It is crucial to select the appropriate wood glue for your woodworking project. However, what is the ideal wood glue for you and what differentiates each type? Continue reading to gain more insight and understand the various types of wood glue and their respective uses.
1. Polyvinyl acetate glue
If you have yellow or white wood glue at home, it is highly likely that you have polyvinyl acetate (or PVA glue), which is the most commonly used type of wood glue.
PVA glue is favored for its affordability, adaptability to both indoor and outdoor projects, simple cleanup, and strong bond. Once dried, it forms a bond that surpasses the strength of the wood and exhibits exceptional shear strength.
PVA glue, being water-based and water-soluble, enables easy cleanup. You can use a wood glue brush, finger, or wood glue dispenser to apply the glue to your project, and then wipe away any residue swiftly with a damp rag.
Given their popularity, it comes as no wonder that there are numerous choices of PVA glues available, such as Titebond Original, Titebond 2 Premium, Titebond 3 Ultimate, and Gorilla Wood Glue. Among these options, all of them are resistant to water, except for Titebond Original. Meanwhile, Titebond 3 Ultimate stands out as the sole glue rated as waterproof.
PVA glues have assembly times that vary from 10 to 15 minutes for certain Titebond products, while others can take as long as 20 to 30 minutes. All of them, however, require a full 24 hours to completely cure and are most effective when applied in temperatures ranging from at least 50 to 55 degrees Fahrenheit. The bonding strength of these glues ranges from 3,600 to 4,000 PSI.
Certain PVA glues have received FDA approval for indirect food contact, making them suitable for use with cutting boards in a safe manner.
2. Polyurethane glue
Polyurethane, a synthetic plastic resin, possesses water-resistant and waterproof properties. Its bond is triggered by the presence of moisture in the air, making it highly effective in humid surroundings. Its versatility extends to numerous other applications.
Polyurethane glue outperforms PVA glues in specific situations. It is particularly effective at bonding end grain to end grain and is ideal for use with oily woods. The inability of water-based wood glues, such as PVA, to bond oily woods is due to the fact that water and oil do not mix. In contrast, polyurethane glues excel in this aspect.
Polyurethane glues, unlike water-based glues, do not cause wood to swell, which is similarly applicable to joinery requiring precise measurements.
Polyurethane glues have the distinctive characteristic of providing a lengthy period of up to 30 minutes for assembly, in addition to a brief clamping time. Unlike PVA glues, polyurethane glues are the superior choice for bonding finished wood.
The disadvantage of using polyurethane glues is that they are more toxic and expensive compared to other types of wood glue. Additionally, they can be harder to clean up, but this is not impossible. You can remove excess glue by applying acetone with a rag, or if it has dried, you can use a chisel or sandpaper.
3. Cyanoacrylate glue
Cyanoacrylate (or CA glue), also known as super glue or Krazy Glue, is a fast-drying acrylic resin that creates a strong and inflexible bond. Compared to other wood glues, CA glues offer several benefits to hobbyists.
First, CA glues cure quickly. On the longer side, they cure within a few minutes. By using accelerator sprays alongside a small amount of CA glue, an immediate cure can be achieved. Simply spray the section of your workpiece that does not have CA glue, then firmly press the two wooden blocks together to create an instant bond.
CA glues have the characteristic of being transparent when they are dried. They are available in different viscosities, ranging from very thin like water to very thick like gels. Additionally, these glues do not require clamps in order to create a strong bond. However, it is not recommended to use CA glue for crucial woodworking joints or in situations where shear strength is of utmost importance. As a demonstration, if you were to strike your woodworking piece with a mallet, most CA glue bonds would easily break.
The properties of CA glues make them the ideal choice for temporarily bonding woods. An example of their common use is aiding in the clamping of angled joints, typically done with traditional wood glues. By using CA glue to attach two wooden blocks to your workpiece, you can create a temporary bond that allows your clamps to hold on, which would otherwise be impossible.
4. Epoxy
Epoxy is a polymer known for its exceptional tensile strength, which can range from at least 5,000 PSI to over 10,000 PSI. It is typically available in two components that need to be mixed together for activation.
The cure times of epoxy vary greatly, while still maintaining its waterproof characteristic. JB WoodWeld Epoxy, a type of epoxy commonly used in woodworking, sets within 6 minutes and fully cures in a span of one to three hours. On the other hand, some other types of epoxies may require several days to reach complete curing.
Epoxies are frequently applied in woodworking to fill cracks and voids, mainly due to their wood glue properties. In case of a misaligned joint, a mixture of sawdust and epoxy can be used to fill any gaps. Although other wood glues can be used for the same purpose, it is worth noting that epoxies have superior finishing qualities and seamlessly integrate with the finalized wood.
One drawback of epoxies is their high cost. Additionally, they are not compatible with acidic woods or wood blocks that still contain moisture.
