PLA vs. ABS: Which One Should You Use?

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Although 3D printing hobbyists and professionals nowadays are spoiled when it comes to filament choices, there are two that will always come on top: PLA and ABS. These standard filaments pretty much formed the foundation of more fancy filament options, and they remain in wide use until today. They are accessible, cheap, and easy to work with.

Practically anyone who has ever dabbled with 3D printing has spools of both ABS and PLA lying around. In case you’re wondering if it’s best to print your next big project with ABS or PLA, then check out our rundown of the benefits and limitations of both filament materials.

What is PLA?

PLA is short for Polylactic Acid. As its name implies, PLA is a polymer made of lactic acid building blocks. It was first synthesized back in 1932, although only a low-density version was possible back then. By using lactide instead of lactic acid as raw material, the polymerization process for PLA was highly improved and yielded the high-density version that we know today.

When broken down, PLA produces lactic acid. This is a compound that can be safely absorbed by the human body and in the environment, making PLA a fully biodegradable and bioactive compound. Due to the nature of its interaction with the human body, PLA has been extensively used in the medical field for sutures and stents.

Nowadays, PLA is considered as one of the major alternatives to traditional non-sustainable plastics. Because it’s fully compostable, it addresses our solid waste problem while also reducing our dependency on petroleum-based products. Large-scale applications of PLA have risen in the past few decades, making it the second highest bioplastic in terms of worldwide rate of production.

Benefits of PLA

1. Sustainable manufacturing

Sustainability is a hallmark of PLA as a manufacturing material. Its lactic acid component is mainly derived from plant material. The natural carbohydrate content of any plant material can be processed by bacteria to produce lactic acid through fermentation. Nowadays, PLA is typically produced from corn starch, cassava roots, or sugarcane. All these crops can be harvested several months after planting, making PLA manufacturing highly sustainable and renewable.

2. Fully biodegradable

As we’ve mentioned before, PLA breaks down biologically into lactic acid. In turn, lactic acid can be absorbed by the body or by the environment with little consequence. This does not mean that they can be disposed of anywhere. You’ll still need to send your scrap PLA to a composting facility which can dispose of it the proper way.

You’ll also need to be careful of PLA filaments that may have been treated with dyes. Some of these dyes are non-biodegradable, especially petroleum-based ones. Before disposing of your scrap PLA prints, make sure that it is really biodegradable.

3. Low printing temperature

PLA prints at a relatively low temperature range of 150 to 160 °C. Not only does this make the printing process less power-intensive, but it also helps avoid some of the most common problem encountered in 3D printing. Moreover, a heated printing bed and a cooling fan are not absolutely necessary when printing with PLA.

4. Easy to work with

The fact that PLA prints at a low temperature means that it is one of the easiest filaments to work with. Since it cools at a gradual rate, it does not run into warping problems. This is mainly the reason why PLA does not need a heated printing bed, although you may still need to use an adhesive aid such as blue painters’ tape.

Stringing is another issue that can be avoided with PLA, as it only typically happens in high-temperature 3D printing. Stringing occurs when the melted filament continues to drip down from the nozzle as the nozzle head moves from one point of the print to another. The result is a mess of filament ‘strings’ that all but render a print unusable.

You also won’t need to worry about the smell when printing with PLA, as it produces no toxic fumes. It can still emit microparticles during the printing process, so we still recommend that print in an area with good air circulation. Or you can just open a window.

Limitations of PLA

1. Not appropriate for high-temperature applications

Since PLA prints at low temperatures, it can also easily degrade when exposed to extreme heat. This means that raw PLA cannot be used to create prints meant to hold hot food or beverages. Even leaving a PLA print inside your car on a hot day can turn it into a puddle of melted plastic.

2. Lacks durability

PLA is not known for durability. PLA prints are brittle and tend to quickly degrade when exposed to sunlight and other outdoor elements. If you’re printing a pot for your outdoor plant, then PLA is going to be a very bad filament choice. PLA is great for making rapid prototypes or display items, but it’s not a material we would use for functional parts.

What is ABS?

ABS is short for acrylonitrile butadiene styrene. It is a terpolymer or a polymer that is made of three different monomers. These three monomers are easy to guess from the name – acrylonitrile, butadiene, and styrene. Each one of these monomers imparts a physical property to ABS that makes it a structurally excellent material. Acrylonitrile provides chemical and thermal stability, butadiene provides durability and impact strength, and styrene gives the material a smooth and glossy finish.

These three monomers can be mixed in different proportions according to which physical property is going to be prioritized by the manufacturer. ABS has also been combined with other monomers to create composite polymers such as polysulfonates and polycarbonates. These composite blends have been used in a range of commercial and industrial applications.

First synthesized in the 1950s, ABS was considered a superior alternative to standard synthetic rubber. In a few years, ABS became a highly valued engineering polymer due to its superior physical properties, the versatility of copolymers, and ease of processing. Today, ABS is one of the highest-selling engineering thermoplastics.

Benefits of ABS

1. Durable

Compared to PLA, ABS exhibits much higher impact resistance and toughness. It is the more suitable filament material for 3D printing parts that you expect will undergo a lot of wear and tear. If you’re printing functional parts such as hinges and brackets, then ABS is a much better choice than PLA.

ABS is also much more chemically resistant, making it less prone to degrade when exposed to UV radiation. If you have to choose between PLA and ABS for printing an item to be used outdoors, then you’d probably be better off with ABS.

