PETG vs ASA — parameter comparison and when to choose which

The decision in one sentence: PETG you can print on whatever you already have, ASA needs an enclosed chamber — so the question is whether the part really has to survive more than 85 °C and a whole summer outdoors, because only that justifies buying more hardware.

A camera bracket on a facade, a sensor housing by the gate, a key box, a rail holding a panel on a carport roof. These are the specific jobs that make someone start looking for the difference between PETG and ASA. The manufacturer Porima's official FDM table has the same fields filled in for both, and it shows an unusual situation: ASA wins on the things that matter outdoors, and loses on every one that concerns the printing itself.

Comparison table

Parameter	PETG	ASA
Nozzle temperature	240–260 °C	250–280 °C
Bed temperature	60–80 °C	90–120 °C
Cooling	100%	0–30%
Drying	2–4 h / 30–40 °C	6–12 h / 40–60 °C
Chamber enclosure	open frame	enclosed chamber, 50 °C
Temperature resistance	85 °C	110 °C
Print difficulty	easy	medium
Warping	none	medium
Stringing	high	medium
Layer cohesion	very good	good
Impact resistance	high	high
Flexibility	high	high
Surface finishing	medium	easy
Support removal	medium	easy
Odour	very low	medium
Nozzle abrasiveness	none	none
Print speed	high	high
Finish	glossy, translucent	matte, opaque
Compatible printers	any desktop FDM	enclosed only
Bambu AMS	compatible	not recommended

A highlighted cell marks the material that is clearly better in that row. Where the values are identical there is no winner. Source: the official FDM technical data table from the manufacturer, Porima. Full data sets: PETG print parameters · ASA print parameters.

When to choose PETG

Anything that works under cover or indoors. Guards, guides, brackets in the garage and the workshop. A declared 85 °C is enough everywhere there is no direct sun.

Parts that have to let light through. Diffusers, LED covers, sight glasses. ASA is listed in the table as "opaque" and no settings will get you round that.

Parts working under a bending load. Layer cohesion "very good" against "good" for ASA. A hinge, a clip, a sprung catch — PETG holds its layers together more firmly.

Anything you print on an open machine in a flat or an office. Open frame, odour "very low", AMS compatibility. ASA has no business being used in those conditions.

Short production runs to order. Difficulty "easy" and no warping mean a predictable turnaround, and when you are selling prints that counts for more than the extra 25 °C of resistance.

When to choose ASA

Brackets and housings mounted on the outside of a building. Camera mounts, sensor covers, antenna fixings. That is the main reason ASA exists in the catalogue.

Parts lying in full sun through the summer. A fitting on an external window sill, a bracket on a balcony, a part on a trailer roof. A declared 110 °C gives headroom over PETG.

Car parts mounted on the outside of the bodywork or in the engine bay. The higher 90–120 °C bed range and the enclosed chamber are the price, but it is the only sensible choice of the two.

Parts that will be sanded, filled and painted. Surface finishing "easy" against "medium" for PETG. ASA's matte surface takes primer without any degreasing heroics.

Models with a lot of supports. Support removal "easy" for ASA and "medium" for PETG — with PETG the supports can weld themselves to the model.

What the table won't tell you

The manufacturer's table has no UV resistance field. We say that plainly, because it is the most important sentence on this page. In 3D printing ASA is the material people reach for in outdoor applications, but Porima publishes neither a figure nor a test method for resistance to sunlight — and we will not quote a value that is not in the source. The only thing we can set side by side honestly is 110 °C against 85 °C, and in this table that is the argument for ASA outdoors.

85 °C and 110 °C are the manufacturer's labels, not HDT. There is no standard or described test procedure behind them. They do not mean the part will hold its shape under load at that temperature — they mean only that above it the material starts behaving differently. For a responsible application, print the part and leave it out for a few weeks in the place it is meant to work.

"Bambu AMS: not recommended" for ASA does not mean the material is bad. It means it should not be run through the AMS system. ASA is printed from an external holder, in an enclosed machine — it is a question of the filament path and the conditions in the chamber, not of spool quality.

"Medium" warping on ASA is gentler than on ABS, but it is not zero. A large flat part will lift at the corners despite a correct chamber if there is a draught in the room. With PETG that problem simply does not occur, and that is a difference you feel in the workshop schedule rather than in the part's specification.

"High" stringing on PETG can be solved with settings; temperature resistance cannot. The stringing will drop once you dry the spool and lower the nozzle by 5 °C. The missing 25 °C of resistance cannot be printed in with any profile. If the decision really is about working outdoors, that is the one row that outweighs the whole rest of the table.

Where to check this further

• Filament comparison — which material to choose for what — the hub for all ten pair comparisons plus the main table of twelve material families.
• PETG print parameters — the complete set of fields from the manufacturer's table.
• ASA print parameters — chamber, bed and cooling ranges.
• Stringing — compulsory with PETG.
• Warping — the first problem with ASA and with every material that needs a chamber.
• Wet filament — ASA needs 6–12 h of drying, PETG 2–4 h.
• Marks left by supports — this is where the difference in support removal shows.

Materials to buy: Porima PETG filament 1 kg and Porima ASA filament 1 kg.