Best Glue for PLA – How to Glue 3D Printed Plastic

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Plastics play a large role in today’s world, and whether you are for or against plastic as a material you cannot hide from the fact that it forms an inescapable part of everyone’s everyday life. Plastics are not only ubiquitous, but can also be found in creative aspects such as 3D printing. To make the most of 3D-printed plastics, you will require the best glue for PLA. Our article will provide information on PLA adhesives and how best to use them in joining 3D printed parts.

The Importance of Plastics

You can use a number of different materials to 3D print such as metals (which include aluminum, stainless steel, titanium, and even gold) plastics, paper, resins, graphite and graphene, and powders. As you are reading this article, we can assume that you are looking to print using plastic.

Did you know that there are nine billion tons of plastic on this planet? This excessive volume of plastic consists of more than six different types. These plastics take many years to break down completely, some even as long as thousands of years. 

Although the overwhelming scale of plastic production, in conjunction with the very low rate of decomposition, has resulted in a massive problem in terms of pollution, plastic unfortunately is still one of the most convenient, and cheapest materials to use. What follows are a few aspects of plastic that make it such a popular material to use;

• Plastic is extremely lightweight
• Plastic does not conduct any electricity or heat
• Plastic has amazing durability in severe weather conditions
• Certain plastics can be extremely strong
• Plastic can be made to transport and can be made in any color imaginable
• Plastic is insoluble in water

What Is PLA?

As you can see from above, plastic in any form or shape has many positive attributes, particularly if you are looking for a durable material that offers you a variety of ways to use it and can be produced quite cheaply. One can note that while the majority of plastics take more than a lifetime to decompose, resulting in a host of problems for the environment, plastics such as Polylactic Acid (PLA) plastics solve the problem of pollution.

PLA is a form of plastic that is biodegradable and renewable. Unlike other plastics made from petroleum, which is a non-renewable resource, PLA is made from organic materials such as sugarcane and starch and is therefore biodegradable. It can take hundreds to thousands of years for petroleum-based plastics to break down, yet it only takes six months to two years for PLA plastics to break down. In addition, PLA plastic is fairly cheap to produce.

There is a variety of different kinds of PLA plastic, but they all are made from organic material. PLA’s properties are much like polystyrene (PS), Polypropylene (PP), and polyethylene (PE). It is thought of as a ‘thermoplastic’ which indicates how it reacts to heat.

You will note that PLA is used throughout everyday life in a number of contexts. PLA plastic is used to make certain bottles. Certain items utilized in the medical field as well as some food containers are made from PLA plastic (items which must be discarded once used, like some screws and plates).

It is also very popular for 3D printing users. There are four different types of plastic which are used for 3D printing, each has its own positive and negative attributes. The most popular types of plastic that are utilized for 3D printing are PLA and ABS plastic. Both of these plastics are thermoplastics, this means that once they have been heated up and their form altered while heated, and then when cooled down they solidify once again and do not lose any of their structural integrity.

Manufacturers of PLA include Corbion, WeForYou, NaturaWorks, and Evoknik. Most people prefer using ABS plastic for 3D printing, PLA offers a few superior elements which makes it the most commonly utilized plastic in 3D printing.

One of the aspects which makes PLA the superior product is that PLA needs a lower temperature for printing than ABS. Additionally PLA is able to print sharper corners than ABS plastic. A variety of colors are available in PLA plastic, as a filament for 3D printing. You can normally purchase PLA plastic as plastic pellets or a thin film as opposed to a rod or sheet stock.

As mentioned, PLA plastic needs a much lower temperature to print as opposed to ABS plastic. ABS plastic has a melting point between 392 and 500 degrees Fahrenheit (200 and 260 degrees Celsius), while PLA’s melting point is only 356 degrees Fahrenheit (180 degrees Celsius). The benefit of PLA’s lower melting point is that you will not require a closed chamber or printing bed. PLA plastic is also a lot easier to work with. Once you have finished printing PLA plastic does not require as much work as ABS plastic, the most you will need to do is a light sanding and rub down using acetone which will create smooth surfaces.

One negative aspect of PLA plastic is that the print head may potentially become clogged with PLA plastic, due to it having a higher viscosity than ABS. ABS is also more resistant and flexible than PLA plastic. Regardless of these negative elements, PLA is still the most popular choice for gluing PLA plastic pieces together.

Types of Glue

Handling the process of gluing pieces of PLA plastic together is an artform within itself. The process is underestimated by those who are new to 3D printing. Remember that joining 3D printed parts is just as important as the process of printing the pieces themselves, particularly if you are printing an item which is bigger than your printing bed.

