Is PETG Good for Outdoor Use? PETG Vs ASA

PETG, or polyethylene terephthalate glycol, is a material that is slowly gaining popularity in the 3D printing arena. One of the most common questions that many 3D printing enthusiasts ask is whether PETG is suitable for outdoor use.

PETG is a good material for outdoor use because of its exceptional strength and resistance to environmental elements such as sunlight and water. Most 3D printing enthusiasts prefer it over other 3D printing materials because it is easier to print compared to ABS.

In this article, I will go into detail about some of the properties of PETG that make it good for outdoor use, so keep reading the rest of the article to learn more.

Is PETG Good for Outdoor Use?

PETG is a good material for outdoor use as it has excellent mechanical and physical properties that make it more resistant to harsh weather conditions than other 3D printing materials. Here are some of the characteristics of PETG that make it good for outdoor use:

• UV resistance
• Heat resistance
• High strength and flexibility
• Weather resistance

UV Resistance

PETG has good UV resistance, so it can withstand exposure to UV radiation without physically deforming or discoloring. This property makes it the perfect material for outdoor prints. PETG is particularly less susceptible to UV compared to PLA and ABS.

However, it is not 100% immune, so leaving it exposed for a long time might cause it to change color slightly. You can use UV-resistant varnish like the Krylon Gallery Series Artist and Clear Coating Aerosol found on Amazon to increase protection against UV radiation.

This user printed a UV-resistant birdhouse using PETG and left it in the sunlight for a few years, but it didn’t fade or deteriorate at all.

One user said that he printed some PETG parts for outdoor use back in 2017, adding that those parts were under constant compression and they held up some planters. However, they were still in good condition at the time of writing as they resisted UV degradation well.

Another user who printed PETG pond fittings mentioned that PETG was fairly UV stable, better than ABS but slightly lesser than ASA or PLA. He added that he had left them outside for 3 to 4 years but saw no sign of degradation. Additionally, he recommended acrylic spray to help reduce discoloration.

Heat Resistance

If you’re looking for a material that can withstand heat without warping, then PETG might be the solution. It holds up well against heat due to its fairly high glass transition temperature (85°C) and heat deflection temperature (70°C).

One user mentioned that PETG was much better at printing functional parts because it had good temperature stability, flexibility, and durability. He added that he had printed an HTD belt pulley for an electric skateboard that lasted 100s of miles without melting or wearing out.

Here is a video that shows how a tiki torch holder printed with PETG behaves when exposed to sunlight for a day in comparison to that printed with PLA.

Another user printed an exterior plaque with raised letters out of PETG and left it in direct sunlight every day for several hours, and after three months, it still looked as good as the day he printed it.

However, PETG might still warp when the temperature approaches or surpasses its glass transition temperature since it starts to lose its mechanical strength earlier—for example, temperatures inside a car on an extremely hot day.

A user who printed a black PETG phone mount using PETG showed how the Texas heat warped it when he left it in his car.

Someone commented they needed to print with white PETG since the black one absorbs more heat. Another person who had printed a phone mount for his car with clear PETG also added that his mount had not incurred any damage.

Check out this video that shows how PETG holds up when left in a car on hot days compared to other filaments.

High Strength and Flexibility

One of the reasons PETG is a popular choice for outdoor applications is its high strength and flexibility. It has a high impact strength that allows it to withstand sudden impact without breaking.

In addition, its high tensile strength increases its flexibility, meaning it will not suddenly shatter or fracture when you overload it. Instead, it will just bend. This is why many 3D printing enthusiasts use it to make items like bike fenders and Frisbees.

One user said that he used PETG when he wanted a part that could flex without snapping. He printed some hooks to keep his shed doors open with PLA, but they snapped, especially when exposed to the harsh Florida heat. However, they held up very well when he used PETG.

Here is an interesting video by CNC Kitchen that compares the performance of PLA, PETG, and ASA when loaded at a constant speed.

Weather Resistance

PETG exhibits great weather resistance thanks to all the properties I have mentioned above. First, it can resist strong winds due to its strength and flexibility. Secondly, it fares well against UV radiation and heat. PETG is also water-resistant, so water will not affect its strength.

This means that exposure to extreme weather conditions such as scorching sunlight, heavy rains, or strong winds will not affect your PETG prints in any way.

One user 3D printed 40mm hinges using PETG to hold up his 20-pound solar panel and left it outdoors to see how it stood against various elements such as sunlight, snow, and rain.

According to his latest update a couple of months later, the PETG hinges were still holding perfectly strong despite the extreme shifts in weather.

Another user printed a hub cap for their garden trailer using ordinary PETG. The cap was exposed to UK weather for years, including rainfall and sunshine, but it performed well. They stated that the secret to making tough prints was using enough perimeters and top and bottom layers.

Check out this video that illustrates PETG’s weather resistance when exposed to outdoor elements for two years.

PETG Vs ASA for Outdoor Use

PETG and ASA are two of the best options when it comes to printing objects to use in an outdoor environment. However, most users consider ASA a much better material when you look at several aspects.

When it comes to heat resistance, ASA outdoes PETG. ASA has a glass transition temperature of 112°C and heat deflection temperature of 92°C, while PETG has 85 and 70°C, respectively. This shows that ASA can withstand heat better than PETG.

One user 3D printed an owl using ASA to keep crows and pigeons from his wife’s garden. He stated that the print resisted direct sunlight and had not warped in years. He then recommended opaque PETG as the next best filament to use outdoors.

In terms of UV resistance, PETG slightly discolors after prolonged exposure, although it doesn’t deform. However, ASA has a higher resistance to UV radiation, so it won’t change color or break down when exposed to sunlight for long periods.

Another user printed Christmas light clips out of ASA, and they remained outside of his house for over a year. He mentioned that ASA had better UV protection and weather resistance than other materials. However, he said that ASA warped a lot. In that case, you could opt for PETG.

ASA also has a higher impact resistance than PETG. This means ASA can absorb more energy during impact without deforming or cracking. For example, a face shield printed with ASA will be less likely to break than PETG when flying debris hits it.

Here is a video that compares the suitability of using PLA, ABS, PETG, ASA, TPU, and Nylon to print tools, gear, and gadgets for outdoor use.

ASA is more expensive than PETG, with a Polymaker ASA 1KG Filament Spool costing around $30 on Amazon. On the other hand, a Polymaker PETG 1KG Filament Spool costs roughly $25 on Amazon.

Below are some of the pros and cons of using PETG and ASA for outdoor use:

PETG for Outdoor Use Pros

• Has a good impact resistance ability
• Easier to print compared to other materials like ABS
• Can be recycled, which makes it an environmentally friendly option
• Is food-safe, which makes it suitable for applications in the food industry and beverages
• Exhibits good UV resistance, which means that it can be used outdoors without degrading

PETG for Outdoor Use Cons

• Difficult to sand, making it hard to achieve a smooth surface finish
• Moisture can affect the printing process and cause poor print quality
• Has a lower temperature resistance when compared to other materials like ASA and polycarbonate

ASA for Outdoor Use Pros

• ASA is excellent at resisting UV radiation and exposure to harsh environmental conditions without degrading
• Relatively easy to print and can be printed at a lower temperature compared to other materials, such as ABS.
• Has good impact resistance, making it suitable for making objects you could use outdoors, such as car grilles.
• ASA is easy to post-process to achieve a smoother finish or customize the print
• Does not discolor over time, even after exposure to sunlight

ASA for Outdoor Use Cons

• ASA produces toxic fumes during printing which can be a major concern for other users
• Warping and shrinking of ASA can make printing relatively difficult