Outside of your tools, woodworking glue is probably the next most important item that you need in your shop. Unfortunately, just picking any glue isn’t the best possible approach because there are many options available.
When choosing your glue, it’s important to consider several factors to ensure the glue you choose will work with your project. Some of the things you need to consider are:
- Does the glue need to be waterproof?
- Does it need to be food safe?
- Do you need several minutes before the glue starts drying in order to get all your parts put together or clamped?
- Why type of finish are you using on your end project?
In this post, I will go through and explain each of the diverse types of glue that is available. I’ll also explain factors to consider for each. At the end of this article you’ll also find a decision tree that will help make the process of choosing the right glue for your project easier. Once you’ve determined the best type of glue for your project, head over to my Best Woodworking Glue page where I’ll show you what I think are the best glues currently on the market.
Types of Glue
This is the oldest form of glue that is still in use today. Historians have found that this glue has been used for more than 8,000 years. Even through all the technology advances that have occurred, this is still one of the most popular glues used by woodworkers.
The different characteristic of this glue is that it is created using animal parts. Glue manufactures purchase bone, tissues and hides from primarily cattle slaughter houses to create the glue.
Once the manufacture has processed hide glue, it comes in the form of a gelatin. The gelatin can be in the form of small pellets or in the shape of cream.
If you decide to go with this glue, you will need to heat the glue up before applying to your project. Heating it up will turn it from it’s gelatin form into a more liquid state that makes it appear as normal glue that can be brush onto your project like you are accustomed to doing.
If you used hide glue during this process, you would only need to heat the joined board up with a hair dryer or heat gun. This would soften up the glue so that is more pliable. Fix your boards to your liking and you are finished! The glue only needs to be heated to about 145 degrees to become fully pliable.
The fact that hide glue has been used for thousands of years should be a good indicator for how well this glue holds up. Numerous studies online have shown this it does an excellent job of holding up when used in several types of joints.
Another positive here is that hide glue does not cause “glue creep”. Glue creep occurs when you join two boards together and it expands beyond the join and becomes visible on the surface. Hide glue shrinks as it begins to dry thus preventing the creep from ever occurring.
Nothing can be more disheartening than to finish a project you’ve put hours of work into to discover glue has dripped or run onto a visible piece of wood. Odds are this sends you off to multiple Google searches to find a solution that will have the least negative impact to your project.
The pleasant thing about wood glue is that it can easily be sanded. Need to remove a bit of excess glue where you applied too much, just give it an easy sanding and it will be gone in no time.
Staining over hide glue also works very well. It will easy accept a stain when applied.
It’s recommended that pieces remained clamped for up to 24 hours to ensure the bond of the glue reaches it’s max strength.
The glue granules can last for years if kept in a cool and dark location. Once mixed, the glue does not last more than a few weeks. It’s recommended that you mix your glue in small batches and just use what you will need at that time.
As you can see, we’ve listed numerous advantages to using hide glue in our woodworking projects. There are some drawbacks to hide glue. Some of these drawbacks will prevent you from being able to use it on some of your projects.
This glue is NOT water resistant. It is not recommended to use this glue in any areas that may see moisture. This includes using it in an area that may have high humidity such as in a bathroom.
Another common complaint for people that use hide glue is the smell. It can have a strong smell once it’s heated up. This is something you can adjust to, but it is a complaint that comes up.
Liquid Hide Glue
This is a newer form of hide glue that was released in the early 2000’s. It has all the same advantages and disadvantages as the older recipes of hide glue. The primary difference in this product is that it does not require granules to be heated prior to use.
One other small difference for this line of product is the shelf life. A bottle of it has an average shelf life of about 12 months.
This is the most popular glue on the market today. PVA glue is Elmer’s glue that you are accustomed to seeing in your school days. Chances are that if you’ve purchased glue from a big box store to do a small wood project around your house, you’ve grabbed some form of a PVA glue off the shelf.
This glue can be picked up in colors of white, yellow and brown. It’s not uncommon to be referred to as “yellow woodworking glue.”
The price, availability and versatility are what makes it the number one option for woodworking. Applying this wood is a breeze. It’s as
simple as picking up a bottle, opening it and applying. There’s no heating needed like you find with hide glue. One nice feature of the glue is that if it’s a bit too thick for you need, you can add a few drops of water to it to help thin it down some.
PVA glue will sufficiently meet most wood projects for your home that will remain indoors. Tests have some that it can handle strength tests of up to 3000 psi, which makes is more than suitable for making furniture in your home.
PVA glue does allow you to paint over it, however, one of the major disadvantages to using it is the fact that you are unable to stain over it. Odds are, all woodworkers have built a project using PVA glue only to find some of it has seeped out from where it was applied. Once it gets onto the surface of your wood it is near impossible to get cleaned up enough so that you can stain your wood and not have a visible glue blotch on your finished product.
It should be noted that PVA glue will absorb into the wood upon appication. This absorption will cause your wood to expand rather quickly. As the glue dries, it will then shrink.
It’s recommended that pieces remained clamped for up to 24 hours to ensure the bond of the glue reaches it’s max strength. Once it has dried, this glue will be clear.
PVA glue has a shelf life of around 1 -2 years depending on the conditions in which it is stored. A cool dry place is recommended.
This glue is NOT full waterproof, therefore it is not recommended to be used in wet or high humidity conditions.
