A lot of people are currently moving towards the use of PETG at the expense of PLA. The question here is, why? Getting a straight answer requires looking at the PETG vs PLA filament separately and drawing their differences.
Polylactic Acid (PLA) is a type of polyester plastic that most consumers prefer for 3D printing. PLA printing is considered the first step for first-timers before venturing into some more challenging materials.
On the other hand, Polyethylene terephthalate glycol-modified (PETG), has physical properties like ABS, which makes it a perfect 3D printing filament.
Both PLA and PETG filaments belong to the polyester plastics category. And like a majority of FDM 3D printing filaments, PLA and PETG are both thermoplastics. That feature means that the two materials get soft (molten) over a range of temperature and solidify upon cooling. Theoretically, this process can be repeated over and over without degrading the quality of PETG and PLA. PLA and PETG filaments are mostly available in both 1.75 mm and 2.85mm in diameter.
So how do PETG and PLA 3D printing filaments differ?
PETG vs PLA Filament
PETG and PLA are the two most commonly used 3D printing materials. At first glance, these two filaments look surprisingly similar. However, they are entirely different from almost every perspective. Let us take a look at some of these differences.
Polylactic Acid (PLA) 3D printing filament
PLA is naturally derived from cornstarch. This feature sets it aside from most materials, which are mostly oil-based, and it is, therefore, the most eco-friendly.
The first benefit of using PLA as a 3D printing material is that it is biodegradable. On the contrary, other oil-based plastics take a more extended time of up to 400 years to biodegrade and, at the same time, leave toxins in the environment. PLA takes about 60 years in the right conditions and does not leave toxic residues to the surrounding.
Based on the environmental factor, PLA filament is considerably the best material to print with. PLA is also commonly used as a 3D printing material because it is easy to use and can be printed faster than other materials. When printing plastics like ABS, the material warps considerably at the time of cooling. However, when PLA is used, such effects are reduced. Additionally, PLA can be used to print without a heated bed.
PLA Filament setting
Another benefit of using PLA as a printing material is that it does not have a bad smell when heated. Conversely, it offers resistance to its surrounding at the time of printing; at the same time, PLA filament does not soak up moisture and can, therefore, be left out for extended periods. Nonetheless, it is advisable to keep PLA filament in a sealed container. As if that is not enough, PLA filament is hard and is the most used 3D printing material if the desired outcome is intended to have no flex.
3D Printing PLA Parts
PLA parts have a crisp, well-formed look, which is a significant advantage for people looking to make beautiful models without added artifacts. Additionally, there is a wide range of PLA filaments, such as Flame retardant filament or Conductive filament.
PLA printing material does not come short of drawbacks. As much as PLA is hard, it is also brittle, and this makes products snap easily, especially if printed under strain. Another significant con is that PLA is resistant to temperature. This feature makes items printed using PLA to deform if left in direct sunlight or close to a source of heat.
Polyethylene terephthalate glycol-modified (PETG) 3D printing material
Most water bottles and other recyclable single-use plastics are made from a material called PET. PETG is closely similar to this material, but the difference is that PETG 3D printing material has added glycol to remove cloudiness and, at the same time, make the material robust but printable.
Being glycol-modified, PETG is reasonably durable and can withstand some damage because it is also flexible. The robust nature makes it more resistant to scratch and rough conditions.
3D Printing PETG items
PETG is heat resistant with a glass transition temperature of about 80 degrees Celsius. That feature makes PETG materials suitable for use in a wide range of temperatures without any deformity.
On the flip side, PETG has some slightly irritating cons. Firstly, the material is highly hygroscopic and absorbs moisture when left in damp conditions. This characteristic makes it leave unwanted texture in prints, especially when the dampness comes in contact with the hot-end. This drawback can be avoided by keeping PETG in a sealed container or drying it in an oven at 60 degrees Celsius.
Another unimpressive aspect of PETG is stringing. This situation happens when small residues (parts of plastic) are left on the print item. This can be undone by using heat or snippers to remove the hair-like materials from the print. As much as it is not a cause for alarm, stringing can reduce the overall quality of prints. Additionally, PETG leaves print surfaces with a luminous appearance hence not very attractive like PLA. The materials printed using PETG appear to have scars if the light is reflected on their surfaces.
The last aspect to look at would be the post-processing with PETG. Being a very slippery filament, PETG is not easy to post-process. For instance, painting PETG items is not natural since getting the paint to stick on the slippery surface is quite challenging. Additionally, PETG is robust and is not easy to scratch, which makes it hard to add some features that require sanding the prints. Lastly, it is hard to use some adhesives like glues and resins on PETG materials if you want to get them stuck together. However, you can maneuver around this drawback by using friction welding to merge different parts.
If your priority lies in the physical attributes of the filament, then using PETG for 3D printing will be an excellent choice. On the other hand, if you require impressive aesthetics on your prints, then PLA should be your go-to filament.
In summary, we can look at the two 3D printing filaments in the following direct comparison section.
PETG vs. PLA filament direct comparison: how to choose the right filament
In this section, the post tries to evaluate each filament based on specific qualities to help you choose the right one for 3D printing.
1. Differences in the final product
Exotic varieties of filaments like copper are only possible with PLA. As much as there are several similarities between the physical attributes of 3D printed objects in both PETG and PLA, each material has its unique features. For instance, physical strength is higher in PETG materials than in PLA materials. Conversely, PETG objects are more tolerant of high-temperature ranges and remain undamaged. Some PETG varieties like Arnie 3040 from Nexeo 3D can withstand up to 250 degrees Celsius without any deformity. However, the most common PETG materials can handle up to 80 degrees Celsius. On the other hand, PLA 3D printed parts cannot handle high temperatures and must be kept below 55 degrees Celsius to maintain their solid-state.
Use of parts
Depending on where the printed parts are to be used, you can always know the right filament to use between PETG and PLA. For instance, PETG parts are suitable for outdoor use because they are durable and can withstand high-temperature ranges than PLA parts. You can also use paints to make PLA parts more durable by protecting them from elements like direct sunlight. Transparency is also easier to achieve when using PETG filament.
Parts to be printed
If the parts you want to print are more complicated, then using PLA filament on a dual extruder 3D printer is the right choice. This is because more great support parts are available for PLA compared to PETG.
If you want exact color matching, then you should opt for PLA filaments. For instance, the Innofil PLA part matches RAL-color codes perfectly.
If you want to add more features to the final print, then PLA should be your choice. Acrylic painting, sanding, and any other post-processing work seamlessly well with PLA than PETG. You may want to test and verify the adhesion, durability, and other specifications that you want to add to the print before opting for either PLA or PETG.
PLA filaments come in wide varieties that blend comfortably. This makes it easier to mimic other materials. For instance, you can have the exact feel and look of bronze by using the Bronzeville.
Biodegradability and recycling place PLA first as it returns to the natural form when left out over time. Additionally, PLA can be recycled to produce new filaments without losing quality. Likewise, PETG is recyclable even though it does not break down easily.
The bottom line
To conclude, the choice between PETG and PLA depends on what you want to print. PLA is used extensively because it is easy to print and does not require clean-ups after the printing is done.