3D Printing Info

Filament comparison

e-TPU vs HT soluble

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

Foaming / expanded TPU (TPU Aero / TPU Air) guideHigh-temperature support guide

2 selected · all documented properties

Open these two in the interactive comparisonMore e-TPU comparisonsMore HT soluble comparisons
e-TPU vs HT soluble — documented properties and sources
PropertyFoaming / expanded TPU (TPU Aero / TPU Air)FLEXHigh-temperature supportSUPPORT
Market snapshot
Listing priceUSD/kg; dated snapshots$52.05/kg median; $41.99–$85.29/kg across 6 dated product listings$209.00/kg median; $100.00–$290.00/kg across 4 dated product listings
Identity & Market
Base polymer / chemistryFoaming thermoplastic polyurethane — a blowing agent expands the extrudate so the printed Shore hardness can be tuned by flow rate[1]Break-away support compounded to survive high-temperature print chambers; 3DXTech sells separate grades for PC/ABS and for the PAEK and PEI class[2][3]
Densityg/cm³1.15 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]1.37 (3DXTech THERMAX HTS1, ISO 1183)[2]
Typical priceUSD/kg1 kg-equivalent spools span 42–85; the middle of the market is about 52[6][7][8][9][10][11]1 kg-equivalent spools cluster near 168[12]
Price range across brandsUSD/kg42–85 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[6][7][8][9][10][11][13]100–290 across grades; 3DXTech THERMAX MTS1 100 at 2 kg, HTS2 168 at 250 g, HTS1 250 at 500 g, IEMAI 3D HT-SP 290 at 1 kg[12][14]
Market availability1–5Available from several mainstream brands — colorFabb, Recreus, QIDI, Phaetus, Siraya Tech and FusRock all sell an active-foaming TPU[1][6][7][8][10][11]Niche, a handful of specialist brands[12][14]
Spool sizes & diameters1.75 mm; 0.7, 0.75, 0.8, 1 and 3 kg spools[1][6][8][9][11]1.75 mm; 250 g, 500 g, 1 kg and 2 kg spools[12]
Typical applicationsCushioning, 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[1][9]Support for PEEK, PEI and PC-class prints, where PVA and PLA-based supports would decompose[2][3]
Diameter tolerance± mm0.03 (Siraya Tech and Roamr, 1.75 mm)[4][5]Not documented
Printing Parameters
Nozzle temperature°C230–270 (QIDI and Siraya Tech), 220–260 (Roamr); foaming activates near 230 °C and is strongest at the top of the range[1][4][5][10]Not documented
Bed temperature°C30–45 (QIDI and Siraya Tech), 35–50 (Roamr) — a hot bed makes the foamed part over-stick[4][5][10]Not documented
Enclosure / chamber requirement1–5Open frame is fine — Roamr states no enclosure is required[1][5]Actively heated chamber required — it is used inside high-temperature builds[2]
Part cooling fan100 % — cooling sets the foamed structure quickly (Siraya Tech and Roamr)[4][5]Not documented
Bed surface & adhesion aidPEI 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[15][16][4]Not documented
Maximum volumetric flow (mm³/s; see test conditions)mm³/sUp to 12 (Siraya Tech, Flex TPU Air)[8]Not documented
Stringing / oozing tendency1–5Severe — 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][10]Not documented
Overall printing difficulty1–5Advanced — enclosure, hardware upgrades, tuning; both density and hardness follow nozzle temperature and flow[1]Expert / industrial hardware only[2]
Extruder requirementDirect drive; the base material is a 92A TPU[1][17]A dual-extruder machine rated for high-temperature materials; 3DXTech states the grade is intended for dual-extruder printers designed to print high-temp materials[18]
Hardware Wear & Reliability
Nozzle hardness required1–4Brass fine indefinitely — Roamr states plainly that no hardened nozzle is needed[19][5]Brass fine indefinitely[2]
Abrasiveness1–5Non-abrasive[19]Non-abrasive[2]
Nozzle clog risk1–5Not documentedModerate — needs dry filament and a clean nozzle; 3DXTech lists no special nozzle concerns but a mandatory 120 °C pre-dry for HTS1 and 80 °C for MTS1[18][20]
Hotend requirementNo special hot-end required, but a direct-drive extruder is (Simplify3D)[15]Not documented
Moisture Behaviour
Moisture absorption (hygroscopicity)1–5Moderate[21]Not documented
Equilibrium moisture content at ~50 % RH%1.09 water absorption (QIDI TPU-Aero; the standard is not stated)[10]Not documented
Drying temperature & time70–80 °C for 4–6 h; keep below 15 % RH while printing (Siraya Tech, Roamr and QIDI)[4][5][10]Not documented
Symptoms when wetBubbling and popping at the nozzle, stringing and a rough surface; Siraya Tech adds that moisture wrecks the foaming itself, not only the surface[21][4]Not documented
Effect of moisture on strengthPolymaker groups TPU with the highly hygroscopic materials; no dry-versus-conditioned figures are published[21]No dry-versus-conditioned figures are published; 3DXTech mandates a 120 °C, 4 h pre-dry for HTS1 and 80 °C for MTS1 because trapped water flashes to steam at these nozzle temperatures[18][20]
Storage requirementSealed with desiccant; often kept in a dryer during the print[21]Not documented
Mechanical Properties
Tensile strength (XY)MPaFalls 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)[1][4][10]Not documented
Young's modulusMPa50 unfoamed and 40 foamed (colorFabb, ISO 527-1A)[1]Not documented
Elongation at break%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)[1][4][5][10]Not documented
Flexural modulusMPa50 unfoamed and 40 foamed flexural modulus (colorFabb, ISO 178)[1]Not documented
Brittleness1–5Very ductile — bends far before failing[1]Not documented
Hardness (scale-specific)Shore A / Shore D / RockwellTunable 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)[1][4][5][22]Not documented
Creep resistance / sustained load1–5Poor — 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[23]Not documented
Fatigue / repeated-flex resistance1–5Excellent — living hinges viable[16]Not documented
Elasticity / flexibility1–5Rubbery / highly elastic[1]Not documented
Wear resistance & frictionNot documented3DXTech marks tensile strength, modulus and elongation as not applicable for its support grades — they are not characterised as structural materials[2]
Thermal Properties
HDT at 1.8 MPa°CNot documented205 (THERMAX HTS1, printed XY, ISO 75 at 1.8 MPa)[2]
Glass transition (Tg)°CNot documented225 (3DXTech THERMAX HTS1, DSC) — high enough to stay solid inside a PEI or PEEK build[2]
Melting point / Vicat°CVicat softening drops as the foam expands: 83 printed at 240 °C to 53 at 270 °C (Siraya Tech, ISO 306); QIDI 70.4[4][10]Not documented
Annealing responseFoaming 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[1][4]Not documented
Environment & Chemical
UV resistance1–5Good — years with some colour shift; Polymaker lists UV exposure among the conditions TPU withstands[16]Not documented
Chemical resistanceWithstands industrial solvents and UV exposure (Polymaker)[16]Not documented
Food contactNot food safe without specific certification (Polymaker)[16]Not documented
Biodegradability / compostabilityNot biodegradable[16]Not documented
RecyclabilityNot accepted in household plastic collection[16]Not documented
Electrical & ESD propertiesNot documentedSurface resistance above 10^13 ohm/sq on all three THERMAX support grades (ASTM D257) — insulating[2][24][3]
Health & Safety
Fume toxicity1–5Low hazard — minimal VOC and particle emission; TPU was not among the nine filaments in the chamber study[25]Low hazard — minimal VOC and particle emission; none of these materials was in the chamber study[25]
Ventilation / filtration requirement1–5Open a window / occasional ventilation[25]Open a window / occasional ventilation[25]
Post-Processing
Sanding & machiningDifficult to sand or smooth; Polymaker limits post-processing to trimming or tumbling[16]Not documented
Gluing & solvent weldingCyanoacrylate bonds TPU; no common solvent welds it[16]Not documented
Vapour / chemical smoothingNo practical vapour smoothing[16]Not documented
Support material pairingPolymaker warns TPU supports are often very difficult to remove[16]This is the support material. MTS1 is matched to PC/ABS and PC; HTS1 and HTS2 to the higher-temperature classes[3][2]
Dimensional accuracy & detailFoamed 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[1][4]Not documented
Solvents & Solubility
Soluble inDMF, DMSO, NMP and THF dissolve TPU; acetone, MEK and cyclohexanone are partial solvents. All laboratory reagents.[26]Aqueous alkali, not water: IEMAI specifies an alkaline bath in an ultrasonic cleaner until the support dissolves.[14]
Softened or crazed byToluene and benzene swell it up to +50 % by weight at 23 °C; the foamed wall soaks up esters and alcohols faster still.[26]Not documented
Solvent welding & smoothing agentNone practical — the true solvents (DMF, THF, NMP) are laboratory reagents and leave the joint swollen and weak.[26]None — the alkaline bath dissolves the support rather than welding anything.[14]

