3D Printing Info

Filament comparison

ASA-GF vs e-TPU

Compare printing settings, strength, heat resistance, dated prices and sources.

Glass-fibre ASA (ASA-GF) guideFoaming / expanded TPU (TPU Aero / TPU Air) guide

2 selected · all documented properties

Open these two in the interactive comparisonMore ASA-GF comparisonsMore e-TPU comparisons
ASA-GF vs e-TPU — documented properties and sources
PropertyGlass-fibre ASA (ASA-GF)ASAFoaming / expanded TPU (TPU Aero / TPU Air)FLEX
Market snapshot
Listing priceUSD/kg; dated snapshots$29.95/kg median; $26.99–$33.99/kg across 3 dated product listings$52.05/kg median; $41.99–$85.29/kg across 6 dated product listings
Identity & Market
Base polymer / chemistryASA reinforced with chopped glass fibre — 10 wt% (Spectrum ASA-X GF10), 15 wt% (ZYLtech ASA-GF)[1][2]Foaming thermoplastic polyurethane — a blowing agent expands the extrudate so the printed Shore hardness can be tuned by flow rate[3]
Densityg/cm³1.07 (ZYLtech) and 1.11 (Spectrum), ISO 1183[1][2]1.15 filament (Siraya Tech Flex TPU Air) and 1.05 (Roamr TPU Air HR), ISO 1183; the printed part falls to 0.51–0.93 depending on nozzle temperature (ISO 845)[4][5]
Typical priceUSD/kg1 kg spools cluster near 28[6][7]1 kg-equivalent spools span 42–85; the middle of the market is about 52[8][9][10][11][12][13]
Price range across brandsUSD/kg27–34 across brands; Ambrosia 27, ZYLtech 30, Siraya Tech 34[6][7][14]42–85 across brands; QIDI TPU-Aero 42, Siraya Tech Flex TPU Air 45, Phaetus aeFlex TPU-Aero 49 direct and 40 at West3D, Roamr TPU Air HR 80A 55 at 800 g, Recreus Filaflex Foamy 73 at 750 g, colorFabb varioShore 85 at 700 g[8][9][10][11][12][13][15]
Market availability1–5Niche, a handful of specialist brands[6][1][2]Available from several mainstream brands — colorFabb, Recreus, QIDI, Phaetus, Siraya Tech and FusRock all sell an active-foaming TPU[3][8][9][10][12][13]
Spool sizes & diameters1.75 and 2.85 mm; 1 kg spools[2][6]1.75 mm; 0.7, 0.75, 0.8, 1 and 3 kg spools[3][8][10][11][13]
Typical applicationsOutdoor brackets and mounts that need stiffness and dimensional stability under sun and moisture[1][2]Cushioning, midsoles, insoles and soft-touch parts where the softness needs to vary within one print; Siraya Tech's Roamr line is aimed specifically at printed footwear[3][11]
Diameter tolerance± mm±0.01 at 95 % probability and ±0.02 at 100 % (ZYLtech)[2]0.03 (Siraya Tech and Roamr, 1.75 mm)[4][5]
Printing Parameters
Nozzle temperature°C240–270 (Spectrum); 240–280 (ZYLtech)[1][2]230–270 (QIDI and Siraya Tech), 220–260 (Roamr); foaming activates near 230 °C and is strongest at the top of the range[3][4][5][12]
Bed temperature°C80–100 (Spectrum); 90–110 on PEI (ZYLtech)[1][2]30–45 (QIDI and Siraya Tech), 35–50 (Roamr) — a hot bed makes the foamed part over-stick[4][5][12]
Enclosure / chamber requirement1–5Enclosure recommended[16]Open frame is fine — Roamr states no enclosure is required[3][5]
Part cooling fan0–20 % (Spectrum)[1]100 % — cooling sets the foamed structure quickly (Siraya Tech and Roamr)[4][5]
Bed surface & adhesion aidPEI sheet, BuildTak or an adhesion aid such as Magigoo (Polymaker); Simplify3D also lists Kapton tape and ASA slurry[17][18]PEI sheet or painter's tape; Polymaker warns TPU can over-stick and advises a glue stick as a release agent, and Siraya Tech recommends PVP glue or Magigoo as a release agent on PEI[19][20][4]
Maximum volumetric flow (mm³/s; see test conditions)mm³/s2.4–5.6 at Spectrum's 30–70 mm/s on a 0.4 mm nozzle at 0.2 mm layer; ZYLtech allows up to 200 mm/s[1][2][21]Up to 12 (Siraya Tech, Flex TPU Air)[10]
Warping tendency1–5Moderate — needs adhesion aid or draught shield[16]Not documented
Bed-adhesion difficulty1–5Needs a specific surface plus adhesive[17]Not documented
Stringing / oozing tendency1–5Slight — Polymaker advises 1–2 mm retraction at 20–30 mm/s[17]Severe — the material expands inside the hot end, so it oozes on travel moves; QIDI states retraction tuning cannot fix it and Siraya Tech advises setting retraction distance and speed to zero[4][12]
Overall printing difficulty1–5Intermediate — dry filament and a tuned profile; ZYLtech requires a hardened nozzle of 0.6 mm or larger[2][1]Advanced — enclosure, hardware upgrades, tuning; both density and hardness follow nozzle temperature and flow[3]
