There’s a lot of truth to that old saying “If it moves and shouldn’t, use duct tape.” But sometimes, duct tape just won’t do. When you need something stronger, more resilient, and altogether longer lasting than a strip of tape, adhesives like epoxy and super glue make great options. Suitable for use in both the home and in industrial settings, epoxy and super glue can make fixing and securing bonds a breeze. But when should you use epoxy, and when should you use super glue? If you’re used to grabbing whichever is nearest to hand, you might be making a mistake. While both share the same general purpose, their applications, uses, and properties are quite different. If you’ve ever wondered about the difference between epoxy and super glue, find out now as take a look at everything there is to know about epoxy vs. super glue.
What is Super Glue?
Super glue is a type of compound cyanoacrylate. Usually, it’ll be made of either Methyl 2-cyanoacrylate (which has a molecular weight of 111) or Ethyl 2-cyanoacrylate (which has a molecular weight of 125). If that means nothing to you, don’t worry. Knowing the chemical composition of a product might be impressive, but it’s not strictly speaking necessary in order to understand what it is and what it does. The most important thing you need to know about super glue is that it’s a thin, watery, liquid adhesive that’s resistant to water and capable of hardening at a much faster rate than most adhesives. In the home, super glue is typically used for joining furniture, appliances, or woodwork.
What is Epoxy?
As Difference Between explains, Epoxy is a thermosetting polymer created by a manual reaction of a resin and a hardener, in which the resin is an epoxide and the hardener is a polyamine. The resin and hardener are mixed in different proportions according to the intended use. The more hardener there is, the stronger the compound and the longer it will take to set. Epoxy is exceptionally water-resistant and even has the ability to bond underwater, making it a popular choice in the shipping industry. In the home, it’s used for both furniture and heavy appliances.
Which is Best?
When it comes to picking whether epoxy or super glue is best, there’s no simple answer. In some situations, epoxy will be the best option. In others, you’ll be better off using super glue. To figure out whether you should be using epoxy or super glue, you’ll need to consider things like…
The length of time it takes to create a bond (commonly known as working time) is more crucial than you might think. If you’re working on a big project, a longer working time is usually preferable as this will give you more time to set joints, etc. If you’re working on a small project, a short working time is usually better. If you’re working with epoxy, you can expect a working time of 5 minutes to 12 hours, depending on the amount of hardener used in the product. In contrast, super glue has a working time of just seconds. If you need a quick fix on a small project, super glue is usually the better choice. If you’re working on a large assembly or fixing a complex joint, the longer working time of epoxy is more desirable.
As Glue Insider writes, epoxy tends to be stronger than glue. It forms a powerful, durable bond on a wide variety of surfaces, and is capable of handling plenty of pressure. Super glue tends to form a more moderate bond. Although it’s strong, it’s less durable than epoxy and less suitable for certain surfaces.
Due to the strength of its bond and its extended working time, epoxy is a popular choice in industry. In addition to being used as an adhesive, it’s also commonly used as insulation for electronics, a coating for composites and metal, in model making, and in other large-scale industrial purposes. Super glue tends to be used for smaller projects, including surgery, small parts assembly, and wood finishes. Both adhesives can be used on surfaces like plastic, rubber, ceramic, fabric, leather, and glass. However, their different properties will result in different binding strengths, depending on the surface. Super glue tends to form a weak bond with glass, so it’s generally not used on silica. It can also have a chemical reaction to cotton or wool, something that can potentially burn the material or even cause injury.
As Hunker explains, while both super glue and epoxy are capable of forming a strong bond, super glue has a very low shear strength. As a result, it will help bonded parts resist direct pulling but not off-angle stress. By contrast, epoxy has a huge amount of structural strength.
After epoxy dries, it becomes almost impossible to remove without causing damage to the surface it’s been applied to. Before it hardens, it can be removed relatively easily with white vinegar or acetone. Super glue, by contrast, can be removed both before and after it’s dried using gamma-butyrolactone (GBL) or acetone.
Although the life span of epoxy shortens once it’s opened, it can still last for several years thanks to its resistance to water, moisture, and air. Super glue has a comparatively shorter shelf life: regardless of whether it’s open or not, its low resistance to air and moisture renders it useless after around a year.
Both epoxy and super glue are chemical compounds. As a consequence, neither are completely risk-free. Epoxy carries an allergy risk and should only be used in well-ventilated areas. Any exposure to the skin should be avoided. Super glue should also only be used in a ventilated area while wearing protective clothing. If it comes into contact with skin, it can bond to the tissue immediately. If inhaled, it can act as an eye, nose, and throat irritant. Due to the risk of a chemical reaction and possible combustion when super glue comes into contact with cotton or wool, care should be taken when using it on certain surfaces.
Both super glue and epoxy are excellent adhesives with a range of applications. As to which one is best… it really depends. If you want to quickly bond a crack in a piece of furniture, super glue is likely to be your best option. If you’re working on a large project in an industrial setting, epoxy will usually be preferable.