When it comes to woodworking or carpentry, wood glue is an incredibly necessary component. This type of adhesive is used to connect or fuse multiple sections of wood together. Whether you’re renovating a kitchen, building furniture, or performing other home improvements, you’ll find you rely on wood glue frequently throughout your projects.
Even though numerous methods exist for connecting wood pieces, like utilizing nails and screws, the most robust and durable bonds are produced by glue when applied correctly. The potent chemical bond arises from the glue penetrating the fibers of the wood, culminating in an indissoluble joint.
When working on your projects, it’s not necessary to use glue for every joint or assembling process. For example, glue is usually unnecessary for framing projects, but it’s essential to use it when constructing cabinets or furniture.
1. Polyvinyl Acetate Glue
Polyvinyl acetate (PVA) is the prevalent form of wood glue, and it has supplanted hide glue as the contemporary adhesive for wood.
Brands
Regarding PVA wood glues, Titebond, Elmer’s Glue, and Gorilla Glue are among the most frequently recognized names.
PVA wood glue offers various advantages.
- One of the biggest benefits is that PVA wood glue is the most popular wood glue around and is easy to purchase at most every large retail store, from Home Depot to Walmart.
- Some glues will change color with time, such as regular Elmer’s glue, which is a PVA glue but not intended for wood and generally a weaker solution, but some will use it for small projects. But PVA wood glue won’t yellow over time, and it will stay somewhat flexible, and this helps keep the sheer strength strong over time.
- The fumes are not foul or harmful, and the glue is only toxic if you ingest it. It is strongly suggested that you make sure not to ingest PVA glue.
- There has been little to no breakdown over the years with PVA wood glue, although if the glue-up is poor quality, it will still come apart.
Different Types of PVA
Various types of PVA glue are available, including water-resistant, dyed, and water-proof options. The selection of the appropriate type of PVA glue for a project depends on whether it is intended for interior or exterior use.
The other choice that helps my decision is cost. Most of the PVA glues are about the same. Although, the Titebond No-Run, No-Drip is good for interior work because it is thicker and dries fairly quickly. It was developed for miter work on trim etc. and is recommended by Titebond for end grain-to-end grain glue-ups.
Titebond Original is not recommended for outdoor projects as it lacks water resistance. It is best suited for indoor projects. Titebond II, on the other hand, is water-resistant and can be utilized to create items such as outdoor furniture and cutting boards that are likely to come into contact with water.
Titebond III boasts better resistance to water and can be employed for constructions that will be submerged in water or constantly exposed to it.
If you require additional time to adjust and position pieces after applying glue, selecting Titebond III is advisable because it provides two times the open time of Titebond II and Titebond Original.
Elmer’s white glue is also a well-liked, harmless PVA that can be cleaned with water, and forms a sturdy bond once fully set.
The sole disadvantage of using PVA is that it does not soak up stain like wood does. This means that if any excess glue is left on the surface of the wood, it will remain visible after staining unless it is wiped away or sanded down prior to the staining process.
For almost all woodworking projects, this glue variety is utilized. The principal factors to take into account are the cost and the setting in which your project would be located. Even though it may be more costly over time, numerous individuals use Titebond III for everything.
While PVA is a suitable adhesive for woodworking in general, it is important to take certain precautions when working on delicate wood projects to avoid discoloration or imperfection of the surface.
2. Polyurethane Glue
Proper usage of polyurethane glue can result in a highly powerful adhesive. Although it may require some acclimation, professionals such as Craig Thibodeau suggest its utilization.
The advantages of using Polyurethane Glue
- Polyurethane glue’s benefits are that it doesn’t have a high moisture content and doesn’t make the joint swell like some water-based glues. This is because polyurethane glue is not water-based, and wood pores don’t draw this type of glue in as much.
- An interesting aspect of polyurethane glue is that you can still glue finished pieces together instead of having to glue them together first and then finish them. This is because the bond doesn’t require an uptake into the wood pores and adheres the pieces together differently than other types of glue.
- Another unique feature of polyurethane glue is that the glue cures from a chemical reaction to moisture. This makes gluing wood with a high moisture content or oily wood easier to glue over a glue such as PVA, which would have difficulty bonding these types of surfaces at all.
To ensure adequate adhesion, it is recommended to leave polyurethane pieces clamped for 24 hours due to their lengthy curing time. Any excess can be removed using mineral spirits or a scraper and sandpaper.
3. Cyanoacrylate Glue
Although CA glue is commonly known as super glue, it has other uses beyond that.
Brands
One-part CA adhesives, which include brands like Super Glue and Krazy Glue, are numerous.
Benefits of Cyanoacrylate Glue
- The holding properties are good, but the sheer strength is not the best.
- These glues are great for gluing wedges to pieces and using them for clamping assistance; then, because the sheer strength is low, you can hit them with a mallet and pop them off when the adhesive has dried.
- This type of glue can be used for general-purpose gluing, but it is more expensive than PVA and other glues.
- This glue is great for crown molding, trim, and furniture repair because it is clear and can cure quickly.
- Use CA glue for inlays. Since there are different viscosity ranges for CA glue, you can use the Bob Smith Industries Super Thin with Insta-Cure+, and this goes throughout the powder or dust you are using and creates a great bond for the inlay and then treat with Insta-Cure+ to cure and create a solid inlay.