Extruder requirementZYLtech specifies a hardened nozzle 0.6 mm or larger; Spectrum bases its settings on a 0.5 mm nozzle[2][1]Direct drive; the base material is a 92A TPU[3][22]
Hardware Wear & Reliability
Nozzle hardness required1–4Hardened steel required — Spectrum recommends ruby or hardened, ZYLtech requires hardened[1][2]Brass fine indefinitely — Roamr states plainly that no hardened nozzle is needed[23][5]
Abrasiveness1–5Highly abrasive — standard GF composite[1][2]Non-abrasive[23]
Nozzle clog risk1–5Moderate — needs dry filament and a clean nozzle; Prusa lists higher risk of nozzle clogging for glass-filled composites[24]Not documented
Heat-creep / jam sensitivity1–5Slightly sensitive[18]Not documented
Hotend requirementNo special hotend required[18]No special hot-end required, but a direct-drive extruder is (Simplify3D)[19]
Moisture Behaviour
Moisture absorption (hygroscopicity)1–5Moderate — the ASA matrix takes up 0.40–0.45 % saturated at 25 °C / 55 % RH; no glass-filled grade publishes its own figure[25][26][27]Moderate[28]
Equilibrium moisture content at ~50 % RH%Not documented1.09 water absorption (QIDI TPU-Aero; the standard is not stated)[12]
Drying temperature & timeNot documented70–80 °C for 4–6 h; keep below 15 % RH while printing (Siraya Tech, Roamr and QIDI)[4][5][12]
Symptoms when wetBubbling and popping at the nozzle, stringing and a rough surface[28]Bubbling and popping at the nozzle, stringing and a rough surface; Siraya Tech adds that moisture wrecks the foaming itself, not only the surface[28][4]
Effect of moisture on strengthNo dry-versus-conditioned figures are published; Polymaker groups the styrenics as moderate-sensitivity and absorbed water shows as bubbling and poor layer adhesion[28]Polymaker groups TPU with the highly hygroscopic materials; no dry-versus-conditioned figures are published[28]
Storage requirementSealed with desiccant; Polymaker rates the styrenics moderate-sensitivity[28]Sealed with desiccant; often kept in a dryer during the print[28]
Mechanical Properties
Tensile strength (XY)MPa33–36 at break, ISO 527 (ZYLtech; specimen type not stated); Spectrum quotes 55 at break on injection-moulded specimens[2][1]Falls with foaming: colorFabb 24 unfoamed and 12 foamed (ISO 527-1A); Siraya Tech 10.3 at break printed at 240 °C down to 3.8 at 270 °C; QIDI 6.81 at break (ISO 527, XY)[3][4][12]
Young's modulusMPa2540–2890 (ZYLtech; specimen type not stated) and 2550 (Spectrum, injection-moulded), ISO 527[2][1]50 unfoamed and 40 foamed (colorFabb, ISO 527-1A)[3]
Elongation at break%3.4 at break (ZYLtech; specimen type not stated); Spectrum quotes 2.80 at yield on injection-moulded specimens[2][1]465 unfoamed and 450 foamed (colorFabb, ISO 527-1A); Siraya Tech 629 at 240 °C down to 475 at 270 °C; Roamr 760 down to 540; QIDI 576 (ISO 527, XY)[3][4][5][12]
Flexural modulusMPa2130–2480 flexural modulus, ISO 178 (ZYLtech; specimen type not stated)[2]50 unfoamed and 40 foamed flexural modulus (colorFabb, ISO 178)[3]
Charpy impact, notchedkJ/m²8.3 notched Charpy at 23 °C on injection-moulded specimens (Spectrum, ISO 179-1eA); ZYLtech publishes notched Izod 6.9 by ISO 180 instead[1][2]Not documented
Other impact dataCharpy unnotched 25 kJ/m² at 23 °C on injection-moulded specimens (Spectrum, ISO 179-1eU); ZYLtech notched Izod 6.9 kJ/m² (ISO 180)[1][2]Not documented
Brittleness1–5Brittle — snaps with little warning; elongation at break 3.4 %[2]Very ductile — bends far before failing[3]
Hardness (scale-specific)Shore A / Shore D / RockwellNot documentedTunable by nozzle temperature: colorFabb 92 Shore A unfoamed; Siraya Tech 78 A printed at 240 °C falling to 63 A at 270 °C, Roamr TPU Air HR 80A 80 A down to 66 A and HR 85A 83 A down to 70 A (ISO 7619)[3][4][5][29]
Creep resistance / sustained load1–5Good — no creep test found; chopped glass fibre lifts modulus to 2540–2890 against 2379–2450 for unfilled ASA[2][26][25]Poor — no foamed-grade creep test; a printed 95A TPU bar crept from 74.5 to 82.7 mm over 5 days at 1.25 kg[30]
Fatigue / repeated-flex resistance1–5Below average — no GF-grade S-N curve; elongation at break falls to 3.4 % against 6.7–9.2 % for unfilled ASA[2][26][25]Excellent — living hinges viable[20]
