When you get into the knifemaking world, the questions appear non-stop. In this article, I will talk about the best glue choice for a knife handle and provide you helpful tips for successful gluing. Since I realized that many people are arguing on this topic, I decided to analyze both views and give you the best possible answer.
So, what is the best glue for a knife handle? Epoxy is generally considered to be the best glue choice for a knife handle. Epoxy is adhesive and typically comes in two parts, known as a resin and hardener. The mixing of these two provides excellent gluing properties for attaching the handle to the tang of the blade.
Next, we will learn more about epoxy, its use in knife making, and finally, give you some gluing tips so you can do this the best you can.
Epoxy Fundamentals for Knifemaking
Epoxy is actually a synthetic resin that is used for a variety of different purposes, including knife making. Epoxy is made by mixing two matched components, a resin, and a hardener. When these two are mixed, a chemical reaction is set in motion which typically lasts several couples of hours. After mixing a resin with a hardener, the material changes from liquid to solid-state.
In terms of a ratio of resin to hardener, 1:1 is generally recommended, although it may vary sometimes, depending on the material. This is why is extremely important to measure them accurately, otherwise, it won’t cure properly. Note that epoxy has different gluing properties and its application depends on the manufacturer’s specifications.
Factors such as hardness, duration of the curing process, viscosity play a crucial role in determining which type of epoxy you need for knife making. Note that epoxy is very sensitive to temperature, so working in a cold shop won’t be the same as working in a warm environment. When it comes to terminology, you may come across terms like pot life and working life.
Pot life refers to the required time for an initially mixed viscosity to double or quadruple, depending on the viscosity level of the product. Timing starts from the moment of mixing and it is measured at room temperature. Another way of defining it is the amount of time mixed epoxy can sit before it starts being usable.
On the other side, working life refers to the amount of time an epoxy stays low in viscosity that it can still be used for a certain application. You could also say that working life is the amount of time mixed epoxy can sit in a joint before it stops being usable. Many people think these two are the same but they aren’t.
As you may already know, the chemical reaction between resin and hardener creates heat which speeds up the curing of the epoxy. So, when the epoxy is sitting in a mixing cup, it will get gummy and unworkable much quicker than it will when it spreads out.
Also, every knifemaker should understand the cure time of epoxy, which is generally temperature-dependent. Most manufacturers specify 70 degrees for their times so if your ambient temperature is low, the longer it will take epoxy to cure. Another fact worth mentioning is that epoxy degrades over time. If you left epoxy on the shelf for months and months, chances are it won’t cure as hard or quickly as they supposed to.
This was my problem in the beginning. I have often wondered how long does it sit there and when I used it I realized that I should throw it out. So, if you are not sure how long did you have an epoxy, just dump it and buy a new one.
Some epoxies cure very hard but these tend to be also brittle. Again, different formulations will vary. My recommendation is to check your manufacturer’s datasheet. Just because the epoxy is rated by particular strength doesn’t mean it is going to be strong in all applications. Moreover, hardness tends to increase shear strength, whereas flexibility increases shock-resistance and peel strength.
One of the most important things you have to understand is that whatever epoxy you may use, surface preparation is the key to success. It is considered to be 80% of the game, no matter what epoxy you use.
The good news is that you can now find epoxy in most DIY stores and at many specialist dealers. However, you have a much greater choice when you order via the internet. Chances are that online you will probably find the biggest selection of high-quality epoxies for many different applications.
For a beginner knifemaker, starting to work with epoxy may seem a little expensive but trust me, using the cheap glue for a knife handle is even more expensive as it can ruin your hard work. Note that some epoxies can contain chemicals that are hazardous to health. If your material doesn’t cure completely or it is difficult to mix, these solvents can evaporate.
In the next paragraph, I will analyze the most popular epoxies used in knife making so you can decide for yourself which one should you buy.
What Is the Best Epoxy for a Knife Handle?
While there are various measures of the qualities of epoxies, the only thing that matters to a knifemaker is how well it holds in knife making applications. With all that said, three options come to my mind:
- J-B Weld Pro Size ClearWeld 5 Minute Set Epoxy (affiliate link)
I have personally tested and used all of them and I must say that it is very hard to put one aside and say it is the best. However, if I had to, it would be the G/Flex Epoxy. I am using that one for a long time and could not be happier with it.
In terms of the Devcon epoxy, the glue line is fine, but under the microscope, I noticed some tiny gaps on one side. However, it may just be that I didn’t apply it perfectly right there at the edge.
When comes to J-B Weld, I noticed that sometimes it leaves a thicker glue line and is visible on one side. However, it is thinner than I thought it would be, but will probably always show something if used for handle slabs.
A lot of people asked me about the Gorilla glue, so I will also share my own experience with it. Over time, I realized that Gorilla glue is not gap-filling, which can be a problem for a knifemaker. If you use it, make sure it fits almost perfectly for the particular surface. You will also need to clamp it much harder than you would epoxy. Usually, the tighter the clamping, the better.
Epoxy vs Super Glue for Knifemaking
Both are popular names for various products that cover a broad range of adhesives. Each has its own specific chemical composition and recommended use. While they have some common applications, they are most effective when they are used for their specific purpose. The greatest difference is that epoxy is made from two components (a resin and a hardener) while super glue is composed of only one component, cyanoacrylate that hardens quickly with exposure to moisture.
While both of them form a strong bond, epoxy is considered to be a superior option in knife making. Epoxy has greater shear strength, structural strength, and also fills voids between parts. All that makes it ideal for attaching the handle on the blade.
In terms of cleaning up, epoxy should be removed with white vinegar or acetone before it hardens. Otherwise, it is extremely difficult to remove it without damaging the knife handle. On the other side, Super Glue can be removed in both liquid or solid-state with acetone or gamma-butyrolactone. Note that both should be used in well-ventilated workshops. For better safety, wearing rubber gloves and eye protection during the work with these chemicals is recommended.
Epoxy Gluing Tips
Finally, I want to give you some tips about epoxy gluing. Just because I made a lot of mistakes in the beginning phases, that doesn’t matter you also have to. Remember knifemakers, it is much better to learn from the mistakes other people made than from your own. So, here are several tips to keep in mind when working with epoxy:
- The number one and also the most important advice is to you have to properly clean the surface before you use any glue, not just epoxy. You can do that with acetone or soap and water.
- After you cleaned the surface, DO NOT TOUCH IT.
- Scuff up the surface that you will be epoxying. This increases the surface area and also gives more 3D area for the epoxy to cling to.
- Glue as quickly as possible after you prepared the surface. The more you wait, the more surface is likely to pick up dust or to oxidize.
- Always follow the manufacturer’s recommendation about mix ratios between a resin and hardener
- Don’t clamp it too hard as you can squeeze epoxy out of a joint