ABS vs. PETG: A Head-to-Head Comparison
ABS has been a staple of the 3D printing industry. It’s very durable, heat-resistant, inexpensive, and easily available. However, a relatively newer filament has proved to be a formidable challenger in terms of strength and heat stability. The new kid on the block, called PETG, has quietly made its way to being one of the most popular filament materials today, next only to ABS and PLA.
How do ABS and PETG compare side-by-side? Is there a reason to choose one over the other? Check out the detailed comparison below.
What is ABS?
ABS stands for Acetonitrile Butadiene Styrene, a terpolymer made of three different monomers. Each of these three monomers – acetonitrile, butadiene, and styrene – contribute a critical element that determines the physical and chemical properties of ABS. These three monomers can also be mixed at different proportions which control which of the properties are most prevalent. With a unique combination of thermal stability, durability, and a glossy finish, ABS has quickly become one of the most widely used filament materials in 3D printing.
The versatility of ABS has also made it a valuable engineering polymer. Composite polymers made using ABS as a base have been used in a wide range of industrial and commercial applications. From its humble beginnings as a viable replacement to rubber, ABS is now one of the highest-selling engineering thermoplastics.
Advantages of ABS
1. Higher temperature resistance
ABS prints at a temperature range of 220 to 250 °C, which easily one of the highest temperature ranges needed for D printing. Although this makes printing with ABS very energy-intensive (and presents a few challenges in the printing process), it also makes ABS prints remarkably stable when exposed to heat. This has made ABS an ideal material for items that are frequently exposed to high temperatures such as the dashboard and seats of a car, or pipes and fittings for hot liquids.
2. Cheaper
In terms of manufacturing costs, ABS isn’t that much cheaper than PETG. However, ABS is much more widely used and more easily available. You can easily find cheap spools of ABS filament simply because of the abundance of similar products.
3. Better post-processing options
The compatibility of ABS with acetone as a solvent is one of its more unique characteristics. Not only is it possible to make an ABS glue by dissolving ABS in acetone, but acetone can also be used to smooth an ABS print. A technique called an acetone vapor bath allows for a consistently smooth finish on an ABS print by exposing it to the fumes of acetone, which readily vaporize at room temperature. Compare to other finishing methods, doing an acetone vapor bath requires so much less effort but produces exceptional results.
4. Less hygroscopic
All 3D printing filaments are hygroscopic, which means that they readily take up moisture from the air. Between filaments, however, some are simply more hygroscopic than others. Comparing ABS with PETG, ABS is a bit less prone to moisture intake, making it easier to handle and store.
Drawbacks
1. Hard to work with
The high-temperature nature of ABS makes it one of the most notoriously difficult filaments to work with. Not only do you have to contend with the usual challenges of printing at high temperatures (like stringing and “heat creep” in the extruder), but there’s also the fact that ABS has poor layer adhesion and shrinks by a large margin when it cools.
In terms of getting your first layer to stick to the build platform, ABS might just be the most finicky filament. It has a high tendency to warp, making it necessary to use a heated bed with a good adhesion aid such as ABS glue or Kapton tape. You might even need to resort to other measures, like printing a raft or brim on your project’s first layer or using a print chamber to further slow down the cooling process.
For these reasons, ABS isn’t exactly a filament we would consider beginner-friendly. The results are worth the effort in the end, but there’s still just so much effort involved.
2. Prints at very high temperature
The high-temperature characteristic of ABS might be desirable for the end-product, but it also means that you’ll be using a lot of power during the printing process. Granted that PETG prints only at slightly lower temperatures, but the difference can add up over many hours and really hurt your power bill.
3. Produces noxious fumes
Another distinct disadvantage of working with ABS is that it produces a lot of styrene gas while printing. Not only is this gas irritating and noxious, but it is also a known carcinogenic. This means that you should never print with ABS in a room without ventilation. Even then, you would not want to stay in the same room as a 3D printer that is extruding ABS.
What is PETG?
Polyethylene terephthalate (PET) is undoubtedly familiar to anyone, as it’s the most widely used plastic in the world, especially for consumer goods. PETG is merely a variation which has been glycol-enhanced. The addition of a glycol group to the standard PET chemical structure makes it a little more flexible, less rigid, more chemically stable, and more heat stable. PETG also has improved optical properties and is a little clearer and more suitable for labelling than PET.
With its excellent stability in a variety of harsh conditions, PETG has often been the material of choice for outdoor signages, food containers, prosthetic devices, and medical equipment that need to be autoclaved regularly.
Advantages of PETG
1. Better impact resistance
PETG has higher flexibility and ductility compared to both standard PET, ABS, and even PLA. This means that PETG is able to deform very slightly upon impact, giving it greater resistance to the sudden or sustained application of force. This is one of its more unique characteristics and is a property that PETG is known for.
2. Not as prone to warping
PETG and ABS may both be high-temperature filaments, but their ease of use properties are miles apart. The benefits of PETG are two-fold: not only is its shrinkage upon cooling much less pronounced, but it also has excellent layer adhesion. With this combination, warping becomes less of an issue when working with PETG, although you might still need a heated print bed. A PETG print typically doesn’t require an enclosed print chamber.
PETG may be less durable than ABS, but its layer-to-layer adhesion somehow makes up for it. The strength of PETG prints is more isotropic, so it can better handle loads that run perpendicular to the direction of the layers. In fact, PETG sticks so well to the print bed that it’s recommended to use an adhesion aid that peels off easily, such as tape or hairspray.