Elasticity / flexibility1–5Rigid[2]Rubbery / highly elastic[3]
Thermal Properties
HDT at 0.45 MPa°C100 (Spectrum, injection-moulded, ISO 75 at 0.45 MPa)[1]Not documented
HDT at 1.8 MPa°C97–99 unannealed (ZYLtech, ISO 75 at 1.8 MPa; specimen type not stated); Spectrum 90 on injection-moulded specimens[2][1]Not documented
Melting point / Vicat°CAmorphous ASA matrix; Vicat 98 (Spectrum, ISO 306). ZYLtech quotes a 210–220 °C melting range by ISO 11357 for its grade[1][2]Vicat softening drops as the foam expands: 83 printed at 240 °C to 53 at 270 °C (Siraya Tech, ISO 306); QIDI 70.4[4][12]
Continuous service temperature°C93 — Prusa publishes this as the temperature resistance of Prusament ASA[31]Not documented
Annealing responseNot documentedFoaming activates near 230 °C and expands the extrudate about 1.6×; colorFabb advises dropping flow to 60–70 % to realise the weight saving, and Siraya Tech publishes a flow schedule from 85–90 % at 230 °C down to 50–55 % at 270 °C[3][4]
Flammability / UL 94Flammable; no UL 94 rating published[25]Not documented
Environment & Chemical
UV resistance1–5Excellent — designed for permanent outdoor use; Spectrum states the parts resist prolonged UV and moisture exposure[1][32]Good — years with some colour shift; Polymaker lists UV exposure among the conditions TPU withstands[20]
Chemical resistanceGood against weak acids, weak alkalis, oils and grease; dissolved by acetone[26]Withstands industrial solvents and UV exposure (Polymaker)[20]
Food contactNot food safe[17]Not food safe without specific certification (Polymaker)[20]
Biodegradability / compostabilityNot biodegradable[17]Not biodegradable[20]
RecyclabilityNot accepted in household plastic collection[17]Not accepted in household plastic collection[20]
Health & Safety
Fume toxicity1–5High — hazardous VOC such as styrene; enclosure and filtration needed[33][16]Low hazard — minimal VOC and particle emission; TPU was not among the nine filaments in the chamber study[33]
Hazardous species emittedStyrene. Bambu Lab states ABS and ASA release harmful gases such as styrene at printing temperature, which can be toxic and cause dizziness or nausea. Azimi et al. measured styrene from every styrenic filament tested but did not test ASA itself[16][33]Not documented
Ventilation / filtration requirement1–5Enclosure with carbon and HEPA filtration[33][16]Open a window / occasional ventilation[33]
Dust & fibre handling hazardGlass fibre is bound in the matrix; avoid inhaling sanding dust[1]Not documented
Post-Processing
Sanding & machiningSands well and takes filler before painting[17]Difficult to sand or smooth; Polymaker limits post-processing to trimming or tumbling[20]
Painting & finishingPaints readily; ASA holds colour outdoors so many parts are left unpainted[17]Not documented
Gluing & solvent weldingSolvent-welds with acetone[26]Cyanoacrylate bonds TPU; no common solvent welds it[20]
Vapour / chemical smoothingAcetone vapour smoothing works[26]No practical vapour smoothing[20]
Support material pairingHIPS breaks away or dissolves in d-limonene; Bambu Lab sells a Support for ABS that also serves ASA[16]Polymaker warns TPU supports are often very difficult to remove[20]
Dimensional accuracy & detailNot documentedFoamed surfaces are matte and textured; holding a consistent hardness means holding the nozzle temperature steady, and the printed density moves by nearly a factor of two across the 230–270 °C window[3][4]
Solvents & Solubility
Soluble inAcetone dissolves the resin and leaves the fibre; MEK, THF, ethyl acetate and chlorinated solvents attack the styrenic backbone.[34][26]DMF, DMSO, NMP and THF dissolve TPU; acetone, MEK and cyclohexanone are partial solvents. All laboratory reagents.[35]
Softened or crazed byLimonene attacks some grades — Prusa reports Prusament ASA Orange flaking apart as layer adhesion fails.[36]Toluene and benzene swell it up to +50 % by weight at 23 °C; the foamed wall soaks up esters and alcohols faster still.[35]
Solvent welding & smoothing agentAcetone vapour reaches only the resin fraction, so the fibre is left standing proud of the smoothed surface.[37][26]None practical — the true solvents (DMF, THF, NMP) are laboratory reagents and leave the joint swollen and weak.[35]

