What filament is used in 3D printing?

Quick Answer: The Most Common 3D Printing Filaments

What is 3D Printing Filament, Anyway?

Before we dive into the nitty-gritty of each material, let’s clear up a fundamental point. When we talk about the most common type of 3D printing—the kind you see in schools, workshops, and homes worldwide—we’re talking about Fused Deposition Modeling (FDM), sometimes also called Fused Filament Fabrication (FFF).

This process works exactly like a high-tech, robotic hot glue gun. It takes a long, thin strand of plastic called filament, pulls it into a heated nozzle, melts it to a precise temperature, and extrudes it layer by layer to build an object from the ground up.

The filament is the “ink” for this process. It’s not just a simple plastic string; it’s a highly engineered thermoplastic, manufactured to an incredibly tight diameter tolerance, with specific additives for color and performance, and wound perfectly onto a spool.

How is This “Plastic Spaghetti” Actually Made?

Understanding how filament is made gives you an appreciation for why quality matters. The process is called extrusion.

1. Start with Pellets: It all begins with a hopper full of raw plastic pellets—tiny beads of a specific polymer like PLA or PETG. This is also where colorants and other performance-enhancing additives are mixed in.
2. Melt and Extrude: The pellets are fed into a long, heated barrel with a screw inside. The screw pushes the melting plastic forward, mixing it thoroughly and building pressure. At the end of the barrel is a die—a nozzle with a precise circular opening (e.g., 1.75mm). The molten plastic is forced through this die, emerging as a continuous strand.
3. Cooling and Measurement: This is the critical part. As the filament strand emerges, it passes through a cooling path (often a water bath) and then past a laser micrometer. This laser continuously measures the diameter of the filament. If it deviates even slightly from the target, it sends feedback to the extruder to adjust the speed, ensuring the diameter stays consistent. This is why cheap filament is often a bad deal—poor diameter consistency will cause jams and clogs in your printer.
4. Spooling: Finally, a machine pulls the cooled, measured filament at a constant rate and winds it neatly onto a spool, ensuring there are no tangles or snags.

When you buy a high-quality spool of filament, you’re paying for the purity of the raw material and the precision of this entire process.

Why is 1.75mm the Standard Diameter?

You’ll notice that the vast majority of printers on the market use 1.75mm diameter filament. There’s also a less common 2.85mm (often called “3mm”) standard. Why the difference, and why did 1.75mm win?

It comes down to a few key engineering principles:

• Precision: Melting a smaller-diameter rod gives you finer control over the volume of plastic being extruded. This allows for more precise starts and stops (retractions), leading to cleaner prints with less oozing.
• Flexibility: 1.75mm filament is more flexible, making it easier to route through the complex tube systems (called “Bowden” tubes) found on many modern printers. The stiffer 2.85mm filament requires wider, gentler curves to avoid snapping.
• Melt Speed: It takes less energy and time to melt a 1.75mm rod than a 2.85mm rod, allowing for faster response times in the hotend.
• Mechanical Force: The extruder gear that pushes the filament needs less force to push a 1.75mm filament, allowing for smaller, lighter motor assemblies, especially on “direct drive” systems where the motor rides on the print head.

While 2.85mm filament is still used on some excellent machines (notably those from Ultimaker and LulzBot), the market has overwhelmingly consolidated around the 1.75mm standard for its flexibility and precision.

What is the “King” of All Filaments for Beginners? (PLA)

If you are just starting your 3D printing journey, you will start with Polylactic Acid (PLA). Full stop. It is the undisputed king of hobbyist 3D printing for a reason: it is incredibly forgiving and easy to work with.

What Makes PLA So Easy to Use?

PLA is derived from renewable resources like corn starch or sugarcane. It’s a bioplastic, which gives it some unique properties that make it perfect for beginners.

• Low Printing Temperature: PLA prints at relatively low temperatures (around 190-220°C). This means almost any 3D printer on the market can handle it, and it puts less stress on the printer’s components.
• Minimal Warping: Warping is the boogeyman of 3D printing, where the corners of a print lift off the build plate as they cool. PLA has a very low thermal shrinkage rate, meaning it barely warps. You can often print it without a heated bed at all, which was a huge selling point in the early days of budget printers.
• Pleasant Smell: Because it’s plant-based, it emits a faint, sweet, almost waffly smell when printing. This is a stark and welcome contrast to the harsh chemical smells of other plastics.
• Great Detail: PLA can be cooled very quickly, which allows it to hold extremely fine details. It solidifies almost instantly after leaving the nozzle, resulting in sharp corners and crisp features, making it a favorite for printing things like tabletop miniatures.

