completely, leaving a flexible film required in many projects involving wood.
The flexibility of PVA, however, makes it unsuited for projects that require structural or load-bearing integrity. Some manufacturers tweaked the formula of their glues to enhance certain attributes depending on the woodworker’s needs like water resistance, initial tack or stickiness, and the time it would take before it dries.
Epoxy glue is made up of two agents — a resin and a hardener — that, when mixed, creates a very strong polymer. It becomes very solid that it can fill gaps and voids in and between wood parts. It is also highly water-resistant. Some variants perform well even underwater. That is why they are the prefered glue of many boat builders.
However, epoxy has several downsides. First is the cost since this type of glue can be expensive. Second, it is more complicated to use. You have to mix it well with an accurate ratio. Otherwise, your epoxy would not cure properly and leave you with a sticky mess. Lastly, exposure to hardeners and uncured epoxy can cause contact dermatitis or allergic reactions.
As epoxy generates heat when it cures, it can be a burn and fire hazard under certain conditions. To avoid accidents, work with small batches and use a container that will allow heat to dissipate. Reminder: Epoxy will burn small plastic cups so don’t use those and find a better container.
Hide glue, as its name suggests, comes from animal hides. It is more often used to repair antique or musical instruments, although it can be used in a variety of other projects. This type of glue can be heated and applied to a piece of wood with a brush. However, there is also a variant that already comes in liquid form and in a bottle container, ready to be used.
It is non-toxic and, once cooled, can be stored and then reheated to be used again. Moreover, hide glue has a unique reversibility trait. It loses its grip when any kind of heat is applied, which allows heirloom pieces to be repaired and restored over and over again throughout the years.
When buying and using wood glue, read carefully and follow the instructions provided. If this is your first time working with any type of wood glue, it is best to buy small quantities. However, if you find yourself with excess wood glue, make sure to store them in a cool dry place.