2. High-temperature resistance

ABS prints at a much higher temperature between 220 to 250 °C. While this makes the printing process more power-intensive and introduces a lot of printing challenges, it also gives ABS prints a much higher level of heat resistance. Again, this characteristic makes ABS the preferred filament materials for outdoor items, since these are more likely to be exposed to extreme heat.

While ABS can theoretically withstand the temperature of hot food and liquids, ABS is generally not recommended for making food containers. We’ll go into more detail on this later, but ABS does tend to release toxic compounds, especially when exposed to heat.

3. Better finishing options

ABS is soluble in acetone, and this simple fact has far-reaching advantages. The first is that ABS can be melted in acetone to come with an “ABS Glue,” an adhesive that can be applied on the build platform to avoid warping problems when printing with ABS.

The more important result of this characteristic is that acetone can be used to dissolve a very thin layer on the outer surface of an ABS print, effectively giving it a smooth and uniform finish. The best way to achieve this is to give the ABS print an acetone vapor bath. It hardly takes any effort, and when done right, can result in a perfectly smooth finish that will take a lot of work to be replicated with PLA.

Limitations of ABS

1. Derived from petroleum sources

In stark contrast to PLA, all three basic monomers of ABS are hydrocarbons that are derived from petroleum products. This makes ABS not any better than any traditional plastic product in that it’s non-sustainable and contributes to the planet’s growing solid waste problem. With more and more consumers gravitating towards more environment-friendly options, it may only be a matter of time before ABS completely falls out of favor.

2. Difficult to print with

ABS isn’t the type of filament material that beginners should be working with. Due to its high printing temperature, ABS is particularly prone to warping. This happens when a printed layer cools down unevenly, typically resulting in the corners of the first layer of the print lifting off the build platform. Moreover, warping can result in distortion of individual parts of a print. This distortion may be barely noticeable at times but is not ideal when prints need to be intricately detailed and measured.

There are a couple of ways that you can avoid the warping problem, and you’ll probably need a combination of two or three of these methods to get good results. A heated printing bed is practically a necessity when printing with ABS, as is a good bed adhesion method. More than just turning off your cooling fan over the whole printing process, you might even need to install a bed enclosure to slow down the cooling process of the print.

Stringing is another problem that you’re bound to encounter when printing at high temperatures. You might just need to adjust your slicer settings or enable retraction to avoid stringing, so this is an easier problem to solve than warping.

3. Produces toxic fumes while printing

When exposed to heat, ABS can release styrene, which is a known carcinogen. 3D printing with ABS in an enclosed space can increase the concentration above the recommended threshold. It is for this reason that a well-ventilated space is needed when printing with ABS, and also why ABS isn’t recommended as a food or drink container.

Fortunately, newer 3D printers come with an integrated HEPA filter that can remove the noxious components of the fumes emitted during printing. While this helps make the fumes less irritating, there’s no guarantee that the filtered air completely safe to inhale for long periods. We still recommend cracking open a window or better yet, printing with ABS in a wide open space.

Which filament should you use?

It’s easy to see how both ABS and PLA have remained relevant in the world of 3D printing. They each have merits that make them very good options for 3D printing common objects such as display items, prototypes, and replacement functional parts. To help you decide which filament is better for your upcoming project, then here’s a quick selection guide.

1. Print with PLA if…

• You’re a beginner

With all the slicer settings adjustments and printer tweaks you need to do to avoid all the problems with ABS, we really wouldn’t recommend it for someone who’s still a beginner in 3D printing. PLA is a much simpler material that barely has any learning curve.

• You don’t have a heated printing bed

If you don’t have a heated printing bed, then you likely won’t get good results when printing with ABS or any other high-temperature filament. Bed adhesion methods, such as painters’ tape or ABS glue, won’t be enough.

• Accurate details and dimensions are important

ABS is so prone to warping that important details and dimensions will probably be altered from the design to the actual print, even without you noticing. Since PLA has no warping issues, it can better preserve the original design without distortions.

• You want to make the environment-friendly choice

This may sound like pandering, but there’s a growing consciousness for more environment-friendly choices within the 3D printing community. If you are concerned about reducing solid waste and our dependency on non-sustainable fuel-derived sources, then PLA is absolutely the best option for you.

2. Print with ABS if…

• Your print needs durability, impact resistance, and heat resistance

What ABS lacks in being sustainable, it makes up for with superior physical and chemical characteristics. If you are printing an item that will undergo heavy wear and tear, regular or sustained impact, exposure to high temperatures, and exposure to outdoor elements, then you really need to stick with ABS.s

• You want a print with a professional-grade finish

Post-processing a PLA print to get a smooth finish requires a lot of sanding and polishing – basically pure elbow grease. Finishing an ABS print requires just a fraction of this effort by doing an acetone vapor bath. Not only is this process faster and easier, but it also results in a smoother and more uniform finish. If you want your print to come out looking like a professional did it, then ABS is the more practical option.

Final thoughts

PLA and ABS are considered to be the building blocks for the more complex and fancy filaments that seem to have become trendy in the field of 3D printing. Although they are quite basic and aren’t so flashy, they remain relevant because they are reliable and easy to use.

Another factor for why most 3D printing professionals typically have PLA and ABS spools lying around is because they are very cheap. A 1-kilogram spool of either filament will set you back by a mere $20, and this is probably enough for several dozen small prints.

Right now, the trend of consumer behavior seems to be moving towards more environment-friendly options. This is the reason why PLA has overtaken ABS as the most commonly used 3D printing filament. ABS probably isn’t going anywhere, though – at least not in the near future.

Warning; 3D printers should never be left unattended. They can pose a firesafety hazard.