Where Does PLA Shine?

Think “visuals over function.” PLA is the go-to material for:

• Decorative Objects: Vases, sculptures, and art pieces.
• Tabletop Miniatures: The level of detail PLA can capture is exceptional.
• Rapid Prototypes: Need a quick physical model to check the size, shape, and feel of a part? PLA is the fastest and cheapest way to do it.
• Non-Functional Parts: Jigs, templates, and organizers that won’t be subjected to heat or high stress.

What are PLA’s Biggest Weaknesses?

The properties that make PLA easy to print are also the source of its biggest weaknesses.

• Low Heat Resistance: This is its Achilles’ heel. PLA has a very low glass transition temperature (around 60°C or 140°F). This means on a hot summer day, a PLA part left in your car’s dashboard will warp into a sad, droopy mess. It is absolutely not for parts that will be used in or near engines, hot electronics, or even outdoors in direct sunlight in a hot climate.
• Brittleness: While it’s a very hard and rigid material, PLA is also quite brittle. It doesn’t bend; it shatters. If you need a part that can absorb impacts or flex without breaking, like a protective case or a snap-fit enclosure, PLA is a poor choice.

What is the “Tougher, More Resilient” Upgrade? (PETG)

Once you’ve mastered PLA and you start wanting to print parts that do something, you’ll inevitably graduate to Polyethylene Terephthalate Glycol (PETG).

Think of the plastic used for water bottles and soda bottles—that’s PET. PETG is a modified version (with the “G” for Glycol) that makes it clearer, less brittle, and easier to 3D print. It’s the perfect middle-ground material.

What Makes PETG a “Best of Both Worlds” Material?

PETG takes some of the best qualities of PLA and combines them with some of the strength of more industrial plastics like ABS.

• Good Strength & Durability: Unlike PLA, PETG has excellent layer adhesion and is much less brittle. It has a bit of flex, so it can absorb impacts and bend without shattering. This makes it ideal for mechanical parts.
• Better Temperature Resistance: PETG’s glass transition temperature is around 80°C (175°F), significantly higher than PLA’s. It will survive in a hot car and is suitable for parts that might be near warm (but not scorching hot) electronics.
• Chemical Resistance: It holds up well against many common chemicals, acids, and bases.
• Relatively Easy to Print: While it requires a heated bed and slightly higher temperatures than PLA (around 230-250°C), it has very low shrinkage, similar to PLA. This means it doesn’t warp easily, making it far simpler to print than ABS.

Where is PETG the Go-To Choice?

If PLA is for “looks,” PETG is for “looks and function.”

• Functional Parts: This is PETG’s kingdom. Brackets, mounts, printer upgrade parts, and mechanical components are all perfect applications.
• Protective Components: Its impact resistance makes it great for things like drone frames or protective covers for electronics.
• Snap-Fit Designs: Because it has some flex, PETG works well for parts that need to snap together.

What are the Downsides of PETG?

PETG is not without its quirks.

• Stringing: It has a tendency to be “goopy” and ooze from the nozzle, leaving fine, spiderweb-like strings on your prints. This can be managed with careful tuning of your printer’s settings (specifically retraction), but it rarely prints as cleanly as PLA.
• Hygroscopic: PETG absorbs moisture from the air. If filament gets “wet,” the water will flash to steam in the hot nozzle, causing pops, crackles, and weak, bubbly prints. For best results, it needs to be stored in a dry box or dried out before use.
• Scratches Easily: It’s a softer material than PLA and can be scratched more easily.

But what if you need a part that can withstand even higher temperatures or serious mechanical abuse? What if your part will live outdoors, exposed to the elements 24/7? For that, we need to move beyond the beginner-friendly plastics and into the world of true engineering-grade filaments. In the next part, we’ll cover the industrial workhorse ABS, its modern successor ASA, and other specialty filaments, and finally tackle the critical question: can you ever safely eat or drink from a 3D printed part?

What is the Original “Industrial Workhorse” of 3D Printing? (ABS)

Before PLA became the king of hobbyist printing, there was Acrylonitrile Butadiene Styrene (ABS). This is the same tough, impact-resistant plastic that LEGO bricks, car dashboards, and computer keyboard caps are made from. For a long time, if you wanted to 3D print a “real” part that could do a “real” job, ABS was your only option.

ABS is a true engineering thermoplastic, but all that strength comes at a cost. It is notoriously difficult to print with, and it’s the material that has caused more beginners to give up in frustration than any other.

