PLA, PETG, ABS or TPU: Which Filament Should You Actually Use?

Walk into any filament shop and you'll find a dozen materials, all promising to be stronger, tougher or more heat-resistant than the last one. For almost everything you will ever print, four of them cover the ground: PLA, PETG, ABS and TPU. Here's what each one is actually good at, and — more usefully — what each one is bad at. The short version PLA PETG ABS / ASA TPU Nozzle 190–220 °C 230–250 °C 230–260 °C 220–235 °C Bed 55–65 °C 70–85 °C 100–110 °C 40–60 °C Enclosure No Helpful Effectively required No Softens at ~60 °C ~80 °C ~105 °C Varies Difficulty Easy Moderate Hard Moderate Breaks by Snapping Bending Bending Doesn't Treat these numbers as starting points, not gospel. Brands vary, and the spool label is more authoritative than any table on the internet — but the label is often a wide range, and these are sensible places to begin inside it. PLA: use it unless you have a reason not to PLA is the default for good reason. It prints at low temperatures, barely warps, doesn't smell, doesn't need an enclosure, and holds fine detail better than anything else on this list. If you're printing something decorative, something you're testing, or anything that lives indoors and doesn't take load, use PLA. It is also stiffer than most people expect. PLA has a higher tensile strength than PETG on paper. What it lacks is toughness: it resists being pulled, but it snaps rather than bends when you overload it. Drop a PLA part on a tiled floor and it shatters; the same part in PETG bounces. The thing that catches everybody out is heat. PLA starts to soften around 60 °C. That sounds high until you leave a print on a car dashboard in summer, and come back to a sculpture. A closed car in the sun comfortably exceeds 60 °C. So does the inside of a window sill in July, a spot next to a radiator, and the top of a 3D printer's own power supply. If the part will sit in a hot place, PLA is the wrong answer, and this is the single most common material mistake beginners make. Good for: decorative prints, figurines, prototypes, cake toppers, indoor signs, boxes and organisers, anything you'll print once and look at. Bad for: car interiors, anything outdoors in summer, mechanical parts under load, anything that gets dropped. PETG: the practical middle ground PETG is what you move to when PLA breaks. It's tougher, more flexible before it fails, holds up to about 80 °C, resists water and UV reasonably well, and is a genuinely good outdoor material. It's the same family of plastic as drinks bottles. It is meaningfully fussier to print, in three specific ways. It strings. PETG likes to leave fine hairs between parts of a model. This is mostly curable — lower the nozzle temperature in 5 °C steps, increase retraction distance, and dry the filament — but expect to spend an evening calibrating rather than getting perfect results out of the box. It sticks to the plate too well. This sounds like a good problem and isn't. PETG bonds chemically to smooth PEI and to glass, strongly enough to tear the coating off the plate when you remove the part. The fix is to put a thin layer of ordinary glue stick down first — not as adhesive, but as a release layer that stops direct contact. Textured PEI is generally safe without it. It absorbs water fast. A spool left open in a humid room for a few weeks will print visibly worse — popping sounds, rough surfaces, more stringing. Keep PETG sealed with desiccant between prints. One more thing worth knowing: PETG doesn't bond as well between layers as it does to itself in a single layer, and it can be surprisingly weak against splitting along layer lines. Print important parts with more walls rather than more infill. Good for: functional parts, brackets, outdoor items, planters, things that flex slightly, phone stands, anything that needs to survive a drop. Bad for: fine detail (it rounds off crisp edges), your first ever print, anything where stringing would ruin the look. ABS and ASA: only with an enclosure ABS is what injection-moulded consumer goods are made of — Lego, car trim, tool housings. It's tough, machinable, holds up past 100 °C, and can be smoothed to a glossy finish with acetone vapour, which nothing else here can do. It also warps aggressively. As ABS cools it shrinks, and that shrinkage pulls the corners of your print off the plate with real force. Printing ABS on an open printer in a normal room means large parts will lift, split partway up, or simply fall off. An enclosure isn't a nice-to-have; it's the thing that makes ABS work. Ventilation matters too. ABS releases styrene and ultrafine particles while printing, with a distinct sharp smell. Print it in a ventilated space — not a bedroom, not a closed office you're sitting in. If your printer has a filtered enclosure, use it. ASA is ABS's better-behaved cousin. Very similar temperatures and handling, slightly less warping, and much better UV resistance. If a part is going to live outside in the sun, ASA holds its colour and strength where ABS goes chalky and brittle. For most people, if you're reaching for ABS, ASA is the better