There are many methods to glue pieces of PLA together, which include hot glue guns, superglue, epoxy, 3D pens and acetone. There is a different method of use for each of the options of bonding agent, and has its own positive and negative aspects. In this article we will provide more detail on three and provide a description of which product we feel is best on the market at present for each respective glue. First, we have outlined some considerations you will need to address to select the type of glue that will suit your 3D printing requirements.

Superglues (Cyanoacrylate)

This is a household glue that is normally used for a large assortment of applications. It is definitely one of the most popular glues in the world to be used for 3D printing. What makes it so popular? It’s affordable, dries extremely quickly, simple to use and does not leave much of a seam.

The affordability and convenience come at a price, as it is so fast drying product, you run the risk that you do not line up the pieces correctly. Worse yet, you could spill some glue on your project which would damage it! You will occasionally have to sand the surface when using superglue, which assists in joining 3D printed parts. When bonded, there is very little flexibility, as superglue is one of the most rigid glues that you can purchase. Another concern with superglue is that while the bond is extremely strong, it can become very brittle as the layer of glue is very thin which keeps your PLA piece together. Superglue should not be used if you wish for your join to be more flexible.

How to Glue PLA Using Superglue

The fast-action nature of superglue means you have to be organized before you decide to begin using it as a PLA glue for your 3D printing project. Thanks to superglue having an extremely strong bond, you need to take precautions before starting. We highly recommend you wear gloves to protect your skin and use plastic sheeting or a newspaper to protect your work surface. As you can imagine you will need to store your superglue out of reach of children.

Now that you have implemented the relevant precautions, you will have to prepare your PLA correctly. Take some fine sandpaper and use it to ensure that the surfaces you wish to stick together are even and flat. To ensure there is no dust and dirt you can use alcohol. Before you begin using glue, ensure that your surfaces are completely dry.

Keep in mind when using glue on PLA that superglue dries incredibly quickly. You will therefore need to be certain that the surfaces are correctly aligned before gluing them together. Once you have applied the glue you can then hold the surfaces together for roughly 60 seconds, and then leave the item for a few minutes to cure completely.

Best Option for Super Glue: GORILLA Super Glue Gel

This is one of our top picks when it comes to superglue, it can be utilized on an assortment of surfaces and is very effective when gluing PLA plastic together for 3D printing. This is the best glue for PLA, as it is a very quick acting bonding agent that has a consistency which is fairly thicker than standard superglue. The gel-like consistency makes it ideal for use on vertical surfaces as it will not run or drip.

The product only takes between 10 and 45 seconds to dry, meaning it is a lot more convenient than using other glues which would require you to use clamps. The product’s versatility is apparent thanks to the fact that you can apply it to an assortment of surfaces such as paper, plastic, ceramics, wood, leather and metal. The superglue is available in bottles of 0.71 fluid ounces.

GORILLA Super Glue Gel

• No run control gel formula that is great for use on vertical surfaces
• Gorilla tough anti-clog cap helps keep glue from drying out
• Specially formulated for increased impact resistance and strength

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Epoxy Resin

The next go to option for PLA adhesive is epoxy resin. A bonding agent which is very versatile that can be utilized in a number of contexts including 3D printing. After superglue this is the next best option, much like superglue epoxy creates a bond which is exceptionally strong. If your surfaces are not completely flat, meaning there are small gaps (the surfaces are not flush) you can use epoxy to fill these gaps.

So, while also being a great bonding agent, epoxy resin can also be used as a space-filler. You can also use epoxy on finished products to heighten the overall quality of the surfaces and you are even able to paint over it. If you require flexibility then unfortunately it is not the best option, though it is less rigid than superglue.

How to Glue PLA Using Epoxy Resin

You will have to put in a little more work when using epoxy resin in comparison to superglue, but the extra effort is worth it for the results. You normally receive epoxy resin in two separate containers, one holding the hardener and the other containing the resin. These two compounds will need to be combined, using the ratio that is advised in the instructions that come with the product (each brand may require different ratios). Whichever epoxy resin you purchase will come with precise instructions.

It can take anywhere from a few minutes to a couple of hours for epoxy resin to dry. Certain brands take only 5 minutes to dry. When the two components have been mixed, you will have to work quickly. Using a brand which cures slowly gives you more time to align your surfaces correctly.