Material entries describe families or representative grades, not an interchangeable specification for every spool. Test methods, orientations and conditions may differ. Unknown values are marked “Not documented”. Prices and source dates remain historical snapshots; check the linked guide for product details. Differences highlight text, not a universal winner.

Sources for this comparison

  1. Spectrum ASA-X GF10 Technical Data Sheet (mechanical and thermal data marked injection-moulded) Spectrum Filaments · 2026-08 · tds
  2. ZYLtech ASA-GF Filament Technical Data Sheet v1 ZYLtech · 2026-08 · tds
  3. varioShore TPU Technical Data Sheet colorFabb · 2026-08 · tds
  4. Siraya Tech Flex TPU Air Technical Data Sheet Siraya Tech · 2026-08 · tds
  5. Roamr TPU Air HR 80A Technical Data Sheet Siraya Tech · 2026-08 · tds
  6. Filastruder product catalogue Filastruder · 2026-08 · vendor
  7. ZYLtech ASA-GF Glass Fiber filament — product page ZYLtech · 2026-08 · vendor
  8. Recreus product catalogue Recreus · 2026-08 · vendor
  9. varioShore TPU Natural — product page colorFabb US · 2026-08 · vendor
  10. Siraya Tech Flex TPU Air Black Filament — lightweight foaming flexible, product page Siraya Tech · 2026-08 · vendor
  11. Roamr TPU Air HR 80A Filament — product page Siraya Tech · 2026-08 · vendor
  12. TPU-Aero Lightweight TPU Filament — product page with specification tables QIDI Tech · 2026-08 · vendor
  13. aeFlex TPU-Aero — active foaming low weight TPU, product page Phaetus · 2026-08 · vendor
  14. Siraya Tech Fibreheart ASA-GF Filament product page Siraya Tech · 2026-08 · vendor
  15. Phaetus aeWorthy TPU-Aero — reseller listing West3D · 2026-08 · vendor
  16. ABS / ASA / PC Usage Guide Bambu Lab Wiki · 2026-08 · doc
  17. ASA — material basics Polymaker Wiki · 2026-08 · doc
  18. ASA — Ultimate 3D Printing Materials Guide Simplify3D · 2026-08 · doc
  19. Flexible (TPE/TPU) — Ultimate 3D Printing Materials Guide Simplify3D · 2026-08 · doc
  20. TPU — material basics Polymaker Wiki · 2026-08 · doc
  21. Max volumetric speed Prusa Knowledge Base · 2026-08 · doc
  22. NinjaFlex 85A Technical Specifications NinjaTek · 2026-08 · tds
  23. Extrudr Product Catalogue (DURAPRO PA12 data block) Extrudr · 2025-03 · tds
  24. Composite materials filled with carbon, kevlar or glass Prusa Knowledge Base · 2026-08 · doc
  25. Bambu Filament Technical Data Sheet V3.0 — ASA Bambu Lab · 2026-08 · tds
  26. PolyLite ASA Technical Data Sheet Polymaker · 2024-11 · tds
  27. Prusament ASA Technical Datasheet v1.1 Prusa Polymers · 2024-05 · tds
  28. Wet Filament — signs, causes and drying Polymaker Wiki · 2026-08 · doc
  29. Roamr TPU Air HR 85A Technical Data Sheet Siraya Tech · 2026-08 · tds
  30. BambuLab TPU 95A HF vs Qidi TPU 95A HF — results spreadsheet My Tech Fun (Igor Gaspar) · 2024-02 · test
  31. Prusament ASA — material page Prusa Polymers · 2026-08 · doc
  32. ASA — FDM Material Data Sheet (includes 1000 h QUV exposure results) Stratasys · 2026-08 · tds
  33. Emissions of Ultrafine Particles and Volatile Organic Compounds from Commercially Available Desktop Three-Dimensional Printers with Multiple Filaments (Azimi et al.) Environmental Science & Technology 50(3) 1260-1268 · 2016-01 · paper
  34. Chemical resistance — resistance of Ensinger plastics to chemicals (DIN 50 014, 23/50) Ensinger · 2026-08 · tds
  35. Elastollan — Chemical properties: swelling and chemical resistance BASF · 2026-08 · tds
  36. HIPS — Knowledge Base Prusa Research · 2026-08 · doc
  37. Improve your 3D prints with chemical smoothing Prusa Research · 2026-08 · doc