choice. Good for: car parts, tool holders, anything near heat, parts you want to sand and paint, outdoor items in direct sun (ASA). Bad for: open printers, unventilated rooms, large flat parts, anyone who wants a quiet life. TPU: flexible, and slower than you think TPU is rubber. You can bend it, squash it, and it springs back. It's sold by hardness on the Shore scale — 95A is the common general-purpose grade and roughly the firmness of a shoe sole. Lower numbers (85A) are floppier and much harder to print; higher numbers (98A, or Shore D grades) are stiffer and more forgiving. The main thing to understand is that you cannot push a flexible filament fast. The extruder is trying to shove a piece of rubber down a tube, and rubber compresses instead of pushing. Print TPU at 20–30 mm/s. Faster than that and the filament buckles inside the extruder and jams. Direct drive extruders handle TPU much better than Bowden setups, because the filament has a shorter unsupported path. You can print TPU on a Bowden printer, but expect more trouble and softer grades to be nearly impossible. Two more practical notes: use little or no retraction, since retracting a rubber string just stretches it; and dry your TPU, because it absorbs moisture even faster than PETG. Good for: phone cases, gaskets and seals, watch straps, tyres and wheels, protective bumpers, anything that needs to grip. Bad for: anything rigid, fast printing, fine detail, Bowden printers with soft grades. How to actually choose Rather than memorising the table, ask three questions about the part: Will it get hot? Above 50 °C — in a car, in direct sun, near a motor or a light — PLA is out. Go PETG, or ASA if it's outdoors and sunny. Will it take load or get dropped? If a crack would matter, PETG over PLA. PLA is fine for things that sit still. Does it need to bend? Then TPU, and only TPU. Nothing else on this list flexes usefully. If all three answers are no — and for most of what people print, they are — use PLA. It's cheaper, easier, prints faster, looks better, and you'll finish the job today instead of calibrating all evening. The one habit that helps with all of them Keep your filament dry. Every material here absorbs water from the air, some of them fast, and wet filament produces bad prints in ways that look like a dozen other problems: stringing, popping noises, weak layers, rough surfaces, inconsistent extrusion. People spend weeks tuning retraction settings to fix problems that a night in a dryer would have solved. Sealed boxes with silica gel are cheap. A filament dryer is better. Either beats troubleshooting the wrong thing.

Why Your First Layer Won't Stick

Almost every failed print fails in the first two minutes. The nozzle lays down a line, the line curls up behind it, and forty minutes later you come back to a plate covered in what the internet affectionately calls spaghetti. The good news: first layer problems have a short list of causes, and you can work through all of them in about five minutes. The trick is knowing what to look at first. Start by learning what a good first layer looks like Before you change any settings, print something and look at it. This one skill will save you more time than any setting in your slicer. A good first layer has three properties: The lines touch each other. No gaps between them. The surface should look solid, like a sheet, not like a row of parallel worms. The lines are slightly flattened. A round line means the nozzle was too far from the plate. You want the plastic squashed a little, so it has somewhere to grab. You can't easily lift a corner with your fingernail. If a corner pops up while the print is still running, it will keep going. If your first layer looks like separate round strands with gaps between them, your nozzle is too high. That's the single most common cause, and it's the first thing to check. If the layer looks scratched, translucent, or has ridges where the plastic was pushed sideways, your nozzle is too low. This causes its own problems — it can clog the nozzle and leave a flared "elephant's foot" at the base of your model. The five-minute checklist Work through these in order. Stop when the problem goes away. 1. Check your Z-offset This is the distance between the nozzle tip and the plate on the first layer, and it's wrong more often than anything else. The classic method: heat the bed to printing temperature, put a sheet of ordinary printer paper (about 0.1 mm thick) under the nozzle, and adjust until you feel slight drag when you pull the paper. Not free-sliding, not stuck — a light scrape. Most modern printers let you adjust the Z-offset live, while the first layer is printing. This is by far the easiest way to do it. Start a print, watch the lines, and nudge the offset down in steps of 0.01–0.02 mm until the lines stop being round and start touching each other. Do this with the bed hot. Metal expands, and a plate levelled cold will not be level at 60 °C. 2. Clean the plate Fingerprints are grease, and nothing sticks to grease. If you've picked the plate up with bare hands — and everyone does — that's very likely your problem. Wash it in the sink with warm water and ordinary dish soap, then dry it with a clean cloth or paper towel. This works better than isopropyl alcohol, which spreads thin films of oil around as much as it removes them. Use alcohol for a quick touch-up between prints, and soap and water properly every week or two. After cleaning, handle the plate by the edges. One warning: if you have a textured PEI plate, don't scrub it with anything abrasive. The texture is the adhesion. 