What Makes ABS So Strong, and So Difficult?

ABS is an amorphous terpolymer, meaning it’s built from three different monomers:

• Acrylonitrile: Provides chemical resistance and thermal stability.
• Butadiene: A rubbery polymer that provides toughness and impact strength. This is the “B” that puts the “tough” in ABS.
• Styrene: Provides a glossy finish and rigidity.

This cocktail of chemicals gives ABS its desirable mechanical properties, but it also creates a perfect storm of printing challenges.

• High Printing Temperature: ABS requires high nozzle temperatures (240-260°C) and, crucially, a high bed temperature (100-110°C). Many entry-level printers cannot safely reach these temperatures.
• Extreme Warping: This is the number one killer of ABS prints. ABS has a very high coefficient of thermal expansion, meaning it shrinks significantly as it cools. As the upper layers of your print cool and shrink, they pull on the bottom layers, causing the corners to curl up and lift dramatically off the build plate.
• Toxic Fumes: The “Styrene” component releases noxious and potentially harmful fumes (Volatile Organic Compounds or VOCs) when melted. Printing ABS absolutely requires excellent ventilation and is not something you want to do in a small, enclosed living space.
• Requires an Enclosure: The only reliable way to combat warping is to print ABS inside a heated chamber or enclosure. This keeps the ambient temperature around the part high and stable, preventing the drastic temperature changes that cause shrinking and warping.

So, Why Would Anyone Still Use ABS?

With all those downsides, why hasn’t ABS disappeared? Because for certain applications, it’s still the best tool for the job.

• Superior Temperature Resistance: With a glass transition temperature of around 105°C (221°F), ABS is a significant step up from PETG. It’s the go-to choice for parts that will live in hot environments, like custom fan shrouds for your 3D printer’s hotend or interior car parts.
• Acetone Vapor Smoothing: This is ABS’s killer feature. You can expose an ABS print to acetone vapor, which melts the outer surface of the part. This process completely erases the layer lines, resulting in a smooth, glossy, injection-molded appearance. It also significantly strengthens the part by chemically welding the layers together.
• Machinability: ABS is much better suited to post-processing than PLA or PETG. It can be easily sanded, drilled, tapped, and even machined without melting or cracking. This is where the worlds of additive and subtractive manufacturing can meet. If you need a near-net shape that you’ll finish with a drill press or a milling machine, ABS is often a better starting point than other plastics.

If you have a project requiring a custom-shaped jig or fixture with complex internal channels that would be impossible to machine from a solid block, you could 3D print it in ABS and then send it to a service like ours to have the critical mating surfaces or threaded holes machined to a perfect tolerance. This hybrid approach combines the geometric freedom of 3D printing with the precision of CNC machining.

Is There a “Modern, Better” Version of ABS? (ASA)

For years, the choice was either easy-but-brittle PLA or strong-but-difficult ABS. The community desperately needed a material with the strength of ABS but the printability of PLA. While PETG filled part of that gap, the true successor to ABS is Acrylonitrile Styrene Acrylate (ASA).

Think of ASA as ABS’s highly-engineered cousin. It was specifically designed for outdoor applications in the automotive and construction industries. It keeps all the good things about ABS and fixes its biggest flaw.

How Does ASA Outperform ABS?

ASA’s key advantage is its exceptional UV and weather resistance.

ABS has a major weakness: the Butadiene component is quickly broken down by UV radiation from sunlight. An ABS part left outdoors will become yellow, chalky, and extremely brittle in a matter of months.

ASA replaces the vulnerable Butadiene rubber with an Acrylate rubber, which is virtually immune to UV radiation and weathering. This makes ASA the undisputed champion for any part that will live its life outdoors.

• Weatherproof: Rain, sun, heat, cold—ASA can handle it all without degrading.
• Similar Strength to ABS: It retains the high impact resistance and temperature tolerance (around 100°C) of ABS.
• Slightly Easier to Print: While it still requires an enclosure and high temperatures, most users find ASA warps slightly less and releases less noxious fumes than ABS. The smell is still present but is generally considered less offensive.
• Acetone Smoothing: Yes, like ABS, it can also be vapor smoothed for a glossy, layer-free finish.

Where Should I Choose ASA Over Other Filaments?

If your part is going outside, use ASA. It’s that simple.

• Outdoor Fixtures: Garden hose brackets, custom sprinkler heads, satellite dish mounts, bird feeders.
• Automotive Exterior Parts: Custom replacement trim pieces, brackets for auxiliary lights, or aerodynamic components.
• Scientific Equipment: Housings for weather stations or outdoor sensor arrays.
• Anything that needs ABS-level strength but will be exposed to sunlight.

