Polylactic acid (PLA) is the most widely used thermoplastic in extrusion 3D printing. If you’ve ever used an FDM 3D printer, chances are you’ve fed a spool of regular PLA filament through it. That’s because PLA is cheap, biodegradable, and melts at a conveniently low printing temperature.

But although PLA has many advantages, standard PLA filament doesn’t perform to a high enough standard for many serious applications. It absorbs lots of moisture from the air, and its low melting point makes it unsuitable for high-temperature applications (in machinery, for instance). It also exhibits brittleness and can shatter when subjected to strong forces.

The limitations of normal PLA mean that users of FDM 3D printers often choose other commodity polymers like ABS (or engineering plastics such as POM or PETG) when they need to make an end-use part or functional prototype. However, there’s another option that retains the benefits of PLA while mitigating some of its flaws.

PLA+ is a family of “enhanced” PLA filaments comparable in price to ordinary PLA but with slightly better material characteristics. But what exactly is it, and is it worth buying over regular PLA filament?

What is PLA+?

esun The eSun PLA+ filament is popular with hobbyists (credit: eSun)

Before we can understand what PLA+ is, we need to understand what it isn’t, and we can do this by comparing it to regular PLA.

Polylactic acid (PLA) is a scientific term for a material made from fermented plant starch (such as corn or sugar cane) that is defined by a specific chemical formula.[1] PLA+, on the other hand, is not a scientific term; it is a marketing term used by material developers to identify a PLA filament that has been modified to perform better. The same goes for terms like PLA Plus, PLA Pro, Engineering PLA, Tough PLA, and Enhanced PLA.

In other words, while PLA+ always contains standard PLA as its base, those “plus” elements can be virtually anything: fillers, pigments, nucleating agents, small quantities of other thermoplastics, or other modifiers.

Many PLA filaments contain calcium carbonate-based additives which can alter the mechanical performance of the filament.[2] Examples of PLA-based filaments enhanced with additives include eSun PLA+, which contains 2% calcium carbonate, and Polymaker PolyMAX PLA, which contains acrylic polymers. On the other hand, PLA+ filament doesn’t necessarily need to contain any additives at all. A company’s “PLA+” product might simply be ordinary PLA processed in a special way that results in good performance.

Unfortunately, lots of material developers do not stipulate the exact chemical composition of their PLA+. But this doesn’t mean that PLA+ is just a gimmick: in many cases, PLA+ does indeed outperform PLA in areas such as layer adhesion and toughness — we just can’t always say why.

There are plenty of PLA+ filaments on the market, though manufacturers do not always use the term “PLA+” to refer to their modified PLA formulations. Products in the PLA+ category include:

eSUN PLA+
Polymaker PolyMAX PLA
Duramic 3D PLA Plus
Overture PLA Professional
Filamentive Tough PLA
Jayo PLA+

Due to its low price on platforms like Amazon, the eSUN filament has become especially popular.

Finally, it is important to draw a distinction between PLA+ (which is a “tweaked” filament composed almost entirely of PLA) and PLA-based composites. Composites also contain extra ingredients — reinforcing chopped fibers, for instance — but typically in larger quantities, sometimes around 50%. Composites are more expensive than PLA+ and often have engineering applications. Examples of PLA composites include 3DXTech’s CarbonX PLA+CF (a composite of Natureworks PLA and premium high-modulus carbon fiber) and Protopasta’s Iron-filled Metal Composite PLA (a composite of PLA and iron).

PLA vs PLA+: What are the Differences?

Because some manufacturers don’t tell us exactly what they put in their PLA+ filament, we can’t really say how PLA and PLA+ differ in terms of their content. However, we can compare PLA and PLA+ in terms of material performance and other characteristics.

Even taking into account variations between different brands of PLA+, there are several notable differences in material performance between regular PLA and PLA+. For instance, PLA+ tends to provide better layer adhesion, toughness, and surface quality, but it may be less convenient than PLA due to its higher printing temperature (making it harder to print on non-heated build plates with a low bed temperature). Depending on the brand, PLA+ may also be slightly more expensive than PLA and is generally available in fewer colors.

The main differences between PLA and PLA+ are explained in the following sections, giving an indication of which material is best in certain situations.

Strength and Toughness

Despite its low price, normal PLA is a fairly strong 3D printer filament. It is stronger than ABS, for example, although it also has a high level of stiffness and brittleness.

The brittle nature of PLA makes it unsuitable for demanding applications. It has poor impact resistance and tends to shatter into pieces when it breaks, making it a potential safety hazard.

