Every woodworking shop uses glue on almost every project, even if the workpieces are also being joined by screws. Pocket hole joinery creates strong bonds, but a little glue adds that extra measure of joint strength. Clamps are as ubiquitous in woodworking shops as workpieces being glued need clamping while the glue dries.
Just as we keep a variety of clamps in our shops, pipe clamps, bar clamps, C-clamps, etc., most of us keep at least a couple of glues in our shop, too. Just as we often write “the right tool for the right job,” the same can be said for glue – “the right glue for the right job.”
Today we’ll distinguish between glues, discuss their best uses, and mention their disadvantages.
Types of Wood Glues
There are three main types of glues for use in your woodworking shop. Each has its own compositional base, and each has its best use that will depend on the materials being joined and where the glue will be used:
- PVA – polyvinyl acetate, also known as wood glue, the most well-known of which is Elmer’s Glue, the white glue we all use;
- Polyurethane – a glue commonly called Gorilla Glue because it was the first company to bring the glue to the US market; and,
- Aliphatic – a synthetic resin glue of which Titebond is the most well known, a synthetic adhesive with a yellow glue color and creamy consistency.
Wood glues are designed to penetrate the grain and wood fibers, and as such, they create a deep and stronger bond than the wood itself – strength of wood plus strength of glue.
As regards these three main types of glues, Gorilla Glue straddles two categories. Its first glue brought to the US market was and is a polyurethane glue; it has also introduced a PVA glue, Gorilla Wood Glue, to the market.
It is a worthy addition to the choice of wood glues – reliable and very strong, water-based, with a thick consistency that makes spreading of it on the workpieces easy. It is a good choice for both softwoods and hardwoods, as well as wood composites. It does not expand, dries quickly, and leaves clean lines.
While Gorilla Wood Glue is nearly clear, aliphatic glues like Titebond are yellow in color. It is odorless, dries quickly to a natural finish, and can be sanded to provide an invisible bond between the wood pieces. Each glue provides a strong bond, with the main difference between the two types of glue being that Titebond is waterproof while Gorilla Wood Glue is highly water-resistant.
Wood Glue
Sometimes referred to as yellow glue, we’re pretty sure wood glue is in every woodworking shop. We know it, we use it, we know that creamy feel on our fingers, and we know how effective it is in bonding wood pieces together.
It is:
- Easy to use
- Has about a 30-minute work time before it begins to harden
- Easy to clean up with water
However, it has some minor disadvantages:
- It is limited to its name – wood glue – and works only on wood
- Some kinds of wood glue can be used only inside, away from moisture sources
If you are gluing along sides or faces, it’s the right glue for the right job. Apply the glue to both workpieces and brush to cover the entire surface evenly. Give the pieces a good clamping for a couple of hours, and don’t stress the joint for at least 24 hours.
Differences, Advantages, and Disadvantages Between Gorilla Wood Glue and Titebond
We like Titebond glue and have used it on many projects. Titebond, carpenter’s glue, yellow glue – it goes by a variety of names that we all know.
Titebond Original is the industry standard for glue, used for interior purposes only. Unstressed joints should be clamped for 30 – 60 minutes and allowed to cure for 24 hours. Stressed joints should be clamped for 24 hours and allowed an additional 24 hours for curing. Excess glue can be wiped away with a damp cloth when it’s wet or a sharp chisel if it has dried.
Titebond II is the right choice for exterior purposes because of its water resistance qualities. It has the same clamping and curing requirements as Titebond Original.
Titebond III is an even better choice for exterior use because it is waterproof. As such, it has the advantage over Gorilla Wood Glue which is only highly water-resistant. Cleaning, clamping, and curing properties are the same for Titebond III as for the Original and Titebond II.
While Gorilla Wood Glue dries clear, none of the Titebond glues do. Titebond Original will dry to a pale yellow color; Titebond II will dry to a darker yellow color, and Titebond III will dry to a dark brown color.
Gorilla Wood Glue is a PVA glue. It dries relatively hard, but not as hard as polyurethane glue, the original Gorilla Glue type.
Aliphatic glues like Titebond are synthetic formulas particularly good for wood-to-wood bonding, as we have noted. Its chemical composition is similar to that of PVA glues, but chemical modifications are made to the aliphatic resins to make them stronger and more moisture-proof.
Shelf Life of Wood Glues
Glue manufacturers are pretty conscientious about offering shelf life advice. They do so out of concern for their customers but also to limit their liability in cases where customers are not as careful with storage as they should be. When it comes to wood glue and the safety of your projects, expect no longer than a 1-2 year shelf life.
It is possible that your glue’s usefulness and safe use may last longer, especially if your shop is heated. The rating on shelf life has to do with the number of freezes and thaws glue undergoes. So, if there are no freezes, no expansion and contraction of the glue, the 1-2 year shelf life could be stretched.
Remember, though, that the safety of your projects (chairs and tables, for instance, that hold people and food) is at stake, and erring on the side of caution as that 1-2 year period tolls is a good thing.
Polyurethane Glues
We have not mentioned polyurethane glues yet, although they are a very good bonding agent for woods. In fact, they are a versatile glue that will bond stone, ceramics, metal, glass, concrete, and more materials.
Polyurethane glues expand to fit the spaces they are used in and create a strong bond. The expansions, though, are a double-edged sword. While it may be desired in some instances, when bonding 2 smooth surfaces, it can push the pieces apart, the opposite of the effect you are trying to facilitate.
In addition, they:
- Require moisture to cure
- They have a shorter working period of only about 15 minutes vs. 30 minutes for wood glues
- Clean-up requires paint thinner, whereas wood glue can be wiped with a damp cloth before it dries
- A shorter shelf-life of about 1 year vs. the 1-2 years of wood glues.
When we mention wood glues, we are referring to PVA and Aliphatic glues, and in the case of this article, we mean Gorilla Wood Glue (PVA glue) and Titebond (an aliphatic glue).
Polyurethane glues, with their shorter working period, can be advantageous for little projects but can cause problems for larger glue-ups. Since this piece is specifically about wood glue, though, we’ve focused our discussion on PVA and Aliphatic types since they are the ones we remember from our school days (Elmer’s Glue, the white craft glue we used) and the “yellow” glue we’ve come to know in our woodworking shop.
The disadvantages of wood glue have more to do with location (interior use vs. exterior use) and the degree of water resistance.
While we were not able to find a video that addressed the specific question asked in this article, we did find one that tests the difference between a PVA glue (Elmer’s) and an aliphatic glue (Titebond).
We believe glue should be used in all woodworking projects when wood is being joined. Pocket hole joints don’t preclude the use of glue as a further bonding agent. We keep wood glue handy in a couple of types, and our woodworking shop is full of clamps. A belt and suspenders approach will keep your woodworking pants from falling down, so to speak.
So, keep your shelf stocked, and be sure to check the dates of manufacture and purchase on the containers. Manufacturers tell you how long their products can reliably and safely last, and you should heed their suggestions. If your shop is heated, though, you have a little bit extra time.