Glue is a surprisingly useful substance. Once you think about it, you realize how most of the furniture, tools, and appliances in your house are most likely held together, at least partly, with an adhesive like glue.
However, when working with any adhesive substance, you’ll also definitely want to think about how much of a hazard it is and whether it will burst into flames if it gets too hot.
As with most of our articles, there’s not a simple yes or no answer to this question. It really all depends on the type of glue and its condition.
In this article, we’ll be taking a deep dive into the various types of glue and let you know which ones can pose a fire threat and which ones are safe.
What Is Glue?
First, we need to understand exactly what glue is. Don’t worry though, we won’t be getting too scientific!
The word ‘glue’ is interchangeable with ‘adhesive’ and it basically refers to any non-metallic liquid substance that can be applied to two separate objects to bind them together.
Naturally occurring glue like tree sap and tar has been used for hundreds of thousands of years by humans and their ancestors. However, nowadays, the majority of the adhesives we use are artificially produced.
Without getting too far into it, the main ingredient in most synthetic glues today is called vinyl acetate, which is produced through a chemical reaction between acetylene and acetic acid.
This vinyl acetate can then produce a polymer in the presence of a catalyst and this polymer gets mixed into various different emulsions to make different types of glue.
Basically, almost all glue starts with the same chemicals and chemical reactions, then is mixed with other chemicals depending on how strong the glue needs to be and what other properties it should have.
It’s worth noting that vinyl acetate on its own is highly flammable. However, there are a lot of other processes and additional substances that reduce the risk of certain glues combusting into flames.
What Makes Glue Flammable?
The main things to note about whether a type of glue is flammable or not is whether it’s water-based and whether it’s dried.
A lot of weaker glues that you’d use for small, lightweight projects will be water-based, and these are almost always not flammable.
However, this changes between the moment the glue is initially applied to a surface and when it eventually dries up. Interestingly, most household glues are more flammable when they’re still wet.
This is because the solvents they use are the flammable components of the glue and these flash off as it dries. Therefore, when the glue dries it is no longer flammable and is much less likely to pose a threat of combustion.
That’s one of the things that make these household glues so much safer than industrial strength ones.
However, these aren’t the only factors in determining the flammability of glue. Let’s take a closer look at the most common types of glue:
Different Types Of Glue
Now that we’ve established what glue is and we know a little more about how it’s made, let’s go over some of the main types of glue and discuss whether or not they’re flammable.
White Craft Glue
This is the type of glue that we all probably grew up using for arts and crafts as children. It’s great for use on light materials like paper and cardboard but isn’t strong enough to use for any proper construction.
This is a water-based adhesive so, as we established before, it is not flammable. Even when it’s still wet and has a slightly greater chance of catching on fire, white craft glue is designed to be child friendly and so it has a very low toxicity and poses little threat of combustion.
Super glue is an adhesive that a lot of people keep in their garages and toolboxes for repairs and minor projects. It’s a very powerful adhesive that can be used in the home, but poses a slightly greater risk of toxicity and flammability.
In contrast to white craft glue, super glue is flammable even if it is cured. Even more dangerously, when super glue burns it produces a harmful, noxious gas. In fact, super glue is so highly flammable that it can set fire to a cotton ball without even any additional heat being applied!
This doesn’t mean you can’t use super glue in your home, however. Make sure you read the packaging carefully and research which materials are safe to use with super glue. It might also seem obvious but you should definitely avoid having any open flames near a tube of super glue.
This adhesive company has made a name for itself in the past few decades as being one of the best brands for repairing things in the home.
Similar to super glue, Gorilla Glue is highly flammable when wet, but significantly less so when dry. If Gorilla Glue catches on fire while still wet, it will emit some dangerous, noxious gases that can be damaging to a person’s health.
However, once it’s dry, the glue can withstand a lot of heat and water, and is much less likely to combust. That’s what makes this such a popular brand for reliable repairs.
A significantly less construction-based and more cosmetic glue, nail glue is designed to be as safe for humans as possible.
However, much like the previous glues we’ve looked at, it is still flammable when wet and will produce toxic fumes while burning. Once dry, the nail glue’s solvents will have flashed off and it will no longer be flammable.
Hot glue guns are, by themselves, pretty dangerous to use and you’ll need to be extremely careful to not let them touch your skin while hot.
However, the benefit of being able to work with this glue while it’s hot is that it is not flammable, whether wet or dry. This non-flammability and the lack of toxic chemicals used in making hot glues make them a universal favorite for home construction projects.
Frequently Asked Questions
Is Glue Still Flammable When Dry?
Essentially, no, glue tends to lose its flammability once it has dried. The solvents that are used to make artificial glue are the parts that are flammable and are what can make the glue combust when it’s still wet.
However, when the glue dries the solvents flash off and leave the glue safe and non-flammable. Despite this, it’s worth noting that glue can still burn when exposed to enough heat - the same is true of any substance. It simply becomes a lot less likely to burn when it’s dry.
Is Gorilla Glue A Fire Hazard?
Gorilla Glue can definitely pose a fire hazard while using it and when the glue is still wet. However, once it’s dry, Gorilla Glue is one of the safest home adhesives to use because it is designed to be resistant to heat and water.
What Glues Are Flammable?
According to our research, the majority of glues are flammable when wet. These include super glue, Gorilla Glue, nail glue, and canister adhesives.
However, adhesives like white craft glue and hot glue are significantly less flammable and are unlikely to catch on fire even while still dry. The general rule of thumb for all glue is that it becomes non-flammable once it has dried.
So there you have it: the definitive guide to glues and their flammability. The main thing to take away from this article is that pretty much all types of glue are safe to use and will not be flammable once dried.
All this means is that you should take extra care while carrying out any work with glue to keep it away from any open flames.
You shouldn’t be afraid to use any of the glue varieties we’ve mentioned in this article, just make sure you check the packaging carefully and note any materials or substances that are dangerous to use with that type of glue.