Most woodworking projects will require glue at some point in the process. But what is with all the different types of wood glue and how are you supposed to know which one to choose? This article aims to answer those questions. You will find in-depth information on each of the 5 different types of wood glue, what types of projects each type is best for, and some tips on using them.
While polyurethanes have been around since the 30’s, they did not appear in wood applications until the 70’s. Polyurethane glue bonds well to wood and a wide variety of other materials including plastic, metal, laminates, and fabrics.
When polyurethane glue comes into contact with water it becomes activated, swells, and then dries and hardens. Once dry, it is very hard and waterproof. However, this glue can be messy to deal with and hard to remove. Polyurethane glue will stick to nearly everything, stain your hands, and requires a strong solvent to remove. Expansion of the glue can also be a problem. If the work is not clamped down tight enough, the polyurethane glue will push apart joints as it expands.
While polyurethane glue may not be the best option for some woodworking projects, it is a good choice for outdoor furniture and anywhere you need a very strong, waterproof bond. When applying polyurethane glue to wood surfaces, they should be wetted down before application to increase the moisture level of the wood and properly activate the glue.
Best Poly Glue
Gorilla Original Gorilla Glue
A common favorite among polyurethane glues is Gorilla Original Gorilla Glue. This excellent glue is unaffected by extreme heat or cold and is great for indoor and outdoor repairs. It creates a strong bond between most common surfaces.
Epoxy resins became commercially available in 1946 and have since become widely used in a variety of industries including protective coatings, laminates, composites, molding, construction, bonding, tooling, casting, and adhesives. Epoxy is available in a variety of different forms that differ mainly in their cure rate. Some will cure in as little as five minutes, while others take hours. The longer the cure rate is, the stronger the bond will be.
Epoxy is a 2-part glue made up of a hardener and a resin that you mix together. Both the hardener and resin are sold in liquid form and come with pumps that dispense specific amounts for proper mixing. When you mixed them together an epoxy is created as a result of a chemical reaction. The resulting epoxy is waterproof and is a good choice for filling in gaps between pieces of wood, especially where other types of wood glue might fail.
Epoxy is overall a great choice for gluing wood together. It is water resistant, withstands shocks and vibrations, is one of the strongest adhesives available, and can be used on a wide variety of materials. However, until it is completely cured it is extremely toxic and flammable, and extra precautions should be used. You should wear a facial respirator, latex gloves, and safety glasses when working with epoxy.
System Three 1100K16
If you need an epoxy with a tensile strength of 7000 pounds per square inch, look no further than System Three 1100K16. This epoxy is so strong that it can even be applied to damp wood. It is unaffected by water, oil, keresone and many other chemicals once it has fully cured.
PVA stands for polyvinyl acetate, and is the most common type of glue available. White glue, yellow glue, and those labeled as wood glue that are readily available at your nearest store are all most likely to be PVA glue. PVA can be categorized into three categories:
- PVA glue 1 is for indoor use only and sets quickly.
- PVA glue 2 can be used indoors and outdoors, is water resistant, and sets quickly.
- PVA glue 3 can be applied at lower temperature, is water resistant, the strongest of the three categories, and takes a longer drying time. Making it a great choice for complex projects.
PVA glue has many benefits as it is widely available, non-toxic and non-flammable, and can be easily cleaned up with water. PVA glue is not the strongest of adhesives and does not take up stain well. PVA glue is not a good choice for a joint that may need to be repaired in the future. The new glue will not adhere to the cured glue.
Best PVA Glue
Gorilla Wood Glue
A classic choice, Gorilla Wood Glue is hard to beat. Offering an easy-to-use applicator bottle and a fast dry time, it's hard to go wrong with this wood glue
Cyanoacrylate (CA) glue, commonly known as super glue, is the fastest setting of all adhesives and forms a clear and waterproof bond without the need for clamping. It comes in a variety of forms and thicknesses, and in some cases it can benefit from the use of an accelerator that increases the drying time on hard acid woods such as oak or maple.
Cyanoacrylate glue can be used in certain aspects of woodworking projects including:
- Anywhere a repair needs to be made, as cyanoacrylate glue will stick to old glue.
- Fast setting purposes where clamping is impossible
- Sealing end grain before staining
- Adding to sawdust to fill cracks or gouges
- Finishing on green or dry wood
- Repairing chips
- As a sealer to eliminate pine holes
- Creating a glue block to join curved pieces of wood
Some downsides are that cyanoacrylate glue tends to run, is not a good choice for any project that will endure vibrations as it is very hard and can fracture under impact. You should avoid using cyanoacrylate glue in complicated assemblies that require a long open time and jobs where glue is a cost issue. Cyanoacrylate glue can get expensive and also requires a strong de-bonding agent to remove.
As with all other wood glues, the wood surface should be clean before application. You should wear safety glasses and latex gloves when applying. Do not spread the glue. Instead let the pressure of the wood being pressed together spread it. The thinner the layer, the faster it will dry. It can dry faster than you can get the wood pressed down if the glue is in too thin of a layer. Only use the smallest amount you need, excessive glue will not add more strength. Avoid touching working surfaces with the tip of the glue container, as this will cause the tip to clog.
Best CA Glue
Glue Masters offers various thin and thick CA glues that should work well for most projects. Common applications include woodworking, model building, carpentry and household repairs.
Hide glue is probably one of the oldest types of glue, and just as it sounds it is made from animal hides. For centuries people have been making hide glue by boiling animal hides in water. As the liquid cools it becomes a solid. The resulting bond is strong and very similar to that of PVA glue, except it is not water proof. Hide glue is non-toxic, will take up stain, and any unused glue that has cooled can be reheated and used normally.
Hide glue is a good choice for veneer work, musical instruments, and general indoor furniture. It is also a popular choice because of its reversibility. By applying heat the glue will loosen, allowing the repair of furniture, especially those that are antiques. So if you are making your next piece of family heirloom furniture, hide glue is probably your best choice.
In modern society, hide glue comes in two different forms. Hide granules that can be melted in a double broiler and then applied hot with a brush, or liquid hide glue that comes in a bottle. Liquid hide glue can be applied in the same way as PVA glue.
Best Hide Glue
Behlen Ground Hide Glue
Our pick for a hide glue you can trust is Behlen Ground Hide Glue. This glue is great for furniture and musical instrument repair and offers excellent sandability. It's the preferred choice among cabinetmakers.
Common Mistakes When Using Wood Glue
Some common mistakes that make using wood glue a hassle include:
- Not cleaning the surfaces before application
- Not applying enough glue, or applying too much glue.
- Not properly lining up joints and edges, especially when using non-reversible wood glue.
- Not properly cleaning wood glue from surfaces before staining.
Regardless of the type of wood glue you choose, be sure that it is right for the project and intended purpose. Follow all safety instructions when applying all wood glues. Buy only the amount of glue you need, as many do not have a very long shelf life.
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