3D Printing Guide

ASA vs PETG: Pros, Cons, and Best Uses

Paul Chow

Updated on December 30, 2024

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Choosing the right filament is one of the most critical decisions in 3D printing. Every filament has unique strengths and quirks, and understanding those differences can mean the difference between a flawless print and a stringy mess. Among the many options out there, ASA (Acrylonitrile Styrene Acrylate) and PETG (Polyethylene Terephthalate Glycol) stand out as two heavy hitters, each offering a blend of durability, functionality, and versatility.

From weatherproof enclosures to chemical-resistant tools, ASA and PETG each shine in specific scenarios. Here’s a detailed breakdown of these two filament options.

What is ASA?

ASA, or Acrylonitrile Styrene Acrylate, is a thermoplastic filament engineered for durability and performance, particularly in outdoor environments. It is often described as more durable and resistant to weather than ABS.

Originally developed as a substitute for ABS, it maintains similar strength and rigidity while providing significantly better resistance to UV rays, heat, and adverse weather conditions. This makes ASA an excellent choice for applications where exposure to sunlight, temperature fluctuations, and moisture would cause other filaments to degrade over time.

Below are some of its key features:

UV and Weather Resistance: ASA is built for the outdoors. Whether it’s for garden tools, outdoor signs, or automotive trim, this filament won’t break down or discolor when exposed to sunlight, rain, or snow.
High Impact Strength: Durability is another strong suit of ASA. It can handle stress and impacts without cracking, making it reliable for functional parts that endure regular use or occasional bumps and drops.
Smooth Matte Finish: Unlike the glossy appearance of many filaments, ASA produces a professional matte finish. This not only enhances its aesthetic appeal but also hides minor surface imperfections better than shinier alternatives.

However, ASA isn’t without its quirks. It requires higher temperatures and careful control of the printing environment. Nozzle temps range from 250–260°C, and the bed needs to stay at 90–110°C. To avoid warping or cracking, an enclosed chamber is also recommended

Plus, ASA gives off noticeable fumes, so you must have proper ventilation.

Applications for ASA

With its resistance to weather, impact strength, and sleek finish, ASA is a top pick for outdoor and industrial projects. Engineers, designers, and DIYers alike use it for:

Automotive Parts: Durable and weatherproof, perfect for car trim or exterior components.
Outdoor Fixtures: From garden tools to signs, ASA can endure sun, rain, and snow without losing its shape or color.
Industrial Prototypes: When you need a part that can handle tough conditions and still look professional, ASA is up to the task.

ASA’s defining characteristic is its ability to withstand the elements. Where other filaments may yellow, crack, or warp after prolonged exposure to the outdoors, ASA holds its own, making it the material of choice for outdoor fixtures, automotive parts, and industrial components. Its resistance to UV radiation means that it won’t lose mechanical integrity or aesthetic appeal, even under harsh sunlight.

If your project needs strength, weather resistance, and a professional finish, ASA is a filament worth adding to your toolkit.

What is PETG?

PETG, or Polyethylene Terephthalate Glycol, is a modified version of PET (the same material commonly found in water bottles and food containers). The addition of glycol during its production enhances its properties, making it less brittle and easier to process in 3D printing.

Known for its strength, chemical resistance, and ease of use, PETG is often seen as a bridge between beginner-friendly PLA filament and the more demanding ABS or ASA. Its unique combination of properties makes it a favorite among makers who need durability without sacrificing printability or aesthetics.

Here are some of its key features:

Chemical Resistance: PETG excels in environments where exposure to chemicals like oils, acids, or cleaning agents is expected. This makes it an excellent choice for custom containers, machine parts, and medical applications.
Durability and Flexibility: While not as rigid as ABS or ASA, PETG offers a good balance of strength and flexibility. It can absorb impacts and handle mechanical stress without breaking, making it suitable for load-bearing or functional components.
Ease of Printing: PETG is widely recognized for its printability. It doesn’t warp as much as ABS, and its minimal shrinkage allows for clean, reliable prints on open-frame printers. It typically prints at temperatures of 220–250°C for the nozzle and 70–90°C for the bed. A heated bed helps adhesion, but an enclosure isn’t necessary.
Glossy Finish: PETG delivers a natural glossy finish that enhances the aesthetics of printed parts. This transparency and sheen make it a favorite for producing visually appealing prototypes or display pieces.

