PLA vs PETG vs ABS vs ASA: Which Filament Does Your Part Actually Need?

Most filament comparisons are tables of tensile strength figures. They're almost useless, for a reason that takes a moment to explain but changes how you choose materials forever.

Published tensile strengths come from injection-moulded test specimens. Your part isn't injection moulded. It's built from stacked layers, each thermally welded to the one below, and it's dramatically weaker across those layers than along them. A printed part typically reaches 60-80% of the datasheet figure in the strong direction and considerably less in the weak one.

So the datasheet number isn't a prediction of your part's strength. It's only useful for comparing materials to each other.

Which means the right question isn't "which material is strongest". It's "how would this part fail?", because that question has a different answer for each material, and the answer is actionable.

The one-line version

• PLA: cheapest, best detail, softens at 55 °C. Indoor, unloaded parts.
• PETG: tough, water-resistant, easy. The sensible default for functional parts.
• ABS: heat tolerant, acetone-smoothable, needs an enclosure. Parts that get warm.
• ASA: ABS that survives sunlight. The only correct outdoor choice.

If you read no further: use PETG unless you've a specific reason not to. It's the right answer more often than anything else.

PLA: the one everybody starts with

PLA is polylactic acid, made from corn starch. It prints at low temperatures, barely warps, holds fine detail better than anything else in this list, and it's the cheapest thing on the shelf at around ₹6.5 per cm³.

Its problem is heat. PLA's glass transition sits around 55-60 °C, and that's much lower than it sounds. A car parked in Maharashtra in May reaches 60-70 °C inside. A part on a windowsill in direct sun will get there. A bracket near a motor or a power supply will get there. When PLA reaches that temperature it doesn't melt dramatically. It goes soft and slowly deforms under whatever load is on it, and by the time you notice, the part has sagged out of tolerance.

PLA is also brittle. It's stiff and strong right up until it fails, and then it fails suddenly and completely rather than bending first. Drop a PLA part on a hard floor and it's more likely to shatter than to bounce.

Use PLA for: concept models, fit checks, display pieces, indoor organisers, anything cost-sensitive that lives at room temperature and doesn't get knocked.

Avoid PLA for: anything outdoors, anything in a vehicle, anything near heat, anything that gets dropped, anything structural.

PETG, the default you should probably be using

PETG is the same polyester family as drinks bottles, modified with glycol so it prints well. It sits between PLA and ABS on nearly every axis and it's the material we quote most often.

Its heat resistance is about 75 °C, not remarkable, but enough for most indoor and many outdoor-shade applications. It's considerably tougher than PLA: it bends before it breaks, which means a PETG part that's overloaded deforms and warns you rather than shattering. It's water-resistant, resists most household chemicals, and it doesn't need an enclosure.

Its weaknesses are honest ones. It's stringier to print than PLA, so fine detail and sharp corners come out slightly softer. It's somewhat prone to scratching. And it isn't UV stable, a PETG part in direct Indian sun will yellow and embrittle over a season or two.

At around ₹8 per cm³ it costs about 45% more than PLA, and that's close to the best value in the catalogue.

Use PETG for: functional prototypes, brackets, enclosures, jigs and fixtures, mechanical parts, anything that will be handled, and honestly most things.

Avoid PETG for: sustained direct sunlight, service above 75 °C, or optically clear parts where you need a glass-like finish.

ABS, heat resistance and the acetone trick

ABS is the classic engineering thermoplastic: LEGO bricks, car interior trim, appliance housings. It handles about 85 °C, machines and taps cleanly, and it accepts solvent bonding, which means two ABS parts can be chemically welded into what's effectively one piece.

Its party trick is acetone smoothing. Exposing an ABS part to acetone vapour dissolves the surface just enough for it to flow, erasing layer lines entirely and leaving a glossy, injection-moulded-looking finish. Nothing else on this list does that.