PLA+ is stronger and more rigid than standard PLA, as well as having a higher level of toughness. Chinese filament company eSUN, one of the main filament brands making PLA+, claims its PLA+ is twice as tough as typical PLA filament, while Filamentive says its Tough PLA has an impact resistance of 29.8 kJ/m² (compared to 3.4 kJ/m² for normal PLA).

Flexibility

PLA+ is usually more flexible than standard PLA, with users of PLA+ filament reporting good ductility of printed parts compared to those printed with regular PLA. PLA+ can therefore be seen as occupying a kind of middle ground between PLA and ABS.

One example of a flexible PLA+ is Sunlu PLA+, a cheap and widely available product that has an elongation at break of 45%. Ordinary PLA typically has an elongation at break of just 5–7%, while the figure for ABS ranges between 10–50%.[3]

Temperature Resistance

One of the biggest drawbacks of standard PLA filament is its susceptibility to deformation at higher temperatures. Its temperature resistance is very poor compared to other common 3D printing materials like ABS.

Because of this, developers of PLA+ have attempted to tweak the common filament into being more resistant to higher temperatures, allowing FFF 3D printer users to make functional parts designed for use in hot environments.

But a drawback of this higher temperature resistance is a higher required printing temperature. The eSun PLA+ has a suggested print temperature of 205–225 °C, around 15 °C higher than the company recommends for standard PLA.

Ease of Printing

Ease of printing is closely related to temperature resistance, and PLA+ can be regarded as harder to print than PLA if using a beginner-level FDM printer that doesn’t perform well at the slightly higher temperature required.

The difficulty with PLA+ is compounded if a 3D printer does not have a heated print bed/build plate. Print bed adhesion (first layer adhesion) is typically worse with PLA+ than standard PLA due to its higher temperature resistance, and problems will be more severe if using a non-heated build plate. The higher temperatures involved with PLA+ can also contribute to increased warping.

The lower viscosity of PLA+ compared to PLA makes it more likely to cause clogging as it passes through the extruder and nozzle, while users of PLA+ filament have also reported occasional issues with stringing.

Surface Quality

Manufacturers offering PLA+ filament tend to market their product as a high-quality version of PLA, promising a good surface finish on printed parts. eSun says its PLA+ material has “good glossiness.”

Although there is no clear reason why PLA+ offers this advantage, users often agree that PLA+ can provide a smoother finish than standard PLA.

Post-Processing

PLA and PLA+ offer similar post-processing options, with some types of PLA+ potentially providing advantages in terms of sanding and gluing due to its improved mechanical properties. Both materials can be sanded, painted, and glued, among other post-processing options.

Color

different-colors-pla_plus Color variations of PLA

Enhanced PLA filaments can be colored with pigments, as with standard PLA. However, the limited number of material developers offering a PLA+ product range means that there are fewer color options for PLA+ than there are for PLA. There are also very few transparent filament options for PLA+.

Note that the introduction of pigments can affect the mechanical properties of a thermoplastic.[4] Because of this, manufacturers of PLA+ may avoid certain pigments that negatively affect properties like strength and temperature resistance.

Storage

Both PLA and PLA+ should be stored in a way that prevents moisture absorption. Both filaments can benefit from being stored in vacuum-sealed bags, while dedicated filament drying machines — used before or during printing — can result in superior performance.

Environment

One of the advantages of both PLA and PLA+ is their biodegradability, which makes them slightly more environmentally friendly than petroleum-based plastics. PLA is derived from renewable resources, such as corn starch and sugarcane, and can be biodegraded under specific conditions, typically with high humidity, elevated temperatures, and the presence of microorganisms.

The additives and modifiers present in PLA+ do not significantly affect its biodegradability, as they are typically present in small amounts and are designed to be compatible with the base PLA material.

Although PLA and PLA+ are not easily recyclable like some other plastics, they can be recycled to some extent. Some recycling facilities accept PLA and PLA+ waste, where they can be processed and turned into new products such as agricultural mulch. However, a better use for scrap prints is to turn them back into filament using a machine like a Filastruder.

Price

As a rule, material manufacturers that sell both PLA and PLA+ filament typically put a slightly higher price on PLA+, as it is supposed to offer better performance and print quality. On Amazon, eSun PLA+ costs around $26/kg, while the same company’s regular PLA filament costs around $23/kg.