Unlike ABS or ASA, PETG is easy to print, with minimal warping and no requirement for an enclosed print chamber.

Applications for PETG

PETG is a versatile filament well-suited for a wide range of projects, such as functional and decorative prints. It’s commonly used for functional parts like mechanical components, protective housings, and custom containers. Plus, it has chemical resistance that makes it ideal for parts exposed to oils, acids, and solvents, and some toughness and flexibility that allow it to handle mechanical stress without cracking or breaking.

Its glossy finish makes it suitable for aesthetic applications like display models and artistic prints as well.

Common Differences Between ASA and PETG

Understanding the differences between ASA and PETG is essential for advanced users who want to make informed decisions about their materials. These filaments excel in distinct areas, making each suitable for specific applications.

Below is a quick comparison table. We’ll have more detailed discussions of the key differences below.

Property	ASA	PETG
UV Resistance	Excellent, ideal for outdoor use	Moderate, suitable for indoor applications
Impact Strength	High, durable under stress	Good, flexible for moderate loads
Printing Difficulty	High, requires enclosure and high temperature (250–260°C)	Moderate, prints best at lower temperatures (220–260°C)
Bed Temperature	Requires heated bed (90-110°C)	Does not require a heated bed, easier to print
Flexibility	Moderate, rigid but not brittle	High, offers elasticity without breaking
Chemical Resistance	Moderate, resistant to some chemicals	Excellent, handles acids, oils, solvents
Finish	Matte, good at hiding imperfections	Glossy, great for aesthetics
Cost	Slightly higher, due to specialized properties	Moderate, cost-effective, and accessible

UV Resistance

ASA is engineered for outdoor durability. Its exceptional UV resistance ensures that prolonged exposure to sunlight doesn’t degrade its mechanical properties or appearance. This makes ASA an excellent choice for applications like automotive trims, outdoor fixtures, and signage. It retains its color and strength even after years in harsh environments, outperforming PETG and other commonly used filaments.

PETG, on the other hand, provides moderate UV resistance, making it suitable for indoor or short-term outdoor use. However, prolonged sunlight exposure can lead to discoloration and a gradual weakening of the material. If your project involves primarily indoor use or occasional outdoor exposure, PETG is a reliable choice.

Impact Strength

ASA’s impact strength is one of its standout features, making it ideal for functional parts that endure mechanical stress. Its toughness makes it suitable for industrial applications, where reliability is crucial. For example, ASA is commonly used in prototypes for engineering-grade parts that require rigorous testing.

PETG offers good impact resistance with a touch of flexibility, which helps it absorb shocks without cracking. This makes it a popular choice for items like protective cases, brackets, and household tools. However, under heavy or repetitive stress, PETG may not hold up as well as ASA.

Printing Difficulty

Printing ASA is not for the faint of heart. It requires a high nozzle (250–260°C) and bed temperatures (90–110°C), as well as an enclosed print chamber to prevent warping and layer splitting. Additionally, ASA emits noticeable fumes during printing, necessitating good ventilation. These challenges mean ASA is better suited for experienced users with advanced setups.

PETG, on the other hand, is more forgiving. It prints at lower temperatures (220–260°C for the nozzle, 70–90°C for the bed) and doesn’t require an enclosure. Its excellent layer adhesion and low warping tendencies make it an easier filament to work with, even for users without high-end equipment. However, PETG’s tendency to string and blob requires precise tuning of retraction settings.