Certain brands of epoxy develop high temperatures during setting and curing, which could potentially impact the PLA you are using and the 3D printer glue. You can manage the heat though by choosing a product that offers a slower (and therefore cooler) curing process.

Best Option for Epoxy: SMOOTH-ON XTC-3D: High Performance 3D Print Coating

This is a very recommended product by many customers who make use of it often. We love using it for a handful of reasons, not just because it can function as a glue, but also can be used as a coating which is smooth for any plastic surfaces.

SMOOTH-ON XTC-3D: High Performance 3D Print Coating

• Epoxy coating for smoothing 3D SLA and SLS prints
• High gloss finish will not melt plastic
• Suitable for PLA, urethane foam, wood, plaster, fabric, and paper

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3D Printing Pen

There are many positive aspects to using a 3D printing pen as glue. The pen can basically be utilized like a hot glue gun, but using PLA as opposed to glue. The great thing about the 3D printing pens is that you are able to utilize them for work which is more intricate, or if there are gaps in your surface you can use it as a filler. The 3D printing pen can be used to fill the gaps between the two surfaces or melt the two surfaces together, much like a welding tool.

Another advantage to this versatile tool is that you are able to utilize it when tackling an assortment of craft projects, not simply just gluing plastic together. Some people enjoy using them to create 3D patterns on a number of different surfaces, as an example. The main reason that we recommend these pens, is that their ease of use makes them one of the top three best means of bonding PLA.

Best Option for a Printing Pen: SCRIB3D 3D Printer Pen

This stunning pen is extremely versatile, effective, simple to use, and accurate. On top of all that it is also so much fun to use!

SCRIB3D 3D Printer Pen

• Speed control, heat monitor, safety, and anti-clogging features
• Ergonomic design for 3D drawing with 8 different speed settings
• Includes 3 colors (15 meters) of PLA plastic and stencil guide

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As noted above there are some negative aspects in comparison to the positive aspects that the 3D printer pens offer. Depending on how well you take care of the pen, and the quality of the pen you actually buy, the pens are able to last for a long time. You will naturally have to continue to purchase the PLA to refill the pen as required.

To give you a better understanding of how simple it is to use the 3D printer pens in comparison to more complicated methods of adhering plastic together, we have put together a list of steps on how one would go about using the SCRIB3D pen:

• At the back end of the pen, insert the cable
• Select the color filament you wish to use
• Switch the pen on
• Allow the pen roughly two to three minutes to warm up, when the pen is warmed sufficiently you will note a red light goes on
• In quick succession, press the ‘forward’ button twice to start
• Take the PLA filament and feed it into the back of the pen
• Once the filament has reached the front of the pen, click the ‘forward’ button. This will stop the pen from running which is ideal if you do not want a continuous flow of plastic
• Apply the PLA plastic where you wish
• When completed, press the ‘reverse’ button and hold down this will cause the filament to retract

Other Glue Types

We have provided more details on what we consider to be the top three options in terms of PLA gluing. However, when you need to glue small pieces of plastic together, there are a range of other options available, we have put together more details on a few other options.

Hot Glue Gun

A hot glue gun is an easy-to-use option to adhere to a number of different mediums. It is really good value-for-money as you can use it over and over again, from anything from plastic to wood. When selecting your hot glue gun for use with 3D printing, you can either go for a full-sized glue gun (perfect for larger projects) or a mini glue gun (recommended for beginners).

On most glue gun instruction pamphlets (much the same with most glue) you will only note a handful of words of caution. To begin with you should never use this tool in humid environments. In addition, when you have used a glue stick, you must not remove it, rather add an additional glue stick behind it, allowing the old one to be pushed forward. Under no circumstances should you disassemble your glue gun. If you have selected to use a glue gun to adhere your 3D parts together, you need to note that at any time the glue gun is receiving power, you should be working with it continuously.

The glue used in a glue gun comes in a stick form that fits perfectly into the glue gun, and is either opaque or transparent. Take note that if you want a faster-drying, rigid bond for your pieces of PLA, this particular glue is relatively flexible, and takes a fair amount of time to dry. This is one of the best options for bonding PLA due to its versatility and ease of use.

Acetone

Another option which can be used as a PLA adhesive is acetone (also known as paint thinner or nail polish remover) is utilized as a solvent in its standard use, when sticking PLA plastic pieces together, and is organic in nature.

While it is not actually a glue it dissolves the plastic to form a new bond or weld when the plastic dries again. The result is a strong bond with a near invisible join (if used correctly). This makes it worth mentioning as a possible alternative to the glues that we have already listed.