Using eSun as an example, the price difference between PLA and PLA+ is clearly quite small. Furthermore, premium-brand “standard” PLA can often cost more than budget-brand PLA+. For instance, Makerbot’s high-quality METHOD PLA filament costs around $86/kg, far more than eSun PLA+.

Applications of PLA and PLA+

Models 3D printed in eSun PLA+ (credit: eSun)

The small differences between PLA and PLA+ make for a slightly different set of possible applications for the materials. While both materials are typically used for low-cost prototyping rather than critical parts, some PLA+ prints can handle fractionally more demanding applications.

PLA	PLA+
Visual prototypes and models in a very wide range of colors	Visual prototypes and models with excellent surface appearance
Functional parts to be used at room temperature with low flexibility requirements	Functional parts to be used at moderately elevated temperatures and/or with moderate load-bearing requirements

Conclusion

Material developers market their PLA+ filament as a high-quality version of PLA that produces some advantages over the standard version of the filament. As we have seen, PLA+ usually delivers on those promises, offering superior toughness and layer adhesion, as well as other benefits. Thousands of 3D printer users have reported positive results using common PLA+ filament brands like eSun and Overture, proving that these materials can work well under the right printing conditions.

However, we should also remember that the term “PLA+” is not a guarantee of quality, and a standard PLA from a trusted filament brand will often outperform a PLA+ from an unknown or unreliable seller.

Furthermore, while the material characteristics of PLA+ may be suitable for certain 3D printing projects — printing parts to be used in high-temperature environments, for example, or parts that require a high level of impact resistance — they may be unsuitable for others. For instance, FFF printers that lack high-temperature capabilities (or that do not have heated beds) may be better suited to printing standard PLA, which has a low melting point and is easy to print.

Finally, buyers of FFF filament should remember that neither PLA nor PLA+ are particularly high-performing thermoplastics, and they are more often used for prototyping than functional parts. If a 3D printed part will be subject to high levels of stress, it may be better to use an engineering plastic like POM or nylon, or even a high-performance plastic like PEEK, rather than opting for the marginal gains offered by PLA+. In other words, while PLA Plus filament can make PLA parts better, it cannot perform miracles.

Frequently Asked Questions

Can PLA and PLA+ be used interchangeably in a 3D printer?

Yes, both PLA and PLA+ can be used in most 3D printers that support PLA filaments. However, PLA+ may require slightly higher printing temperatures and bed temperatures compared to standard PLA. It is essential to follow the manufacturer's recommendations and adjust the settings accordingly.

Is PLA+ food-safe?

The food safety of PLA+ depends on the specific formulation and additives used in the material. Some PLA+ filaments may be considered food-safe, but it is important to check with the manufacturer to confirm. Additionally, 3D printed objects may have small crevices where bacteria can grow, making them unsuitable for direct food contact without proper post-processing and sealing.

Can I mix PLA and PLA+ in a single print?

While it is technically possible to mix PLA and PLA+ in a single print using a dual extruder 3D printer, it is essential to ensure that the materials are compatible and have similar printing temperature ranges. Moreover, there would be few obvious benefits to mixing these two materials, as they are very similar to one another. Mixing materials can also introduce challenges in terms of layer adhesion and surface finish.

How do I store PLA and PLA+ filaments?

Both PLA and PLA+ filaments should be stored in a cool, dry place away from direct sunlight. It is recommended to use airtight containers with desiccant packs to prevent moisture absorption, which can affect print quality and performance.

Can I use the same slicer settings for PLA and PLA+?

While PLA and PLA+ share many similarities, PLA+ may require slightly different slicer settings, such as higher printing temperatures and bed temperatures. It is essential to fine-tune the settings based on the specific material and follow the manufacturer's recommendations for optimal results.

References

[1] Humphreys R. From Corn to Poly Lactic Acid (PLA): Fermentation in Action [Internet]. Polymer Innovation Blog. Innocentrix, LLC; 2012 [cited 2021Dec19].

[2] Cuiffo MA, Snyder J, Elliott AM, Romero N, Kannan S, Halada GP. Impact of the fused deposition (FDM) printing process on polylactic acid (PLA) chemistry and structure. Applied Sciences. 2017;7(6):579.

[3] Elongation at Break or Fracture Strain: Technical Properties of Plastics [Internet]. Omnexus. SpecialChem; [cited 2021Dec19].

[4] Soares JB, Finamor J, Silva FP, Roldo L, Cândido LH. Analysis of the influence of polylactic acid (PLA) colour on FDM 3D printing temperature and part finishing. Rapid Prototyping Journal. 2018 Nov 12.

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