5. Hide glue
Hide glue is derived from the connective tissues of animals’ hides, possessing a strong adhesion strength of up to 5,000 PSI; however, it is typically found within the range of 3,000 PSI.
Hide glues possess unique characteristics that differentiate them from other types of glues. Firstly, they are free from VOCs. Additionally, hide glues can be heated, allowing for the bond between two pieces of wood to be softened and subsequently separated. In contrast, PVA glues, polyurethane glues, and epoxies lack this capability.
Hide glues have lost popularity in comparison to PVA glues due to several downsides. These downsides include the requirement of heating for application, lack of waterproofness, a short shelf life of one year, and difficulty in finding them. However, Titebond Hide Glue remains one of the few hide glues that can still be purchased.
The best wood glue to buy
Everbuild 502 all purpose wood glue
Everbuild 502 is gaining popularity in the UK as one of the most commonly used wood glues. Its versatility is notable, as it effectively functions as both a waterproof glue suitable for various exterior and interior projects, and a white glue that is resin-based. As a result of its resin content, it is capable of penetrating deep into the wood grain, thereby providing a robust and long-lasting bond.
Using this wood glue to clean up is very simple – all you need is a damp paper towel. Additionally, it dries fast, with a working time of 5 minutes. While it does require 24 hours to fully cure, you can resume your project in approximately an hour. This PVA glue is essential for any DIY or woodworking project.
Mitrebond industrial superglue and activator
If you have had some experience in woodworking, you are likely aware of the usefulness of having superglue in your toolkit. Whether you need a temporary or long-lasting bond, superglue can be incredibly helpful.
Mitrebond, known for producing top-quality super glue in the UK, offers this particular product with an activator that accelerates its setting time to just a few seconds. Suitable for a wide range of uses, this super glue is highly versatile and can be applied in various DIY or woodworking projects, as well as during the restoration of sash windows. It holds equivalent value to the previously mentioned PVA glue.
Gorilla glue
Gorilla wood glue, known for its exceptional strength, is highly regarded by woodworkers who rely solely on its reliability. This PVA glue forms a durable bond for various wood joints within a timeframe of 20-30 minutes, influenced by the ambient temperature, ensuring an enduring connection.
Gorilla wood glue can be used both indoors and outdoors and it dries without leaving any visible residue. If you have any upcoming outdoor projects, this glue will be very useful to you. It is very convenient to use as it spreads and cleans up easily. Additionally, it is compatible with almost all types of wood available in the market, making it a valuable addition to your tool kit.
What to consider when choosing the best wood glue
When selecting the appropriate wood glue for your project, there are numerous factors to consider such as the specific project requirements, desired durability, the type of wood utilized, whether it will be employed indoors or outdoors, the time it takes to cure and dry, and many other aspects.
Adhesive strength
The strength of adhesives for wood differs. If you need to temporarily or permanently bond two pieces of wood, there are suitable glues available for both purposes.
Viscosity
There are various viscosities of glue, such as CA and epoxy, that can be found in the market. You have the option to select a thin adhesive if you want to reach and fill cracks or a thicker adhesive that will not penetrate deeply into the wood, based on your requirements.
Shelf life and storage
Certain glues, such as crystalized hiding glue, have the ability to be stored for an extensive period of time. On the other hand, some PVAs have a shelf-life of approximately six months. Epoxies and CA glue, if unopened, can be stored for extended durations.
Glue manufacturers usually indicate the storage duration on the bottle, however, extreme temperatures can impact glue effectiveness. When a glue exceeds its shelf-life, its adhesive strength decreases. Therefore, it is advisable to purchase smaller quantities of glue to avoid unnecessary wastage.
Drying time
CA glue dries rapidly, whereas PVA and epoxy glues require 24 hours to cure and up to a week to fully cure. Despite its fast drying time, CA glue may not be suitable for every woodworking project. In certain cases, the use of slower curing glues is necessary to ensure the optimal strength of joints.
Tips for using wood glue safely
Wear eye protection
Have you ever experienced having super glue in your eye? If not, let me tell you, it is really unpleasant. The reason is that super glue does not dry when it comes into contact with your eye; instead, it remains on the surface of the water in your eye.
When you close your eye, it becomes sealed shut, therefore if you accidentally get super glue in your eye, you should ensure that it remains open and cleanse your eyes thoroughly. It is advisable to apply eye protection before handling any super glue, as you will greatly appreciate it later on.
Practice the glue up
Rather than being a safety tip, this is advice from a hobby woodworker based on personal experience. It is highly recommended to undertake a dry run of a complex glue-up before applying any adhesive. This practice allows for proper placement of clamps, correct alignment of screws, and identification of potential issues that may arise during the glue-up process. By doing this dry run, there is no need to rush before the glue starts to set.
After you have gathered your clamps, screws, and prepared your mind, proceed to apply the glue and ensure that everything is firmly glued together.