The catch is printing it. ABS shrinks significantly as it cools, and if it cools unevenly the part warps, corners lift off the plate, and layers separate, sometimes days after the print finished, in a crack that propagates straight through the wall. This is why ABS has a reputation for being difficult.

The fix is an enclosed chamber that keeps the ambient temperature high so the part cools slowly and evenly. Both of our machines are enclosed, which is the difference between "we can technically run ABS" and "we can run ABS on a part you intend to sell". If a shop is printing ABS on an open-frame machine, be sceptical.

At roughly ₹8 per cm³, ABS is marginally cheaper than PETG.

Use ABS for: parts that get warm, parts you want to solvent-bond, parts you want to smooth to a gloss finish, machinable and tappable components.

Avoid ABS for: outdoor use, large flat geometry prone to lifting, or anything where you can't guarantee an enclosed printer.

ASA: the outdoor answer

ASA is chemically ABS with the butadiene replaced by an acrylate. That single change buys genuine UV and weather stability, and it's the entire reason to choose it.

Everything else on this list degrades in sunlight. PLA embrittles and discolours within a season. PETG yellows. ABS chalks, fades and loses impact strength. You've seen this on old plastic garden furniture and faded car trim. ASA doesn't do this. It holds colour and mechanical properties for years outdoors, and in Indian sun that difference is dramatic rather than marginal.

It also handles about 90 °C, slightly better than ABS, and it acetone-smooths the same way. It prints much like ABS: enclosure required, same warping tendencies, same care needed.

It costs around ₹10 per cm³, roughly 40% more than ABS, and for anything living outside that premium isn't optional. It's the difference between a part that lasts and a part that fails.

Use ASA for: anything outdoors, anything in direct sun, automotive exterior parts, sensor housings, garden and rooftop equipment, signage.

Avoid ASA for: indoor parts where you're paying a UV premium for nothing.

Side by side

	PLA	PETG	ABS	ASA
Service temperature	55 °C	75 °C	85 °C	90 °C
Toughness	Brittle	Good	Good	Good
UV stability	Poor	Poor	Poor	Excellent
Detail quality	Excellent	Good	Good	Good
Needs enclosure	No	No	Yes	Yes
Acetone smoothing	No	No	Yes	Yes
Cost per cm³	₹6.5	₹9	₹8.5	₹12

Choosing by failure mode

Work through this in order and stop at the first match.

Will it sit in sunlight? → ASA. Nothing else survives UV, and no amount of the others' other virtues compensates.

Will it get above 75 °C? → ABS or ASA. If it will get above 90 °C, you need polycarbonate or PA-CF instead, which are outside this comparison.

Will it be dropped, struck or handled roughly? → PETG at minimum. Not PLA, which shatters. If impact is the main design risk, consider polycarbonate.

Do you need to smooth or solvent-bond it? → ABS or ASA.

Does it need the finest possible detail, fine text, crisp edges, small features? → PLA.

Is it a fit check or concept model that will be thrown away next week? → PLA, draft finish, low infill. Spend nothing.

None of the above? → PETG. This covers most parts.

The mistake we see most

Over-specification, by a wide margin. Someone reads that PA-CF is the strongest material available and specifies it for an indoor bracket carrying a phone. That part costs three times what it needs to and performs no better in its actual application.

The mirror-image mistake is worse but rarer: PLA specified for something that lives in a car or on a roof. That part doesn't merely underperform, it fails, usually a few weeks in, usually after the customer has already installed it.

Both mistakes come from thinking about materials in the abstract rather than about the specific ways a specific part might fail. Spend two minutes on the failure mode and the material chooses itself.

Getting a second opinion

Material selection consulting is free with every quote, and we use it more often to talk people down than up. If you tell us the part is an indoor bracket for a light load, we'll tell you PETG and decline to sell you the carbon fiber.

If you're unsure, describe the part's life, where it lives, what it touches, how hot it gets, what happens if it breaks, and we'll tell you which of these four to use, or whether you need something else entirely.