How Heat Resistant Is PETG? (Detailed Analysis)

With so many factors that cause filament types to have a different set of strengths and weaknesses, it’s never an easy process to choose the best filament for your project.

Strength, stiffness, durability, water resistance, heat resistance are just a few of the properties that you need to consider, with many more that we won’t mention right now to avoid dragging the list on and on.

Due to PETG being one of the most popular filament types right now, we decided to write today’s article on the heat resistance property of PETG in particular, as we believe that heat resistance is one of the first things that come to mind.

So, how heat resistant is PETG?

While the exact figure varies between different spools of PETG filament due to differences in the manufacturing process and the material composition, PETG, on average, can withstand temperatures up to 80-85 degrees Celsius before starting to deform and lose its rigidity.

Moving forward, we will take a deeper look at the heat resistance property of PETG and discuss whether PETG is a good choice for projects where the model would be in a hot environment for prolonged amounts of time.

How Heat Resistant Is PETG?

PETG is one of the better filaments for heat resistance, making it a suitable pick for many applications where you intend to expose the plastic to heat.

On average, PETG can tolerate heat up to the levels of 80 to 85 degrees Celsius, which is the point known as its glass transition temperature.

Even though it doesn’t fully liquefy, PETG starts losing its shape and rigidity when it hits its glass transition temperature, making the glass transition temperature the primary factor for determining its heat resistance.

It’s vital to keep in mind that the glass transition temperature is the factor that determines the heat resistance and not the melting point, which is the point where PETG liquefies.

While PETG has a melting point of 230-250 degrees Celsius on average, it will entirely soften and lose its shape long before (at the glass transition temperature of 80-85 degrees Celsius) it hits these temperatures.

Remember that the averages give us a simple way to decide whether PETG could be suitable for a project or not, but finding out the exact glass transition temperature of the filament you have before using it on a project to ensure safety is vital.

To find the exact heat resistance capability of your PETG filament, we recommend checking the packaging or visiting the manufacturer’s website for the actual glass transition temperature value.

As most reputable brands denote this information, you most likely won’t have any trouble finding this information relatively quickly.

We recommend leaving a margin of at least 5 degrees between the glass transition temperature of the filament and the temperature of the environment to stay on the safe side and compensate for any possible errors.

What Is the Softening Temperature of PETG?

PETG’s softening temperature is a vital factor to keep in mind before carrying on with a project, as it determines the point where PETG won’t be able to hold its shape anymore.

The softening temperature of PETG is the same thing as its glass transition temperature in essence (that also determines its heat resistance), which is between 80 and 85 degrees Celsius on average.

At these temperatures, PETG will increasingly become softer and lose its shape, essentially meaning that it cannot withstand the heat anymore while staying rigid.

Keep in mind that the exact softening temperature will vary between different brands of PETG due to the differences in the manufacturing process.

Is PETG Good for Heat?

Now that we know how heat resistant PETG is – let’s find out whether PETG is a good option for projects where heat resistance is vital.

While behind filament types such as ABS, HIPS, ASA, and Polycarbonate, the heat resistance capability of PETG is sufficient for most applications.

With filament types such as Polycarbonate, ABS, and HIPS requiring more advanced tools such as an all-metal hotend or an enclosure, we can say that PETG offers a balance between accessibility and heat resistance, usually making it a good choice.

Is PETG More Heat Resistant than ABS?

ABS is one of the first filament types that come to mind for heat resistance, so let’s find out how it compares to PETG.

ABS has a glass transition temperature of 105 degrees Celsius on average, whereas this value is only 85 degrees Celsius for PETG. By looking at these figures, we can comfortably say that ABS is more heat-resistant than a PETG.

That being said, as ABS is harder to print and requires a heated bed, you can feel free to go with PETG if the heat resistance is sufficient for the purposes of your project.

Is PETG More Heat Resistant than PLA?

As it’s undeniable that PLA is the most popular filament on the market right now, let’s take a quick look at how it compares to PETG in terms of heat resistance.

While PLA has a glass transition temperature of 60 degrees Celsius on average, this value is 85 degrees for PETG, making PETG the more heat-resistant choice.

As the heat resistance of PLA is way too low for most applications, PETG is usually the more suitable choice between the two.

Wrapping Up

While not the most heat resistant filament type on the market, PETG does well enough in the heat resistance department, especially against PLA, its number one rival in terms of popularity.

To quickly summarize, a model printed with an average spool of PETG filament should be able to resist heat levels up to 80-85 degrees Celsius, which is the glass transition temperature of PETG.

That being said – as each manufacturer uses a different process and composition of materials for the PETG filament they produce, the exact figure usually varies between brands of PETG.

We highly recommend finding the exact glass transition temperature of the PETG filament you have before going through with a project and refrain from using the average values to make a final decision.

Happy printing!