Hot Glue: Everything You Need to Know

When it comes to glues and adhesives, one type that you might be familiar with his hot glue. Are you looking for the best glue for arts and crafts? If so, you have definitely come to the right place, because hot glue is a prime choice.

What we want to do right now is to teach you everything that there is to know about hot glue, and this includes what it is when it was invented, how it works, how strong it is, how it cures, and so much more. Let’s talk hot glue!

What is Hot Glue?

So, what exactly is hot glue? Hot glue is also known as hot melt adhesive or HMA for short. Technically speaking, this is a specific type of thermoplastic adhesive. As you can tell by the name of it, hot glue, a thermoplastic, has to do with temperature, hence the word thermo. To be clear, hot glue is a type of plastic.

The main ingredients in hot glue include ethylene-vinyl acetate (EVA), polyolefins, polyamides and polyesters, styrene block copolymers, polyethylene, and ethylene-methyl acrylate (EMA), and/or ethylene n-butyl acrylate (EnBA). While hot glue is technically an adhesive, it is not like other glues that use special ingredients to adhere to materials, but rather use the process of hot and melted plastic cooling down and solidifying, thus forming a bond.

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Moreover, unlike other types of adhesive that come in liquid format, need to be dispensed from a tube or bottle, and then cure on the materials, hot glue in its normal form is totally solid. This glue comes in the form of clear and solid cylindrical sticks, more or less just chunks of plastic, which are then melted using a special tool that we will talk about below.

When Was Hot Glue Invented?

What is interesting to note is that hot glue has not been around for all that long, and in fact, this month, May of 2021, marks the fifty year anniversary of its invention. Hot glue was first invented in May of 1971 by a man named Carl Weller.

In 1971, Carl Weller filed a patent for a tool that is used to dispense a thermoplastic material, or in other words, a gun that heats up sticks of adhesive plastic up to their melting point, complete with a trigger and an application nozzle.

Once the original glue gun was patented and made available to the greater public, the use of hot glue as an adhesive really took off. Various versions and models of glue guns were then invented and patented throughout the early 1970s and onward. Ever since its invention, hot glue has been used for a wide variety of applications.

How Hot Glue Works

What is really cool about hot glue is that this is an adhesive that works differently from virtually all other adhesives out there. All adhesives out there are water based or non water based, but something that they all have in common is that they are in liquid form in their normal state.

When it comes to hot glue, the plastic itself is in a solid form, not liquid form, when it is at room temperature.

This is why it is known as hot glue, because it needs to be heated up in order to melt into a liquid form that can then be applied to a surface.

A hot glue gun with a strong heating element is used to heat the glue. When the trigger on the hot glue gun is pulled, the melted thermoplastic adhesive is dispensed.

Now, what is important to note is that water-based adhesives cure by evaporation. They harden as the moisture leaves them. Non-water based adhesives often cure when they come into contact with moisture or UV light.

However, hot glue is not like this at all, and it really does not cure.

Curing is generally seen as the process of hardening due to a chemical reaction.

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Well, although cooling down from a hot temperature could be considered a chemical reaction, it really is not.

Hot glue bonds materials together simply by cooling down. When hot glue, AKA that plastic, cools down, it solidifies into a solid and very hard material, plastic.

Curing Process

As we have noted above, hot glue really does not cure at all. Remember that curing is defined as a chemical reaction between agents that results in the hardening of the materials. Now, cooling down and heating up, although those things are scientific in nature, and could be seen as chemical reactions, they really are not.

Therefore, while hot glue does solidify when it cools down, this has to do with the properties of the ingredients, as well as the difference between materials in liquid and solid states. The process of molten plastic cooling down and solidifying really is not what curing is at all. So, although hot glue does harden and solidify, it does not cure.

Do keep in mind that if you look this up online, products and informational articles will talk about curing times of hot glue, but this is just because “curing” is the general term used for the process of glue solidifying.

This is of course a very fine line, one that most people would not bother talking about, but that said, cooling and curing are technically different.

How Strong is Hot Glue

What needs to be said here is that technically speaking, that thermoplastic itself is extremely strong.

In general, hot glue can handle between 600 and 700 pounds of weight, and thus it can bear a good bit of weight.

However, it does need to be said that while hot glue can handle a good bit of weight, it cannot deal with impacts very well.

So, if you used hot glue to bond two things together, you could probably snap it in half with some muscle power.

It’s important to note that hot glue is of course plastic and yes, plastic is very strong.

The bottom line here is that the glue itself, the solidified plastic, is strong on its own, but that said, the bond which it forms is not amazing.

Strictly speaking, although it is said that hot glue can be just as strong as epoxy, we really do not see this as being the case, because epoxy tends to be more impact resistant and better for strength applications.

When it comes down to it, you would really never use hot glue for strength applications.

It’s not something you would use to bond heavy objects, to make repairs that need to last, for anything to do with moving parts, or for anything that needs to be able to handle impact. Also keep in mind that hot glue is not overly heat resistant.

