PLA vs PETG: Which Filament Should You Choose?

Two popular FDM filament materials are PLA (Polylactic Acid) and PETG (Polyethylene Terephthalate Glycol). Both filaments are similarly priced but have unique characteristics that make them better suited to different printing projects.

You might be wondering which is better for your print. How should you choose? What should you consider?

Let’s explore what makes each material unique and help you better understand which filament you should choose for your project.

PLA vs PETG Overview

Hobbyists and rapid prototyping commonly use PLA, while PETG is primarily used in food-safe applications and objects that require high strength and durability.

PLA is an easy-to-use filament with a low melting point, good surface finishes, and compatibility with most 3D printers. Its high print quality, ease of use, and compatibility with most printers make it an excellent choice for beginners.

Raw PLA plastic is derived from crops like corn and sugar cane. The starch from these crops is extracted and mixed with special chemicals, which are then fermented and condensed or polymerized to create raw PLA plastic.

PLA is often described as biodegradable. Although it is true that PLA is biodegradable, it only biodegrades under industrial composting conditions. The filament may be biodegradable in nature but over a long time.

PLA filament has several downsides, including its brittleness, low durability, and unsuitability for high-heat environments. High temperatures and UV rays cause discoloration, warping, and shrinking making PLA prints unsuitable for outdoor use.

PETG is an oil-based polymer that offers higher strength, flexibility, and impact resistance than PLA. PETG comes from the popular PET plastic found in water bottles. The added “G” in PETG stands for glycol, which reduces the melting temperature, making it suitable for printing.

While PETG is 100% recyclable, it is not biodegradable like PLA. 

The filament produces better, more durable, and longer-lasting parts than PLA. PETG is also resistant to high temperatures, UV rays, chemical solvents, and water. 

But PETG is much harder to work with compared to PLA, which makes it not suitable for beginners. It also requires a higher nozzle temperature and isn’t compatible with as many printers as PLA.

Material Comparison

Temperature Settings

PLA requires a relatively low nozzle temperature between 190°C and 220°C and a bed temperature of around 60°C. PETG, on the other hand, requires a slightly higher print temperature, ranging from 220°C to 250°C, and a bed temperature of 75°C.

You want to make sure to set the right nozzle temperature because if it is too hot, you may have more noticeable layer lines, and too cold may result in nozzle clogs and layer adhesion issues.

I often find that Bowden-style printers benefit from staying at the lower end of the nozzle temperature range. Lower temperatures help reduce stringing and blobs, especially when printing PETG.

The last thing I notice is where you place your printer will have a big impact on the printing temperature. 3D printers placed in colder environments require hotter nozzle temperatures than a printer in warmer climates.

Bed Adhesion

Bed adhesion plays a vital role in the success of your 3D prints. If the part doesn’t stick to the print bed, then you’ll end up with a bird’s nest.

In my experience, I find that both PLA and PETG have good bed adhesion properties. I don’t have trouble with either filament sticking to the build surface.

However, PLA has better bed adhesion. It’s far more forgiving and requires less tuning to get a good stick.

I find that with PLA, I can be a bit lazy and don’t need to aggressively clean my build plate before each print. It’s very rare that I need to use adhesives or painter’s tape to help with bed adhesion.

PETG has good surface adhesion but is a bit less forgiving. It’s important to ensure you clean the build plate before printing with PETG. It also helps to use a glue stick or painter’s tape if you’re struggling to get your prints to stick.

Print Quality

PLA is regarded for its excellent print quality. The filament is easy to work with, and you can often achieve excellent results with the default profiles found in your slicing software.

PETG is considered to be an easy-to-use filament. However, many people find issues with stringing which impacts the finished print quality. You can fix PETG stringing by adjusting the retraction settings.

PETG requires much more calibration and tuning to achieve excellent results. But even if you dial in your slicer settings, PETG can’t match the print quality of PLA.

Post-Processing

Post-printing treatments can significantly enhance the aesthetics and functionality of your 3D-printed objects.

I’ve found that PETG and PLA respond well to post-processing. Both 3D printing filaments are easy to sand, fill, and paint. Though PLA sands a bit easier as it’s a softer plastic.

Be very careful when using an electric sander or dremel on PLA parts. The heat generated by the friction of electric sanding tools can melt the plastic if you aren’t careful. If you use an electric sander, go slow and give time between passes for the printed part to cool down.

