Home » Polyurethane Glue Guide – Everything You Need to Know

Polyurethane Glue Guide – Everything You Need to Know

Are you looking for the best glue for wood, plastic, metal, and other materials? If so, you definitely come to the right place. If you are building something or making repairs, something that you may have the use for is glue.

There are of course many different kinds of glue out there, so choosing the right one can be a difficult choice.

The type of glue we’re here to talk about today is polyurethane glue. This is a very special type of glue that has many applications, so let’s take a look.

Polyurethane Glue Guide

What is polyurethane glue

First off, let’s find out exactly what polyurethane glue is. This type of adhesive may also be referred to as a PU adhesive. This is a special type of adhesive often used for higher strength constructions, one that can be used for applications that require rigidity and flexibility.

These are types of adhesives that are known as thermoplastic glues, or a polymer, that contains replicas of organic chain units linked to urethane links. The main thing to take note of here is that polyurethane glue is based on polymers. However, they may often contain other additives.

What is important to note here is that you can find both one part and two part polyurethane adhesives. The one component adhesives already feature everything mixed together in the container, whereas the two component polyurethane glues require you to precisely mix both of the components together.

What also needs to be said here is that how flexible or rigid the final product is, well, depend on exactly what the polyurethane glue is made out of. However, with that being said, polyurethane polymers are formed by the reaction of isocyanate and polyol.

In terms of its applications due to its versatility and ability to stick to both porous and non-porous materials, there are a lot of things that polyurethane glue can be used for. In terms of how polyurethane glue becomes solid one dispensed, this is something we will talk about further below.

When was polyurethane glue invented

Professor Dr. Otto Bayer was the man who invented polyurethanes, and he did so back in the 1930s. He was a science and doctor who worked with plastic, doing lots of research in terms of the properties and possible benefits of various plastic types. With that being said, in terms of being used as glue or adhesive, polyurethane did not become popular until the last 20 years or so.

That said, it was used as an adhesive before that, but not very widely, especially not by the greater public. However, in the last couple of decades, polyurethane glue has become extremely popular due to its versatility as it can be used with very many different materials, including both porous and non porous materials.

How does polyurethane glue work

As mentioned above, polyurethane glue works by creating a chemical reaction between two components, isocyanate and polyol. Keep in mind that here we are talking about one part polyurethane glue, not to put polyurethane glue as the curing process for both is not the same. When combined with just a little bit of heat and moisture, the curing process will begin. When these components are exposed to moisture, they will begin to cure.

However, another important component is heat, as the polyurethane glue starts to set, it absorbs heat energy that helps the power this chemical reaction, thus crosslinking the molecules to make a very strong network of chemical bonds.

The most important thing that you need to be aware of here is that because polyurethane glue requires moisture to start curing, you will have to mist the surface before applying the glue, and you will want to slightly mist the glue after it has been applied. Of course, if you have one component polyurethane glue, there is nothing that you will need to do before dispensing it.

However, if you have two component polyurethane glue, you will need to precisely mix together both of the components before you can use it for anything. Something we will discuss in the curing process section below is that the curing process for one part, polyurethane glue and two part polyurethane glue is different. Two part polyurethane glue generally does not require external factors to begin curing.

The curing process

Although the curing process for both one part and two part polyurethane glues are very simple, the fact of the matter is that they are not the same. Let’s take a look at exactly how these polyurethane glues cure.

One Part Polyurethane Glue

As mentioned before, one part polyurethane glue requires moisture and a little bit of heat in order to cure. Once the components are exposed to moisture, the curing process will begin and as the curing process happens, a little bit of heat is created, which also helps to spur on the process. In terms of the working time that you have at your disposal, you have about 15 minutes to work with this type of polyurethane glue.

You can expect polyurethane glue to take anywhere from 24 to 48 hours to fully cure, depending on the temperature and moisture level. Do you also need to keep in mind that Poly fit urethane glue needs to be clamped together very tightly. The reason for this is because polyurethane glue tends to foam and expand as it cures, and this can push components being glued together apart. Clamping is required both to hold the components together and to prevent them from being pushed apart as the glue cures.

Two Part Polyurethane Glue

In terms of curing Poly year two part polyurethane glue is a bit easier to work with and the reason for this is that unlike one part polyurethane glue two part polyurethane glue did not require any external factors to cure. Two part polyurethane glue contains 2 special components which when mixed together will spur on the curing process.

However, in terms of applications and which one is used more, it is one component polyurethane glue. When it comes to polyurethane glue, you won’t find many people using two component varieties as they can be extremely difficult to use and very messy too.

How strong is polyurethane glue

Something that you might like to know about polyurethane glue is the fact that it is indeed very strong. In terms of strength when compared to other glues, this is. This type is definitely up there with the best of them. Now one type of glue that polyurethane glue is not quite as strong as is epoxy, particularly two component epoxies.

In terms of overall strength at room temperature, normal polyurethane glue can handle about 3,500 pounds per square inch. Therefore, as you can tell, indeed it is quite strong, definitely stronger than normal wood glue or yellow glue. Moreover, polyurethane glue has the ability to bond both porous and non porous materials and that is a very strong bond. In terms of being able to bond 2 materials together, this is a great choice to go with as the overall bond strength is quite high.

Furthermore, once polyurethane glue is totally cured, it can be sanded, stained, and painted, something else that displays just how strong and resilient it is.
Another thing to remember here is that polyurethane glue usually requires moisture to cure. Therefore, you can safely assume that once polyurethane glue is cured, it is 100% waterproof, yet another big advantage that leads to a whole lot of strength and versatility. On that same note, this specific type of glue is also UV resistant. Therefore, because it is both waterproof and UV resistant, it can be used both indoors and outdoors.