3. Check your bed temperature Cold plastic doesn't stick. Rough starting points: Material Bed temperature PLA 55–65 °C PETG 70–85 °C ABS / ASA 100–110 °C TPU 40–60 °C If you're at the low end and struggling, add 5–10 °C. Many slicer profiles also run the first layer a few degrees hotter than the rest of the print, which is worth doing. Bear in mind that the number on your screen is what the sensor reads, usually near the heater, not necessarily what the surface is doing. A cheap infrared thermometer or a bed thermistor test will tell you if your plate reads 60 and delivers 48. 4. Slow down the first layer The first layer is the one layer with nothing underneath it to hold the plastic in place. Print it slowly — around 20–25 mm/s — even if the rest of the print runs at 60 or 200. Fast first layers drag plastic instead of laying it down. If your prints stick fine on small parts but fail on big ones, speed is a likely suspect. 5. Turn the part cooling fan off for layer one Cooling is what gives you crisp overhangs later in a print. On the first layer it does nothing but cool the plastic before it can bond to the plate. Almost every slicer has a setting for this. Fan off for layer 1, then ramp up from layer 2 or 3. For ABS and ASA, keep the fan off or very low for the whole print. 6. Use a sensible first layer height With a standard 0.4 mm nozzle, a first layer of 0.2 mm is forgiving and reliable. Going down to 0.12 mm gives you a slightly nicer bottom surface and a much less reliable print, because it leaves no margin for a plate that isn't perfectly flat. If you're fighting adhesion, set the first layer to 0.2 mm or even 0.25 mm and stop worrying about it. When the settings are fine and it still won't stick Small footprints A model that touches the plate on four tiny points has almost nothing to grab with. Add a brim — a flat skirt of material attached to the base of the model, usually 5–8 mm wide. It peels off afterwards with a fingernail or a deburring tool. A brim solves more adhesion problems than any other single setting, and costs almost no material or time. Warping If a print sticks fine at first and then lifts at the corners partway through, that's not adhesion — that's warping. The plastic is shrinking as it cools and pulling itself off the plate. Warping is mostly about temperature stability. Move the printer away from open windows, doors and air conditioning. A draught across a print is enough to lift a corner. ABS and ASA warp badly enough that they realistically need an enclosure; PLA rarely warps at all; PETG sits in between. The wrong surface for the material Different plates suit different materials: Textured PEI is the most forgiving all-rounder, and leaves a pleasant matte finish on the bottom. Smooth PEI gives a glossy bottom and grips PLA extremely well — sometimes too well. Glass needs help: a thin layer of glue stick, or hairspray. That "too well" is a real issue. PETG bonds to smooth PEI and glass so strongly that it can rip chunks out of the plate when you remove the part. The standard fix is counterintuitive: put a thin layer of ordinary glue stick down first, as a release agent. It stops PETG bonding directly to the surface. A worn plate PEI sheets don't last forever. If the middle of your plate — where you print everything — has stopped gripping while the edges still work, the coating is worn. Most plates are double-sided, so flip it over and carry on. Wet filament won't fix itself If you're getting popping and hissing noises from the nozzle, visible steam, or a rough, bubbly surface, your filament has absorbed moisture from the air. Wet filament makes weak, ugly first layers regardless of how well levelled your plate is. PLA is fairly tolerant. PETG and TPU absorb water quickly — a spool left open on a shelf for a month in a humid climate is measurably worse than a fresh one. You can dry filament in a dedicated dryer, or in an oven at low temperature if you can trust it to hold 45–55 °C without spiking. Don't put PLA above about 50 °C — it will soften and fuse on the spool. Store spools with silica gel in a sealed box, and the problem mostly disappears. A short summary If your first layer isn't sticking, in order: Look at the lines — round and separated means the nozzle is too high Adjust the Z-offset live while printing, with the bed hot Wash the plate with soap and water Raise the bed temperature 5–10 °C Slow the first layer to 20–25 mm/s Turn the fan off for layer one Add a brim Nine times out of ten, it's the first three. Get in the habit of watching the first layer go down instead of walking away, and you'll catch failures in thirty seconds instead of forty minutes.