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Does Hot Glue Stick To Plastic? (And Plastic Cups?)

Does Hot Glue Stick To Plastic? (And Plastic Cups?)

Whether you’re a weekend warrior or a professional crafter, there will always be moments that require you to join two pieces of plastic together. It could be as simple as attaching a broken piece back onto a child’s toy, or as complex as joining two pieces of PVC pipe.

In either case, you’ll need to know what glue type will work best for the job. And if you’re like most people, the first option that comes to mind is hot glue. After all, this adhesive is strong, versatile, and easy to use.

But does hot glue stick to plastic? Well, that’s the question we’ve heard time and again, so we decided to craft this article to help set the record straight. Keep reading to learn all there’s to know about hot glue and plastic.

Does a Hot Glue Gun Stick To Plastic

Yes, a hot glue gun can stick to plastic. In fact, plastic is one of the most common materials where hot glue does well. But it’s essential to note that not all types of plastic will work well with hot glue. As such, pay close attention to the plastic you have to ensure a strong bond.

Hot glue is undoubtedly one of the most common adhesives on the market. And for a decent reason, too. It’s relatively inexpensive, easy to find, and works on a wide range of materials – including plastic.

But again, when it comes to plastic, it’s worth mentioning that not all types of plastic will work with hot melt adhesive (HMA). But for most plastics, you can expect the product to work well and give you a bond strong enough to suffice in most applications.

Precisely, you can use hot glue on plastics such as Acrylonitrile Butadiene Styrene (ABS), Polyethylene Terephthalate (PET), PVC, and Polystyrene (PS). When applied appropriately, the glue will adhere to the surface and hold up against moderate heat and humidity.

As for some plastics like Polyethylene (PE) and Polypropylene (PP), they can be challenging to glue. In most cases, it would be best if you just opt for a different adhesive like epoxy. That way, you’ll get a more promising result.

And when using HMA on plastic, always remember that you are dealing with an adhesive that’s exactly what the name says – hot! As such, pay attention to the heat setting of your glue gun relative to the melting point of the plastic you’re working with. Otherwise, you could end up damaging the plastic.

How Strong is Hot Glue on Plastic?

How strong hot glue is on plastic will depend on the type of plastic and how well you prepare the surface before applying the glue. That could mean roughing up the surface with sandpaper to create a better grip or/and cleaning the plastic with alcohol wipes to remove any oil or dirt that could impede the bonding process.

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Generally speaking, hot glue is quite strong on plastic. But take time and ensure you’ve done everything possible to create a strong bond between the adhesive and the plastic material. Unless you prepare the surface well, you won’t get the kind of bond you need. Not even when working with plastics considered easy to glue with the adhesive.

So, remove any grease, dirt, or oil from the plastic before applying your hot melt glue. If the plastic surface is smooth, you’ll need to sand it down to create a more textured surface.

A rough surface allows the adhesive to seep in and create a better grip. That’s why the glue generally works better with porous surfaces like paper and wood. So, take time and ensure the plastic is well prepped before moving ahead with the hot glue.

How to Get Hot Glue to Stick to Plastic?

You can get hot glue to stick on plastic by preparing the plastic surface, using the right HMA for the job, and applying the adhesive at a high temperature. Each of these factors is essential to consider if you want a strong bond between the hot glue and plastic.

As for preparing the plastic surface, we’ve already said what it involves. Roughen up the surface to create crevices for the glue to seep in and remove any grease, oil, or other substance that could affect the adhesive’s ability to grip the plastic.

As for using the ideal adhesive, we recommend looking for an HMA that explicitly states it can work with the plastic. That way, you can be sure the glue will work well on the material and give you a strong bond.

We don’t mean that the regular hot glue won’t work on plastic. It will. But it might not be as strong or durable as an adhesive specifically intended for the job. So yes, search for an HMA that works with plastic and use that instead. We have lots of such online!

Finally, apply the adhesive at a high temperature. A higher temperature means the glue will flow better and penetrate the surface more easily. As a result, you’ll get a stronger bond between the hot glue and plastic.

But to forewarn you, beware that a temperature that’s too high could damage the plastic. So, always test the glue on a small area before going ahead and applying it to the entire surface. That’s a simple way to avoid any accidents.

electric-hot-glue-gun

How Long Does Hot Glue Take to Dry on Plastic?

It may take somewhere between a few seconds to 10 minutes for hot glue to dry. This variation depends on the type of glue (whether high or low temp), the type of surface, and how thick the layer of glue is. As for curing, it may take up to 24 hours, so don’t try to move or manipulate the glued surface during that time.