Bed Temperature

ASA exhibits excellent heat resistance, allowing it to maintain structural integrity in high-temperature environments. This makes it particularly suitable for parts exposed to heat, such as automotive components and machine housings. ASA typically requires a heated bed temperature of 90–110°C during printing to minimize warping and ensure optimal adhesion.

While PETG performs well in moderate heat, it begins to soften at lower temperatures compared to ASA. In fact, it generally requires a bed temperature of around 70–80°C, which is lower than that of ASA, making it easier to print but less suitable for applications that demand high thermal resistance

Flexibility

ASA offers moderate flexibility but leans more toward rigidity, making it ideal for parts that demand dimensional stability over elasticity. This ensures that printed components maintain their shape under stress, which is critical for structural applications.

While it can handle some degree of bending, ASA is better suited for parts where stiffness and strength are prioritized, such as brackets, enclosures, and mechanical fixtures. Its rigidity also means it’s less prone to deformation under load, a key consideration for functional and industrial use cases.

PETG shines in its ability to combine flexibility with durability, allowing it to bend under stress without cracking or breaking. This makes it particularly well-suited for applications requiring a degree of give, such as snap-fit enclosures, protective cases, and living hinges. Its flexibility also enhances impact resistance, enabling PETG parts to absorb shocks without permanent damage. For applications where elasticity is essential without compromising strength, PETG is a reliable choice.

Chemical Resistance

While ASA offers moderate chemical resistance, it doesn’t perform as well as PETG in chemically aggressive environments. It can handle exposure to certain oils and mild chemicals, making it suitable for general-purpose applications where chemical exposure is limited. However, prolonged contact with strong acids or solvents may cause degradation. ASA works well in scenarios where the primary focus is mechanical performance with incidental chemical resistance.

Unlike ASA, PETG’s chemical resistance is one of its standout features, excelling in environments where exposure to harsh substances is unavoidable. It can resist oils, acids, and solvents without losing its structural integrity, making it ideal for lab equipment, storage containers, and industrial components. This capability also extends to food-safe applications, where chemical stability is critical.

PETG’s superior resistance to corrosion and breakdown ensures it remains a top choice for chemically demanding projects.

Finish

ASA produces a smooth, matte finish that provides a professional appearance and effectively hides minor imperfections. This characteristic makes it an excellent choice for parts where aesthetics matter but without the need for a glossy shine. The matte surface also reduces glare, which can be beneficial for functional components exposed to sunlight or artificial lighting.

If your project demands a clean, understated look, ASA’s finish is well-suited to deliver.

Meanwhile, PETG is known for its glossy finish, which adds a polished, high-quality look to printed parts. This makes it a preferred choice for display models, consumer-facing prototypes, and decorative items. The shiny surface enhances the visual appeal of prints, making PETG ideal for projects where aesthetics are as important as functionality. While the glossy finish may reveal imperfections more readily than ASA’s matte surface, careful print settings can help achieve a flawless result.

Cost

When it comes to cost, ASA tends to be more expensive than PETG due to its specialized properties, such as UV resistance and high-temperature durability. While this higher upfront cost might be a drawback for some, ASA’s resilience and long-term reliability can offset the expense by reducing the need for replacements.

For projects that require exceptional outdoor durability or mechanical performance, ASA’s cost is justified by its superior capabilities. In professional or industrial settings, the investment often pays off through extended part lifespans.

Differing from ASA, PETG is generally more affordable, making it a cost-effective option for a wide range of applications. Its combination of durability, flexibility, and chemical resistance offers excellent value, particularly for users on a budget. PETG’s widespread availability also makes it accessible for hobbyists and professionals alike. For projects that don’t require extreme durability or outdoor resilience, PETG provides a reliable and economical alternative to pricier filaments.

When to Use ASA or PETG

Selecting the right filament for your project is all about understanding the unique strengths of ASA and PETG. Both filaments are highly versatile, but they excel in different scenarios.