Melting PETG is still a concern when using electric tools. But PETG’s higher melting point makes it less likely to melt or deform.

Post-processing treatments like sanding, priming, and painting can increase the smoothness of your prints. But at the cost of losing fine details.

Removing support structures is an essential part of post-processing your 3D prints. Because PLA has weaker layer-to-layer adhesion, support structures are easier to remove.

Chemical Properties and Composition

PLA Composition

PLA, or Polylactic Acid, is a thermoplastic derived from lactic acid formed by the fermentation of plant starch. It is a biodegradable and renewable polyester that is mainly produced from corn starch, tapioca roots, and sugarcane.

PLA is the most common 3D printing filament. The budget-friendly filament is available in a wide range of colors.

Specialty PLA filaments also have carbon fiber, wood, and other materials incorporated into them to help improve their mechanical properties and add additional aesthetic properties.

Here are some of its key properties:

• Melting temperature: ~170°C to 180°C
• Glass transition temperature: ~60°C to 65°C
• Mechanical Properties: Lower strength and flexibility compared to PETG

PETG Composition

PETG, or Polyethylene Terephthalate Glycol-modified, is a form of Polyethylene Terephthalate that contains glycol. The glycol lowers the material’s melting point so that it’s usable with hobby-level 3D printing machines.

PETG is a durable and versatile thermoplastic, offering higher impact resistance and flexibility than PLA. PETG filaments have a clear and glossy appearance. The 3D printer filament is available in a variety of colors, including transparent and translucent options.

Here are some of its key properties:

• Melting temperature: ~220°C to 250°C
• Glass transition temperature: ~80°C
• Mechanical properties: Greater heat, impact, and chemical resistance compared to PLA

Physical and Mechanical Properties

Strength and Durability

When comparing PETG and PLA, it is important to note their strength and durability, as this is where they differ greatly.

PETG is generally more impact-resistant than PLA, giving it an edge in terms of durability. It also boasts greater flexibility and better layer-to-layer bonding.

Both materials offer solid tensile strength, but PETG is more suited to parts that require higher heat and impact strength.

Both PLA and PETG are hygroscopic, meaning they absorb moisture from the environment over time. Both 3D printer filaments will lose their physical and mechanical properties if they are not stored correctly.

Warping and Shrinking

Having dimensional stability could be very important for some prints. For warping, I find that both PLA and PETG will print similarly and are quite dimensionally stable.

You shouldn’t run into any issues with warping or shrinking while printing, as long as you use the correct bed temperature.

However, I’ve noticed that PLA-printed parts are susceptible to warping warm temperatures, especially dark-colored filaments.

Thermal warpage is less of a concern for PETG because of the increased melting temperature. Therefore, PETG is much better for outdoor applications or parts that require heat resistance.

Stringing and Layer Adhesion

Stringing is a common concern when 3D printing. PLA generally exhibits less stringing than PETG, making it ideal for designs with intricate details and overhangs.

PETG stringing is a common issue. By carefully tuning your slicing settings, you can eliminate strings from your prints.

PETG provides much better layer adhesion, creating layer bonds that won’t break as easily as PLA.

Cost Comparison

Both 3D printing materials are affordable options, but PETG is slightly more expensive than PLA.

PLA is generally more affordable, with prices starting at $17 per spool of 1kg filament, while PETG prices start at around $20. Though prices vary depending on the brand and quality of the filament.

If you need stronger prints and don’t mind sacrificing print quality, the price difference is negligible.

Which Filament to Chose

Choose PLA for projects that don’t require high strength or durability. It’s an excellent choice for hobbyists and beginners because of its ease of printing and provides better surface finishes. PLA filament is available in a wide color range and finishes. The low shrinkage and warping make it suitable for producing decorative items, prototypes, and non-functional models. However, due to its low heat resistance, PLA is not suitable for outdoor use or 3D printing applications that come in contact with high temperatures.

Choose PETG if you are making parts with higher strength and temperature requirements. PETG is perfect for functional parts or components. With its stronger impact resistance and chemical stability, PETG is an ideal material for producing enclosures, mechanical parts, and automotive components. It can withstand moisture and offers better UV resistance than PLA, making it well-suited for outdoor use. However, the higher learning curve makes it a bad choice for beginners.