If it freezes, it causes the polymers within the glue to break down which significantly reduces its strength.
Another glue that is gaining popularity in recent years is epoxy. When you purchase it, you find it comes in two containers. One is the glue (or resin) and the other is the hardener. You’ll have to mix the two to use it. It’s important to get the mixture of the resin and hardener correct otherwise you can increase or decrease the time you have to get your components set before it starts hardening.
One advantage to using this glue is that it will bond to pretty much everything. In recent years, there had been a growing use of epoxy to create table tops that are mixed with wood. Typically what will happen is the worker will create a frame to the size of the table they want. Next a live edge slab of wood is placed inside to the leak proof frame.
Finally, epoxy is poured into the frame until it fills in the framed in section. Depending on how much volume the wood takes up within the framed section, there can be a significant amount of resin added. It’s not uncommon to see the resin mixed in 5 gallon buckets prior to being poured.
Another trick to try with these table tops is to mix dyes into the resin. You can get very creative with all of the color choices available. There is even some glow in the dark pigment that you can add for an extra effect.
Once dry, the table will need to be sanded, but it will be the exact same of the frame. The resin will be incredibly strong and hold up to day to day wear.
If you are considering making a table like this that will be around food, make sure the resin you pick up is rated as food safe. Not all epoxy is food safe.
Epoxy is probably the strongest glue that you can find on the market for your projects. It will harden almost as hard as a stone. Additionally, as it dries, it stays the same size so you won’t have to worry about any expanding or shrinking.
Epoxy holds up well to moisture and heavy abuse. If you need some glue to use on outdoor furniture or to fill in some cuts and gouges on a bar top then epoxy is your best choice.
Epoxy works very nicely with stains. It works very well and should give you no problems.
You can sand epoxy, however it is highly recommended that you wear long sleeves and a respirator when sanding.
The cure time for epoxy can vary significantly. It will dry and be strong enough within minutes if you are assembling your project. However, if it’s an important piece, it’s recommended you allow longer. In fact, if you want absolute full-strength curing, you should wait 72 hours after application.
Shelf life estimates vary from brand to brand on epoxy, but the minimium shelf life I could find was around 2-3 years. However, I’ve heard of people having it last for many years beyond that. It again comes down to how you store it. Cool, dry environment is recommended.
Epoxy can be expensive. If you are looking to create large table tops with resin mixed in 5 gallon buckets, I’d recommend looking around for companies that sell their epoxy in bulk quantities.
It can cause problems for people with sensitive skin. I highly recommend using gloves when working with epoxy.
Once cured, it epoxy is set and cannot be reversed. It’s important to make sure you have everything in place the way you want it once you’ve applied it to your project.
Polyurethane glue seems to be the “controversial” product in the market of wood glues. There seems to a strong love hate relationship with this glue. The most popular brand of polyurethane glue that you have heard is Gorilla Glue. It was first introduced to the USA market in the 1990’s.
The glue is water proof and will work on just about any surface you can find. The only materials that it doesn’t work the best on is surfaces that are oily or waxy.
It’s work time is nice at about 20 minutes so it gives you plenty of time to get your pieces set in place.
Due to the chemical structure of this glue, the application process is a bit different than the other glues we’ve looked at. It’s recommend to dampen one side of the surface you are gluing to allow the glue to absorb deeper into the wood to create a tighter bond.
This is one of the areas of debate when it comes to this type of glue. Most tests show that the glue can hold joints up to about 3000 psi, which is plenty strong for any applications around your house.
This glue can only be removed by scraping or sanding once it has dried. I recommend using a wood scraper to remove it.
The glue does not work well with stain. It’s important to make sure you keep the wood contained to nonvisible areas to avoid visible glue blotches.
Most cure time for this glue are estimated at around 8 hours for full strength.
Cure times can be significantly impacted based on the humidity in the air. If you are in a dry climate, your cure time can be much longer.
General shelf lives are listed at 1-2 years, but users have reported success using this glue even beyond that.
Cyanoacrylate is the fancy name for what is common household super glue. This glue is not going to be used in large quantities like some of the other glues we’ve looked at. It’s still a valuable resource that should be present in your shop.
TIP: If you are looking to add some detail to your project, super glue might be an option. I recently created a dining room table that had some minor knot holes an a couple small cracks. Rather than using wood filler or cutting the wood to avoid the cracks, I used black super glue. It was as simple as adding the glue to the holes and then sanding it. It gives a great pop to the wood that is subtle.
Super glue is useful in areas where you need a quick cure time and a strong bond. Many times if can be used to old pieces of wood together where it’s not possible to use clamps.
It’s also a great tool to have when you need to make a repair to piece as bonds to any material, including old glue that may still be on your wood.
The primary disadvantage to using super glue is cost and cure time. Those reasons are why this is primary used as what I call a “specialty glue” where it’s only going to be used in specific scenarios like we’ve discussed above.
Is there a Glue that is Food Safe?
With all the different options available when it comes to woodworking glue, one question that often comes up is “Is there a glue that can be used around food?” The answer to that is, yes!
Titebond makes a glue that has been approved by the FDA as been food safe. The other nice thing about this line of glue is that it is also water proof. So if you are looking for a glue to use on projects in your kitchen, I highly recommend – the Titebond III Wood Glue.