The main downside is cost. ASA is typically more expensive than ABS, so for indoor-only parts, it’s often overkill.

What About Flexible, Rubbery Parts? (TPU)

So far, we’ve only talked about rigid plastics. But what if you need to print something soft and squishy, like a phone case or a flexible seal? For that, you need Thermoplastic Polyurethane (TPU).

TPU is a thermoplastic elastomer, a class of plastics that behave like rubber. It’s incredibly durable, abrasion-resistant, and flexible.

The Challenge and Reward of Printing TPU

Printing TPU is a unique experience. Imagine trying to push a wet noodle through a small tube—that’s the challenge.

• Requires a “Direct Drive” Extruder: Because the filament is so flexible, it will bend and buckle if there’s any unsupported space between the extruder gear and the hotend. Printers with a “Bowden” setup (where the extruder is mounted on the frame and pushes the filament through a long tube) struggle mightily with TPU. A “direct drive” setup, where the extruder sits directly on top of the hotend, is highly recommended for a pain-free experience.
• Slow Printing Speeds: You must print TPU very, very slowly (often 20-30 mm/s) to give it time to extrude without kinking or jamming.
• Moisture is the Enemy: Like PETG and Nylon, TPU is extremely hygroscopic and must be kept perfectly dry for good results.

The reward for this careful process is a part with incredible properties. TPU has fantastic layer adhesion, creating parts that are almost indestructible. You can run them over with a car, and they’ll just bounce back.

Where Does TPU Excel?

• Protective Cases: Phone cases, GoPro bumpers, and protective feet for electronics.
• Seals and Gaskets: Custom-shaped gaskets for airtight or watertight enclosures.
• Vibration Dampeners: Soft motor mounts or feet for printers and other machinery to reduce noise.
• Wearables: Flexible watch bands or custom shoe insoles.

TPU’s flexibility is measured on the Shore Hardness scale. A very flexible filament like 85A is like a rubber band, while a semi-flexible 95A is stiffer, more like the sole of a running shoe. Most hobbyists start with 95A as it’s a bit easier to print.

The Ultimate Question: Is Any 3D Printed Part “Food Safe”?

This is one of the most common and most important questions in the 3D printing community. You’ve just printed a cool-looking cookie cutter or a custom coffee mug. Can you actually use it?

The short answer is no, you should not consider a raw 3D printed part from a hobbyist FDM printer to be food safe.

The long answer is more nuanced and explains the multiple reasons why.

Are There Any Exceptions?

So, is it impossible to make a food-safe part? Not impossible, but it requires significant post-processing.

1. Use a Known Food-Grade Filament: Start with a natural, uncolored PETG from a reputable manufacturer that certifies the raw resin as food-grade.
2. Use a Stainless Steel Nozzle: This eliminates the risk of lead contamination from the nozzle.
3. Coat the Part: The only reliable way to make an FDM print food-safe is to seal the surface, eliminating the layer lines. This must be done with a certified food-safe coating, such as a two-part epoxy resin that is rated for food contact. The part must be completely and perfectly coated, with no pinholes or gaps.

For one-off, non-critical items like a cookie cutter that will only be used with dough and then immediately hand-washed, the risk is very low. But for anything that will hold liquids or be used repeatedly, especially with wet foods, the risk of bacterial growth is too high without a proper food-safe coating. Never drink hot liquids from a raw 3D printed mug, as the heat can accelerate the leaching of chemicals from the plastic.

The journey through the world of 3D printing filaments is one of trade-offs. There is no single “best” filament, only the “best” filament for a specific job. By understanding the unique strengths and weaknesses of each material—from the easy-printing but brittle PLA to the tough but finicky ABS and its weatherproof successor ASA—you can unlock the true potential of your 3D printer and choose the perfect material to bring your ideas to life.

Further Reading & Resources

• All3DP – The Best 3D Printer Filament Types: A comprehensive and constantly updated guide to all the major and exotic filament types on the market.
• PrusaPrinters – Material Guide: An excellent series of articles from one of the leading printer manufacturers, detailing the properties and best practices for printing each common material.
• MatterHackers – “How to Succeed with PETG”: A deep-dive article on the specifics of taming PETG and getting perfect prints.
• FDA – “Food Contact Substance Notification Program”: The primary source for understanding the regulations and requirements for a material to be considered food safe in the United States.

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