What is polyurethane glue used for

Now that you know what exactly what polyurethane glue is and how it works, let’s take a look at what it used for. The fact of the matter is that this is a very versatile type of glue that can go into virtually all materials, whether porous or non porous.


The first thing that we want to note here is that polyurethane glue is very versatile, in the sense that it has the ability to bond to very many materials. Wood, metal, stone, masonry, fiberglass, gypsum, ceramics, moldings, carpets and even some plastics can be bonded using polyurethane adhesives.

Of course, do pay attention to the fact that different types of polyurethane glue are ideal for different tasks.

Polyurethane glues come in various thicknesses or viscosities, with thicker ones being ideal for applications that require glue that won’t run all over the place and the thinner ones being ideal for applications that require a very thin layer of sealant or adhesive.

Examples of Applications

Now that you know what types of materials polyurethane glue can bond together, let’s take a look at some of the most common applications that it is used for.

  • In the auto industry, polyurethane adhesive is often used to bond windshields to the frame of the vehicle, and it is also often used in the interiors of vehicles. Polyurethane adhesives can also be used to attach wiring and other such components to the interiors of vehicles.
  • Did you know that wood chips and sawdust are mixed with polyurethane adhesive to create MDF, what we know as medium density fiberboard? Yes, this is a special type of engineered wood that we use for a whole lot of tasks.
  • Low viscosity polyurethane glue is often used to bond together various sheets of metal, and this is true for many industries.
  • Polyurethane glue makes for an excellent wood glue because it has the ability to resist moisture, UV light, and a forms a very strong bond as well. In fact, if you are looking to bond end joints of word together, then polyurethane glue is one of the best choices to consider.
  • Polyurethane glue the right type can also be used as a sealant to seal pipes, tiles, flooring and other such materials. Polyurethane makes for one of the best sealants around.
  • Due to the fact that polyurethane glue has the ability to bond ceramic together, and because once it is cured, rated food safe, it can be used to repair dishware.

Popular brands of polyurethane glue

Of course, if you expect to get the best results out of your polyurethane glue, you need to have the best glue possible. there are many popular brands of polyurethane glue out there. Some of the most popular brands of polyurethane glue that you should look out for include Gorilla Glue, E6000, Sikaflex, Tremco, and AP Products.

Fun Facts about polyurethane glue

We did our best to find some really fun facts about polyurethane glue, but the fact of the matter is that this is kind of a boring subject. While the fact that we’re about to list here are not overly fun, they’re interesting.

  • The most important thing that you need to know about this kind of glue is the fact that it is super toxic and carcinogenic when it is in its liquid form. Under no circumstances should you get that stuff on your hands, and you definitely should not ingest it either.
  • Even more interesting is the fact that although this stuff is super toxic when in its liquid form, when it is completely cured, it is 100% food contact safe. That’s quite the dichotomy to speak of.
  • Another interesting thing to note here is that polyurethane and he says are very flexible and therefore are ideal to use in applications that require impact resistance and a bit of movement capability.

How to remove polyurethane glue

How to remove polyurethane glue

One of the big advantages of polyurethane glue is the fact that it forms stretch. Such a strong bond is resistant to water and various adhesives. Well, this is also a disadvantage in the event that you get it on your skin, clothing, or anywhere else it shouldn’t be. The fact of the matter is that if you get this stuff on your hands, you absolutely want to wipe it away immediately before it drives.

If polyurethane glue dries on your hands, you’re going to have to scrape it off. Yes, people scraping glue off of your hands is going to also scrape away the skin. If you get polyurethane glue on other surfaces, try soaking it in alcohol for a few hours and then scraping it away. However, the bottom line here is that this stuff is absolutely not easy to remove.

Bad things about polyurethane glue

There are a few disadvantages to polyurethane glue that you should take note of.

  • Polyurethane glue often foams and squeezes out, which means that items being bonded together need to be clamped tightly.
  • Before this stuff is totally cured, it is extremely toxic and carcinogenic.
  • Without enough moisture present, polyurethane glue will not cure properly.
  • Polyurethane glue has a very limited shelf life, often less than one year when opened. When it is open, moisture can get in and caused the glue to set quickly.
  • Polyurethane glue is one of the hardest types of glue to remove, and it can be very messy while you are using it.


What's the best glue for polyurethane?

If you need a strong and flexible bond for elastomeric PU, Permabond 731 or 2050 adhesives are the perfect solution. For an even more versatile approach on bonding flexible polyurethane, use Permabond's specially-developed Flex CA Range which helps to preserve the flexibility of both materials - no matter how much they move!

What is the main problem with polyurethane glue?

Uncured adhesives can be susceptible to moisture, drastically reducing their shelf life. Whether 1K or 2K adhesive varieties, it's important to seek out a product with enough longevity for your specific needs – usually 3-12 months is the standard.

Is polyurethane glue stronger than epoxy?

In comparison to epoxies, polyurethanes are often softer in texture and flexibility with a lower temperature tolerance. Although they lack the strength and stiffness of their counterparts, these materials boast considerably higher elongation.

Is polyurethane glue stronger than wood glue?

When it comes to glues, Zimmerman suggests caution - polyurethane may stick well and hold unusual materials together, but yellow glue offers a bond that is truly unbreakable; with its strength surpassing even the toughest of woods.
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