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On the glue type, a low-temp glue takes less time to set and cool than a high-temp one. But the latter provides a stronger bond.

On the type of surface, porous materials like wood or paper absorb glue more quickly, so the drying time is shorter. On the other hand, non-porous surfaces like plastic or glass don’t absorb glue as much. As a result, it takes longer for the adhesive to set.

Finally, the thickness of the glue layer also affects how long it takes to dry. A thicker layer will take longer to set than a thin one to dry. That’s because a thicker layer means more glue for the heat to travel through.

Is Hot Glue Permanent?

Hot glue is a relatively more permanent adhesive than most options when used in ideal conditions. It isn’t as strong as metal welds or even as some stronger adhesives like epoxy, but it can really make one heck of a bond!

You see, we can’t say that hot glue is permanent because it depends on where it is applied. As aforementioned, it binds more firmly to some surfaces than others. But on the appropriate surfaces, the bond it gives is strong enough that you shouldn’t use the adhesive if you intend to remove or separate the materials later on.

But again, keep in mind that hot melt adhesive can also be affected by temperature. Don’t get it twisted; high-temperature applications won’t melt the glue. Not even the low-temperature hot glue! However, exposing the glue to high heat can make the adhesive soften and become weak.

Hence, you shouldn’t use hot glue for tasks requiring high temperatures. If your current project will be exposed to high heat regularly, it’s best to look for an alternative that can withstand high temperatures.

The same applies when using it for black surfaces that will often be in direct sunlight. The black surface can absorb the sun’s heat, raise the temperature of the glue and potentially soften it.

Can You Use Hot Glue on Plastic Cups?

You can use hot glue on some plastic cups. But even then, if the cup you’re repairing is dishwasher-safe and has to retain that feature, go for a high-temperature hot glue like polyamide. Otherwise, you risk the adhesive not handling the temperatures in a dishwasher.

As we began by saying, not all plastics will form a good bond with hot glue. And in case the one you have will, that’s not the only factor to consider. Some cups are dishwasher-safe. Hence, to keep being dishwasher-safe, you’ll need to use a high-temp hot glue that can withstand the temperatures in a dishwasher.

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That means spending more on adhesive, which really doesn’t make sense for something like a plastic cup. In that case, it’d be best to buy a new one. After all, plastic cups only cost you a few pennies.

Alternatively, opt for other types of adhesives. But you have to know the plastic you’re using. And to tell your plastic category, check what’s written inside the recycle symbol. You’ll most likely see a number or code.

The guide below will help you know which adhesive works with which plastic.

  • Plastic classes 1, 2, 4, and 5 are the most challenging to bond. For those plastics, use adhesives that contain polypropylene or polyethylene.
  • Category 3 plastics are PVC, which we often see in plumbing. This material works best with a 2-part primer that you can obtain from most local hardware stores.
  • Plastics in category 6 are polystyrene. Use superglue or epoxy for such.
  • Plastic category 9 is ABS, which works best with some ABS solvents.
  • Category 7 plastics don’t belong to any of the classes we’ve mentioned. Examples include acrylic and polycarbonate. Super glue (cyanoacrylate) will work well for the former, while epoxy is ideal for the latter.

What Does Hot Glue Not Stick to?

Hot glue doesn’t stick to very smooth, greasy, or oily surfaces. The surface also shouldn’t be too hot or too cold. If it is, the glue won’t cure properly, and the bond won’t be as strong. You also can’t use hot adhesive on wet surfaces. The moisture will prevent the glue from sticking and curing as it should.

Some of the smooth surfaces include;

  • Glass
  • Metal
  • Plastic
  • Vinyl
  • Silicone
  • Wax

When used on such surfaces, the glue will either not stick or come off easily. But that doesn’t mean there’s no way you can use hot glue on some of these surfaces. You’ll need to create some texture or roughen the surface a bit for the adhesive to adhere well.

But for rough and non-porous surfaces hot glue works fine without the need to sand or score them. These include;

  • Paper
  • Wood
  • Styrofoam
  • Fabric
  • Cardboard
  • Ceramics
  • Organic substrates

To get the best results, clean the surface you’re planning to glue. Any dirt, grease, or debris will prevent the glue from bonding correctly. And if possible, find the hot glue specifically made for the surface you’re working on.

Final Verdict

You can use hot glue for different materials including plastics. However, it won’t form a perfect bond unless you prepare the surface or use the right type of glue. Also, not all plastics can form a good bond with hot glue. You should, therefore, check the surface you’re planning to glue to avoid any disappointments.