PET & PETG sound very similar, but I wondered how different they actually are. This article is going to give you a quick comparison between these two filaments.
Before we dive into the world of filaments and the differences between these two, it is important to have an idea what PET and PETG are and what they do exactly.
Polyethylene terephthalate or PET for short and polyethylene terephthalate glycol or PETG are thermostatic polyesters.
They are great for usage in the manufacturing industries because they are easy to form, durable, and they are significantly resistant to chemicals.
Another reason is that they form easily at low temperatures and this is what makes them popular among 3D printing industries. If these 2 filaments are so alike in what they are used for, then you may be wondering what actual differences they have.
Keep on reading for an informative comparison between PET & PETG, so you can finally know the actual differences.
What’s the Difference Between PET & PETG?
PET is a filament containing two different monomers named above. PETG also contains the same monomers, but it has an extra monomer which is glycol.
The addition of glycol changes its form and creates a totally new kind of plastic, adding more flexibility to it, and reduces how much moisture it absorbs.
You may wonder why the addition of glycol is necessary since PET is already a great filament. Well, PET as great a filament it is, has its own shortcomings. One of it is the hazing effect it produces during heating.
LulzBot Taulman T-Glase PET is a pretty solid spool of filament that many people enjoy. It has a high gloss finish and comes in many colors, for your enjoyment. Do keep in mind, its recommended for intermediate users rather than beginners.
The glycol added in PETG helps to remove this hazing effect. There is also the fact that normal PET filaments can become bristle due to crystallization effects.
Adding the glycol will help to soften the exterior of the resulting printout and provides an easy grip.
To put things in perspective, if you are looking to get a printout that is not soft to the touch but rather rough on the edges and rigid, then you use PET filaments. However, if the finishing you are looking to get is a flexible, then you use PETG.
If you want a filament that works a little better for beginners, get yourself some OVERTURE PETG Filament with 3D Build Surface from Amazon. It’s probably one of the most popular filament brands for PETG out there, because it does the job so well.
Another major difference between PET and PETG has to do with the finishing of the resulting product. While prints made out of PET are considerably harder than those made with PETG, they are also more likely to get broken easily.
As PET is subjected to higher stress, it can easily be broken when used for 3D prints unlike PETG. This simply means that PETG has greater impact resistance than PET.
Furthermore, PET is a lot more hygroscopic compared to PETG, meaning it absorbs more moisture in the air. You wouldn’t want to leave any type of filament in a humid environment, but some filaments are a lot worse off.
This property makes PETG more resilient than PET.
If a wet PET is heated, the PET can become hydrolyzed by the water present. The only solution to this problem is to make sure PET is not heated when wet. This can be achieved by drying or making use of a desiccant.
I’d recommend using the SUNLU Dry Box for Filament for pretty much all 3D printer users out there who want the top quality.
You can finally eliminate the worry and frustration that comes about with printing with moisture-ridden filament. Many people don’t even realize they are being negatively affected by it.
This dry box has a default drying time of 6 hours at a designated temperature setting and works with all mainstream brands of filament. For most filament, you only need between 3-6 hours of drying.
The ultra-quiet design means that you are operating at a very low 10dB which will barely be noticeable.
Temperature Differences of PET vs. PETG
PET is said to print at a slightly higher temperature than PETG, but for the most part, the printing temperatures are very similar. Taulman T-Glase PET prints at 240°C while many users of OVERTURE PETG filament actually got successful prints at 250°C.
What is PETG Filament Good For?
PETG is useful in a variety of industries. It can be used for packaging by manufacturing industries. Finished products of PETG includes bottles, covers, glazing, POP (point of purchase) graphic displays and so on.
It also has important applications in the medical line as it is commonly used to construct medical braces. PETG gained a lot of recognition in 2020 due to the fact that it was easily molded into face shields used to protect the wearer from others.
It was also easily cleaned and disinfected, which made its usage quite popular. When used in tests requiring chemicals or even radiation, PETG has been shown to hold its own. It does not react to chemicals unlike PET, PETG is not hygroscopic.
This means that it doesn’t absorb water from its surroundings.
Based on its composition, PETG is not toxic and can be used to package food, and it is also not harmful to the skin. In 3d printing, PETG is perfect for printing because it has a low shrinkage rate.
This means that when it is processed, it doesn’t warp. This feature makes PETG ideal for making large 3D prints. Although softer than PET, PETG is very flexible and ideal in situations where the prints are needed to be crack or break resistant.
The print comes out odorless too!
It is now evident that PETG is obviously more advantageous than PET when it comes to 3D printing, and it is most often recommended in most use-cases. However, despite the numerous advantages of PETG, there are a few shortcomings to it.
As it is softer, it is more prone to damage by scratches, UV light, and it doesn’t do well under autoclave conditions.
PETG is a good alternative to ABS, since it has a similar strength but much lower warping.
Is PETG Harder Than PET?
PETG is actually more flexible than PET. Although PETG AND pet look similar to each other, one fundamental difference is how hard they are. PET combines two monomers which in its raw state is crystalline, and harder in nature.
The addition of glycol in PETG makes it softer and less brittle than PET. This new added material also makes PETG more shock resistant.
To conclude, when it comes to 3D printing, both PET and PETG give amazing results. Usage of these two filaments depends on the kind of finish and durability the printer is looking to achieve.