ABS and ASA

What they are good at

Prusa describes ABS as a technical material with high toughness and temperature resistance, suited to mechanically stressed parts, and lists LEGO-style bricks, car parts and phone parts as typical uses. ASA is its successor: Prusa rates it for outdoor use because of its high UV and temperature resistance, with less warping and less odor than ABS. Prusa notes that ABS parts left outdoors yellow and become more brittle over time.

	ABS	ASA
Heat	Good	Good; Prusa rates it up to 93 °C Rule of thumb
UV and outdoor use	Poor; yellows and embrittles	Good
Warping	Significant	Less than ABS, still the main problem
Odor and fumes	Styrene; more odor	Styrene; less odor than ABS
Acetone	Smooths and glues	Smooths, glues and welds

Polymaker's data supports the heat claims for its products: PolyLite ABS has a glass transition of 101 °C and Polymaker ASA 98 °C Maker spec, well above PLA's 61 °C in the same maker's data. ABS is also the less brittle of the two in Polymaker's figures, with elongation at break along the layers of about 18 percent for PolyLite ABS against about 7 percent for Polymaker ASA Maker spec. Across layers the figures drop to about 3 percent for PolyLite ABS and under 2 percent for Polymaker ASA Maker spec.

Two makers, two sets of numbers

Setting	Prusa	Polymaker TDS
ABS nozzle	255 °C (its ABS profile) Starting point	PolyLite ABS: 245 to 265 °C Maker spec
ABS bed	100 °C; 80 to 110 °C, hotter for big parts Starting point	PolyLite ABS: 90 to 100 °C Maker spec
ASA nozzle	Prusa's ASA guide: 260 °C Starting point	Polymaker ASA: 230 to 260 °C Maker spec
ASA bed	Prusa's ASA guide: 105 °C first layer, 110 °C after Starting point	Polymaker ASA: 75 to 95 °C Maker spec
Cooling fan	Not specified	Off Maker spec
Enclosure	Prusa lists an enclosure as required for ABS; for ASA, necessary for large parts	Closed chamber needed, for both Maker spec

The ranges overlap but do not match; Prusa's suggested ASA bed temperature sits above Polymaker ASA's whole range. Use the figures for the spool you actually have, then run a temperature tower.

Warping, shrinkage and the enclosure

Prusa explains warping as the result of temperature differences between the model and its surroundings. The fix is to keep the air around the print warm: print inside an enclosure, keep the bed hot (Prusa says at least 100 °C for both materials Starting point), and avoid drafts. Without an enclosure, PrusaSlicer's draft shield (under Skirt and brim) builds a thin wall that keeps the model slightly warmer. Prusa calls an enclosure necessary for large ASA parts.

Prusa notes ABS parts usually shrink around 1 to 2 percent after cooling Rule of thumb. Print a test object and compare it with the model Measure it before printing parts that must fit; see Dimensional Accuracy. For lifting corners, see Warping and Brims, Rafts and Skirts.

Heat has a cost. Prusa warns that printing a lot of ABS or ASA in an enclosure can deform the printer's own plastic parts, such as the fan shroud and extruder parts, over time.

Bed adhesion

Prusa recommends smooth or powder-coated PEI with a glue stick for both. Glass may need a thin layer of ABS or ASA dissolved in acetone. Never put acetone or an ABS slurry on a powder-coated sheet; Prusa specifically warns against it. See Build Plates and Surfaces.

Emissions and ventilation

UltiMaker's US safety data sheet for its ABS says small quantities of styrene, present as a residual monomer, may be emitted during printing, and gives an observed emission rate of about 500 micrograms per hour in an UltiMaker S5 Maker spec. That is one maker's measurement for its own filament and printer, not a figure for ABS in general. California's Proposition 65 lists styrene as a substance known to the state to cause cancer, which the sheet quotes. The same sheet recommends general ventilation of at least 2 air changes per hour for one printer, assuming a 30 cubic meter room Maker spec, and process enclosures or local exhaust to keep airborne levels below exposure limits. Prusa adds that the ventilation must not blow across the print, or quality suffers.

• Print in a room you can ventilate, not a closed bedroom or office.
• The SDS names process enclosures and local exhaust ventilation as engineering controls. If you use an enclosure, follow its maker's guidance on filtration or exhaust.
• Use insulated gloves when handling the material hot, as the SDS advises; molten plastic causes thermal burns.
• Check the SDS for your exact spool. Formulations and their emissions differ by maker.

Storage and drying

Prusa calls ASA partially hygroscopic, and the Prusament drying table gives 80 °C for 4 hours for Prusament ASA Maker spec. Polymaker gives 70 °C for 6 hours for PolyLite ABS and 70 °C for 7 hours for Polymaker ASA Maker spec. UltiMaker's ABS SDS says to keep it out of direct sunlight; store spools sealed with desiccant as for any hygroscopic filament. See Drying and Storing Filament.

Post-processing

Both sand wet or dry and glue with acetone; ASA can also be welded with it. Both can be smoothed in acetone vapor for a glossy finish, which Prusa notes softens fine detail and sharp edges. Acetone has its own safety data sheet: read it and follow its ventilation and fire precautions. This guide gives no vapor-smoothing procedure.

Common failures

What you see	Usual cause	Where to go
Corners lift, part peels off	Cool air around the print, bed too cool	Warping
Cracks between layers partway up	Upper layers cool and shrink; drafts	Poor Layer Adhesion
Holes and fits too small	Shrinkage after cooling	Dimensional Accuracy
Printer fan shroud sagging	Long hot enclosure runs	Printer maker's guidance