man applying glue on wood

Wood Glue: What Are Your Options?

Wood glues are essential to binding wood in applications like making furniture or repairing wooden items. Historically, different things were used to bond wood. Some glues have risen over time, being derivatives of the natural material of the 1940s to become the favorite adhesives of modern times.

Before you buy wood adhesive online, note that adhesives come in two major categories. Natural glues include vegetable, casein, soybean, and animal glues. Synthetic ones, on the other hand, are derived from coal, petroleum, and gas. The most common options available in the market today include:

Animal and vegetable glue

Also sometimes called “hot glue,” animal adhesives are made from cattle hide or sheep and horse bones. This kind of glue only works if applied while hot. It will bond with the wood and cool while losing moisture. During application, the hot adhesive will require the use of a brush. Animal glue will have a low resistance to humidity; the glue will weaken quickly if exposed to water or high moisture.

Meanwhile, vegetable glue is starch-based. It is made with starch that comes from rice, cassava, corn, and potatoes. One can apply this adhesive on wood as cold or hot. The glue still bonds with the wood while losing moisture. The process of curing vegetable glue is slow and can take up to 24 hours. Like animal glue, it will be loosened by humidity.

Casein and soybean glues

Casein adhesive is manufactured using buttermilk curd or milk mixed with a solvent. The adhesive is often sold as a powder that you combine with water to create a paste. The paste will bond based on evaporation. Casein has an average resistance to moisture, but one must be careful not to stain wood.

Soybean glue is often used alongside blood adhesives and is expensive compared to other glues. The paste is typically used with plywood and veneer. The two have a high moisture resistance.

Synthetic adhesives

worker using polymer glueTypically referred to as resins, these glues are polymers made to look like natural resins. They are created for specific woodworking applications. Synthetic adhesives have a strong resistance to moisture and form strong bonds with wood. They can either be thermosetting or thermoplastic. Thermosetting glues will include epoxy, phenol, melamine, urea-formaldehyde, and resorcinol.

Of all of them, urea is conventional, offering a moderate resistance to moisture and a relatively fast curing process even in high temperatures. Resorcinol and phenol glues are versatile and extremely durable. Melamine will often need to be used with other adhesives like urea to improve its resistance to moisture. Epoxy is perfect for small jobs.

Thermoplastic adhesives will include things like hot melts and polyvinyl acetates. Polyvinyl-based adhesives are conventional in the industry and will often be what people mean by “wood glue.” They have weak resistance to heat and moisture. Hot melts, on the other hand, are stable, and you apply them as beads or drops. They bond as they cool and have fast curing processes.

No glue is identical to another. In woodworking applications, the right choice of glue will affect the durability of the item. It is always wise to compare your options before choosing one.