Where ASA Truly Shines

If your project will be exposed to prolonged sunlight or outdoor elements, ASA is the ideal choice. Its excellent UV resistance and weatherproof properties help maintain structural integrity and prevent yellowing or cracking, making it perfect for items like garden tools, automotive trims, and outdoor signage.

In demanding environments where high temperatures and durability are important, such as components near engines, protective covers for industrial machinery, or custom trim parts for cars, motorcycles, or boats, ASA is your go-to as it maintains its shape and strength under thermal stress, outperforming PETG in both impact resistance and thermal stability.

Additionally, when it comes to finishes, ASA’s professional matte finish gives a sleek, low-glare appearance that’s well-suited for industrial applications such as testing devices for fieldwork, custom casings for electronics, or industrial tool handles. It conceals minor surface imperfections, giving an ideal polished look from prototypes to finished products.

When To Choose PETG

For chemical-resistant parts for food-safe or industrial applications, PETG should be your go-to filament. Its superior chemical resistance makes it ideal for components exposed to oils, acids, and solvents, while food-safe certifications allow for applications such as food storage containers and kitchen utensils.

If your project demands flexibility without compromising strength, PETG offers the perfect balance. It can bend under stress without breaking, making it ideal for snap-fit parts, protective phone cases, and components that require a bit of give. Its flexibility also enhances impact resistance, making it a smart choice for parts that need to absorb shocks.

On top of that, PETG is one of the easiest filaments to print with. Unlike ASA, which doesn’t require an enclosure, it is less prone to warping and emits minimal fumes. This ease of use makes PETG accessible to both hobbyists and professionals who want strong, durable prints with minimal setup and troubleshooting.

What NOT to Use ASA or PETG For

Both ASA and PETG are versatile and reliable filaments, but they aren’t suitable for every application. Each has specific limitations that could affect the performance or safety of your prints if used incorrectly.

Where ASA Falls Short

While ASA’s matte finish is excellent for professional applications, it is not the best option for indoor aesthetic projects where a glossy, polished finish is a priority, for instance, decorations, figurines, or any display items. For visually appealing projects, PETG would be a better choice.

Additionally, ASA should never be used for food-safe applications. It’s not certified as food-safe, and there’s a risk of chemical leaching, making it unsuitable for kitchenware, food storage containers, or any items intended to come into contact with consumables, such as food or beverages.

Moreover, ASA releases noticeable fumes during printing, which can be irritating in small, closed spaces like home offices. If you’re printing in a shared living space or a room with poor ventilation, consider using PETG or PLA, which emit far fewer fumes.

When PETG Isn’t The Right Fit

PETG isn’t the best choice for extreme outdoor conditions. While it can handle brief exposure to sunlight and weather, prolonged exposure to UV rays can cause discoloration and weaken the material over time. If you need a filament for outdoor fixtures or parts exposed to constant weathering, such as outdoor signs, patio furniture parts, or garden fixtures, ASA is a more reliable option due to its superior UV resistance.

Also, PETG struggles in high-temperature applications. Its lower heat resistance means it softens or deforms when exposed to significant thermal stress, making it unsuitable for components near heat sources or parts used in high-temperature environments.

For example, car interior parts that are exposed to direct sunlight or components placed near an engine or heating system could warp or deform. For projects requiring intensive heat, ASA’s thermal stability provides a more dependable solution.

In addition, when exposed to low temperatures to sub zero conditions, PETG may become brittle. If you need parts for freezers, cold storage units, and such, PETG will not be the right choice.

Which Is The Better Filament, ASA or PETG?

There is no filament that’s universally “better.” When it comes to choosing between ASA and PETG, the decision ultimately boils down to your project’s specific requirements. Understanding the strengths and limitations of each material ensures that you’re equipped to select the right filament for your needs.

Remember, the key to a successful print isn’t just about the filament—it’s about knowing how to leverage its properties to meet the demands of your project. Dialing in the right settings and making informed material choices is what separates good prints from great ones.