3. Doesn’t produce unpleasant odors while printing
A major reason why many 3D printing professionals have started to shift from PETG to ABS is the fact that PETG prints without releasing any unpleasant odor or toxic gases. This is a significant safety and health upgrade.
Although PETG causes no perceivable odor, we still recommend having good ventilation in your working area. 3D printing naturally releases plastic microparticles in the air that could get into your lungs. In addition to having good air circulation, it’s best to have respiratory protection whenever you work closely with a running 3D printer.
4. More chemically resistant
Standard PET is already quite the chemically-stable plastic, but the addition of glycol’s ring structure makes PETG impervious to a range of acids, bases, and solvents. Prosthetic devices that are in constant contact with biological agents benefit from this level of stability. However, this is a double-edged sword in the case of 3D printing – while the end-products of PETG are undoubtedly durable and long-lasting, this same property makes PETG stubbornly hard to post-process.
5. Can be used to for clear 3D prints
PETG is considered by many to the best filament for printing clear objects that let as much light as possible pass through, even with minimal post-processing. This is because PETG is a naturally clear plastic – it is only through additives that it gains color.
The case for ABS is the exact opposite. ABS is not a clear plastic and has to be treated to become somewhat clear. Even with chemical additives and post-processing via vapor acetone bath, the best that you can get with ABS is a translucent finish. Even PLA or Polycarbonate would be better options than ABS if you want to 3D print something clear.
Drawbacks of PETG
1. Reduced rigidity
Compared to ABS, PETG is less rigid and less brittle. While this gives PETG the advantage of a higher impact-resistance, it also makes PETG less suitable for applications that require good rigidity. Since PETG deforms under pressure, it gives inadequate protection as a container for fragile objects.
2. Tough to finish
ABS can be finished to perfection in a few minutes using an acetone vapor bath. PETG, on the other hand, has no such advantage. While there are solvents that can dissolve PETG, these solvents are of the hazardous kind and are almost impossible to acquire.
If you want to get a smooth finish on your PETG print, your best choice would be to do sanding and polishing. Even then, the ductile nature of PETG makes it difficult to finish using mechanical methods. Heat treatment may be an option, but we would advise it if you’ve never used a heat gun before.
3. Expensive
A standard 1-kilogram spool of PETG filament will set you back around $25. A spool of ABS of similar weight would be at least 20% cheaper, with a lot of even lower-priced options. The price difference isn’t much if you’re only going through one or two spools per year. As PETG use becomes more common, we expect more brands to sell it and further reduce the price gap.
Which filament should you use?
It may sound like PETG has a lot of advantages over ABS, and we agree. Nowadays, there’s very little reason for why one would choose ABS over PETG. However, human nature naturally resists change, and ABS has managed to gain a firm foothold on the 3D printing community. Both filaments still have merit, as we summarize below:
Print with ABS if…
1. You need something more rigid and heat-resistant
Despite the strength and heat stability of PETG, ABS still holds a slight edge in these two categories. ABS is suitable as a container for handling boiling fluids and its rigidity means that it acts as a better protective barrier for its contents.
2. You want to get a smooth finish the easy way
Let’s face it: finishing an ABS print using an acetone vapor bath is, by far, the easiest way to make a smooth 3D printing project. It’s quick, doesn’t take a lot of skill, and it takes very little effort. If you’ve ever seen an ABS print done with perfection, then you’ll understand why a lot of 3D printing hobbyists and professionals still use ABS.
3. You’re on a budget
It’s a bit of a stretch, but you can save a few dollars by sticking to ABS instead of PETG. The difference isn’t really that small, and we’re already seeing PETG and ABS filaments that are just about priced the same.
Print with PETG if…
1. You need something that can withstand more impact
The brittleness of ABS means that it can easily shatter or crack when subjected to a strong impact. This is not the case with PETG. When PETG experiences an impact, it can deform but essentially remains intact. This gives PETG extra longevity that is suitable for reusable food and drink containers and tools used in the medical field. Under the right circumstances, PETG can be made to be so strong that industry pundits have taken to describing it as “virtually unbreakable.”
2. You’re printing a project for outdoor use
The heat stability of PETG may be a notch lower than ABS, but PETG makes up for it with far superior chemical stability. For this reason, PETG has become the go-to material for companies who want to put up outdoor signages. Not only can PETG withstand the extreme temperature of a sunny day, but it also doesn’t degrade with sustained exposure to UV radiation.
3. You don’t want to deal with printing issues
PETG has often been described as a filament that combines the strength of ABS and the ease of use of PLA. This description is the perfect summary for why a lot of 3D printing professionals and hobbyists have started to print mostly with PETG. It’s a lot more forgiving than ABS when it comes to warping and layer adhesion and does not release irritating and harmful odors.
Final thoughts
ABS may be one of the vanguards in the mainstream popularity of 3D printing, but it’s pretty apparent that there are now better alternatives to it. More environment-conscious 3D printing hobbyists and professionals are shifting to PLA because of its biodegradable nature, but those who long for the strength of ABS have a worthy alternative – PETG.
PETG hasn’t quite hit the level of appeal of ABS yet, but we think it’s only a matter of time before more people realize its potential. It’s better in many ways, easier to use, and can be used to create near-transparent 3D prints. While not the perfect filament by any means, PETG has enough merit to be considered THE up and coming filament material in the world of 3D printing.