Regardless of the advantages, there are aspects which are concerning, if you do not adhere to the correct precautions when utilizing acetone. You are only able to use acetone in a well-ventilated area, if you do not follow this instruction, you may feel dizzy when working with the acetone. Acetone is also extremely flammable, so ensure to not use it near an open flame or close to heat. You also run the risk of burning through the filament should you use too much acetone.

If you wish to use acetone as a 3D printer glue, you can apply a thin layer on both surfaces, using either a cloth or a brush. How it works is that the plastic is diluted by the acetone, so they are able to mix with each other in a way that creates a new plastic as the bonding agent, as opposed to glue. Depending on how much acetone you have used, and the size of the pieces you are sticking together, your drying time will vary. It can take anywhere from several minutes to a few hours to dry, you may have to use clamps during the drying time.

Each option given in this article has its own positives and negatives when utilized for gluing PLA. Having an understanding of the relevant pros and cons can make a significant difference in terms of the longevity of your final product, and whether your gluing process will in fact be a success. We have put together a table as a quick reference, which summarizes the different gluing options for PLA plastic.

Aspects to Consider When Purchasing PLA Glue

There are several things you will have to take into consideration before selecting which glue to use, as not all glues are created equal. Take your time considering the following aspects before you make your purchasing decision.

Flexibility of the Glue

Each glue offers its own level of flexibility. Certain glues (such as superglue) are more rigid, while other options provide you with more leeway for maneuvering the different pieces of your 3D item. Think about the desired appearance and purpose of your finished product when thinking about the flexibility.

How to Prepare Your PLA Surface

Before purchasing your glue, you need to consider if you will need to sand your surfaces or not before you glue them together. For certain glues, additional friction assists the adhesion, but this is not the case for all forms of glue. This is important to determine before selecting which glue to use.

Drying Time

Each glue dries in its own setting time. Certain glues need hours or even days to dry which means you might have to use clamps. If you are working on a 3D project which you will be unable to clamp, or you just do not have access to clamps, you will require a glue with a quicker drying time. The best glue for PLA is normally a fast-drying product.

Effects of the Gluing Process

When curing, certain glues become hot. PLA may start to change shape when exposed to heat as it is sensitive to heat, or it may even melt or soften at particular temperatures that are created through the curing process. You may find that marks are created as glue can react to different substances forming the marks, or may even burn through the actual plastic.

Appearance

Certain glues leave a seam which is visible, while others leave marks, and others still need a few millimeters of glue to ensure they work correctly. This is an important aspect to consider when you are determining which glue to use, as it can impact your design in a manner that makes the item visually unappealing and impact the whole look. You ideally want a glue which is seamless and clear when working with PLA.

We hope you found this article helpful in better understanding the world of 3D printing. You now have some insight into how to glue PLA plastic together in the simplest, effective and durable manner. Whether you are experimenting with PLA plastic for 3D printing for the first time, or you have substantial experience, we hope this article will be of value to you.

Frequently Asked Questions

Can Acetone Melt PLA?

You are unable to melt pure PLA using acetone, but you can use acetone as a solvent for PLA which is utilized for 3D printing. This is due to the fact that other chemicals have been incorporated in the plastics that are used for printing, and these chemicals are impacted by the acetone.

Which Glue can be Used for 3D Printed Plastic?

You can use a number of different types of glue to adhere 3D printed plastic together. The best option is superglue to glue PLA plastic parts together (PLA is the plastic which is commonly used for 3D printing) as it is an affordable, fast-drying, and strong adhesive. Keep in mind superglue is not very durable as it is relatively brittle.

Can Gorilla Glue be Used on PLA?

Yes, Gorilla Glue works perfectly as a glue for PLA plastics when they are utilized as filaments for 3D printing. A lot of people choose to use Gorilla superglue due to its thick consistency making it unlikely to drip and is normally simple to work with.

How to Glue PLA Plastic?

There are a number of glues which will work, which one you select is dependent on your requirements and preference. Your options include acetone, plumber’s cement, hot glue, 3D printing pens, and superglue. Each form of glue uses its own application process, and has its own unique drying time, and other elements that could impact the appearance of your 3D piece and your overall experience.

Can I Use Hot Glue to Glue PLA Together?

Yes, you are able to work with hot glue on PLA plastic. Remember that the glue has to reach a certain temperature to melt it, and it is likely that your PLA may become deformed as a result of the heat from the gluing process. Hot glue takes time to dry and is relatively flexible, but this is dependent on which brand you use.