4. Animal or Hide Glue
The initial glue was hide glue which has continued to be extensively utilized in crafting bows, producing musical instruments, and traditional woodworking. Though it is also known as animal and rawhide glue, the term hide glue is frequently used. Creating hide glue is a relatively simple process, but synthetic options are also available.
In its conventional form, hide glue is available as dry flakes or pellets that are melted using double boilers and applied while still heated. The adhesive possesses attractive features that render it a favorite among craftsmen who create antique furniture or those who work on projects that may require dissembling in the future to carry out repairs.
If you warm a hide glue joint, it will become loose, allowing you to disassemble furniture for repairs. Hide glue has the added benefit of being stainable, which is not the case for most other wood adhesives. Additionally, it is non-toxic.
Brands
Titebond Hide Glue is a product that has a slight advantage over natural hide glue. Although natural hide glue has a higher degree of stickiness than synthetic, the synthetic version has a similar holding power and is easier to store.
5. Epoxy Glue
Another potent adhesive is epoxy glue, which is composed of two liquid parts that undergo a chemical reaction upon mixing.
Benefits of Epoxy
- Epoxy is waterproof and makes a good filler as well.
- The cure times for epoxy can vary greatly, but a general rule of thumb is that the longer it takes to cure, the stronger the bond is. This is an advantage that epoxy has over PVA glue.
- Epoxy is a good choice if your joint is off and needs a little filling; you can mix sawdust into the mixture for the wood texture.
Epoxy has a drawback where its adhesion can be affected by acid and moisture, making it challenging to glue certain types of wood. For instance, oak’s acidic nature may pose difficulties when using epoxy. Additionally, epoxy is more costly than PVA and hide glue.
6. CA Glue
The common names we use for it are Superglue or Crazy Glue, but these are trade names for Cyanoacrylate, also known as CA. It can bond almost anything, but it is unsuitable for large-scale adhesive projects. It is most effectively used for small mending jobs, such as repairing chipped or fractured wood.
CA glue dries up quickly and is available in liquid and gel form.
Before you start your woodworking project, it’s important to consider a few key factors when selecting wood glue. The material you’ll be gluing will determine the type of glue that’s best suited for the job. It’s not recommended to simply opt for the strongest adhesive available without considering the specific needs of your project.
Polyurethane, also known as Gorilla glue, is highly durable; however, it is not advisable to use it on completed or ultimate assembly tasks since it may create a mess on the final product. On the other hand, although epoxy is likewise strong, it is more suitable for repairing wide crevices or loose connections than precisely fitting ones.
When choosing an adhesive, it is crucial to consider the material you are joining. It is recommended to buy only the necessary amount of glue instead of purchasing it in bulk. Opting for smaller containers will ensure that the adhesive remains fresh. In case of any leftover adhesive, it is advisable to check the label for storage instructions. Certain adhesives, like hide glue, can be stored in a refrigerator to extend their shelf life.
Make sure to label your glue bottles with the opening date to keep track of their freshness. As time passes, the adhesive strength of glue decreases, so it is important to know when you first opened it to avoid using it when its holding power has significantly weakened.
Choosing the Right Wood Glue
Strength of the Glue
Before selecting an adhesive, it is crucial to consider the level of bonding strength that will be achieved once the glue has dried.
Certain adhesives possess a greater bonding strength than others. As previously stated, the appropriate adhesive generates a bond of such great strength that the wood or its fibers will give way before the bond weakens.
To achieve the desired level of joint strength, select an adhesive that has the ability to generate the strength you desire, as some wood glues are more powerful than others.
Water Resistance
You require water-resistant glue if your project is exposed to water, or it will disintegrate upon contact with water.
Cutting boards are frequently exposed to water, considering they are utilized for cutting meat, vegetables, and other foods with high water content. If the adhesive used to create them is not waterproof, it will eventually lose its adhesive strength and come apart.
Outdoor furniture is subject to exposure from rain, dew, and other elements that will cause it to become wet. Therefore, the adhesive utilized to produce such furniture should also be water-resistant.
It is not advisable to use hide glue for outdoor projects because it can be easily undone with steam.
Dry Time / Curing Time
This article discusses five distinct varieties of wood glue, each with varying drying and curing times.
The term “dry time” indicates the duration it takes for the adhesive to lose its moisture and acquire some grip or stability, allowing for removing clamps. On the other hand, “curing time” is the period it takes for the adhesive to reach its maximum bonding strength.
The open time, or dry time, affects the application of these adhesives. If you require time to adjust a joint after applying the adhesive, then CA is not recommended because it dries up too quickly.
After applying PVA, you will still have time to adjust the joint, carefully align the members, and adjust your clamps before it dries and sets.
Viscosity / Thickness
The glue’s thickness, density, or viscosity also determines the kind of projects it is suitable for. Regarding minor fixes such as tiny cracks or hairline splits in wood, CA or super glue is ideal since it effortlessly spreads and dries quickly.
The thickest option for filling large cracks is epoxies. Polyurethane, like Gorilla glue, is also thicker than PVA and expands during drying, so it needs stronger clamping force to avoid movement. EH