Keep in mind that hot glue is in no way an industrial or structural adhesive.

What is Hot Glue Used for

Now that you know what hot glue is, what it is made of, and how strong it is, let’s figure out what it is used for. First, let’s quickly talk about the types of materials that hot glue can bond to, and then talk about some of the primary applications of hot melt adhesives, using real life scenarios and examples.

What Materials can Hot Glue Bond

One of the most important things that you need to know is that hot glue is designed mainly for porous surfaces.

For the most part, hot glue will not stick to very smooth surfaces. Now hot glue will stick to somewhat smooth surface is, but not extremely smooth surfaces. How cool also won’t bond well with any kind of surface that is greasy or wet.

Anything that is extremely smooth and flat like metal, silicone, vinyl, or wax is not something that you will be able to bond using hot glue. In other words, there has to be some kind of texture for that plastic to stick to something that it can grab onto.

If there’s no kind of porosity involved when the hot glue dries, it’s simply going to peel right off of that surface because there is no texture for it to hold onto.

That said, hot glue can bond a variety of porous and minimally porous materials such as paper, construction paper, cardboard, wood, engineered wood, fabric, various plastics, foam, stone, some types of glass, and more.

Now what is interesting to note here is that for some reason there are many sources out there that claim that hot glue sticks very well to non-porous and smooth materials.

Folks, anybody who says this simply doesn’t know what they’re talking about because it is not true in any way, shape, or form. If you have an extremely smooth piece of metal and you put hot glue on it, by the time that hot glue is cooled down and solidified, you will be able to literally pull it right off of that metal sheet.

Primary Applications

Now that we know what hot glue can stick to and what it can’t stick to, let’s take a look at some real life examples of the primary applications of hot glue.

Have your about to find out. Hot glue can be used for a variety of purposes, but that said, none of them are really structural in nature. They’re all relatively lightweight tasks.

So, what is hot glue used for?

• When it comes to home use in school, use the most common use for hot glue is for arts and crafts. It’s very easy to use. It bonds quickly. It’s relatively safe, and it works really well to glue together all sorts of arts and crafts. Materials like papers, belts, plastic, faux gemstones, and other such things.
• Hot glue is used to glue together the spines of books.
• One of the other very common uses for hot glue is to close the flaps of corrugated boxes and paper cartoons. In other words, the box industry uses hot glue.
• Hot glue is also sometimes used in the construction of low end furniture, such as to glue together MDF boards. It’s not the number one type of adhesive to use for furniture, but it’s definitely an option.
• Hot melt adhesive may also be used to glue the wires other parts inside of phones and other electrical devices.

Advantages of Hot Glue

Let’s quickly sum up what advantages you get when you use hot glue instead of other glues or adhesives.

• Very little waste
• Long shelf life
• Very few environmental concerns for disposal
• Very rap[id drying
• Does not contain volatile organic compounds
• Waterproof
• Resistant to solvents
• No loss of thickness during cooling
• Can be mixed with color to create colored glue

Popular Brands

If you’re going to buy hot glue, you obviously want the best of the best, and this means sticking with the right brands. Some of the best hot glue brands to consider include Gorilla Glue, Surebonder, Ad-Tech, Ewparts, and Artellius.

How to Remove Hot Glue

If you happen to get hot glue on your clothes or your hands, there are a few easy ways to remove it. First off, if you got the hot glue on a flat and smooth surface, realistically, you should be able to just grab it and pull it right off. Hot glue does not bond well with non-porous materials, so if you can get a knife or something pointy under a corner, you should be able to just peel it off.

Moreover, hot glue is not overly temperature resistant. So, using a blow dryer to heat it up until it softens should be more than enough to allow you to remove it. If the hot glue is very stubborn, saturate the area in rubbing alcohol, as this will soften the hold. Pure alcohol is the number one way to quickly as easily removed dried hot glue.

Bad Things About Hot Glue

There are quite a few disadvantages of hot glue that you need to be aware of, so let’s take a quick look.

Heat Resistance

Hot glue is made liquid via melting, therefore, it is safe to say that once dried, hot glue is not very temperature resistant. The low temperature varieties can become liquid in temperatures as low as 80 degrees Celsius. Even if they don’t totally melt due to high temperatures, extreme heat will still impact bond strength.

Impact Resistance

As has been noted, this type of glue just does not have good impact resistance. It is not designed to bear weight, to be used on moving components, or really anything to do with structural integrity.

Can be Messy

Although it gets easier with practice, it’s pretty easy to make a huge mess with a hot glue gun, but that said, at least it is easy to clean up.

Requires Special Tools

Unlike with most other adhesives, hot glue requires electricity and a hot glue gun to function.

Non-porous surfaces

Although it depends on the specific material, in general, hot glue does not bond well to very smooth surfaces.

Conclusion

There you have it folks, all of the most important information that you need to know about hot glue. Now that you know what this stuff is all about, you can make a much more informed decision as to what type of glue you need for your next project.