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. varioShore TPU Technical Data Sheet colorFabb · 2026-08 · tds
  2. THERMAX HTS1 Break Away Support Technical Data Sheet v1.0 3DXTech · 2026-08 · tds
  3. THERMAX MTS1 Break Away Support Technical Data Sheet v1.0 3DXTech · 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. Recreus product catalogue Recreus · 2026-08 · vendor
  7. varioShore TPU Natural — product page colorFabb US · 2026-08 · vendor
  8. Siraya Tech Flex TPU Air Black Filament — lightweight foaming flexible, product page Siraya Tech · 2026-08 · vendor
  9. Roamr TPU Air HR 80A Filament — product page Siraya Tech · 2026-08 · vendor
  10. TPU-Aero Lightweight TPU Filament — product page with specification tables QIDI Tech · 2026-08 · vendor
  11. aeFlex TPU-Aero — active foaming low weight TPU, product page Phaetus · 2026-08 · vendor
  12. 3DXTech product catalogue 3DXTech · 2026-08 · vendor
  13. Phaetus aeWorthy TPU-Aero — reseller listing West3D · 2026-08 · vendor
  14. IEMAI 3D HT-SP alkaline-soluble support filament — store page IEMAI 3D · 2026-08 · vendor
  15. Flexible (TPE/TPU) — Ultimate 3D Printing Materials Guide Simplify3D · 2026-08 · doc
  16. TPU — material basics Polymaker Wiki · 2026-08 · doc
  17. NinjaFlex 85A Technical Specifications NinjaTek · 2026-08 · tds
  18. THERMAX HTS1 — product page 3DXTech · 2026-08 · vendor
  19. Extrudr Product Catalogue (DURAPRO PA12 data block) Extrudr · 2025-03 · tds
  20. THERMAX MTS1 — product page 3DXTech · 2026-08 · vendor
  21. Wet Filament — signs, causes and drying Polymaker Wiki · 2026-08 · doc
  22. Roamr TPU Air HR 85A Technical Data Sheet Siraya Tech · 2026-08 · tds
  23. BambuLab TPU 95A HF vs Qidi TPU 95A HF — results spreadsheet My Tech Fun (Igor Gaspar) · 2024-02 · test
  24. THERMAX HTS2 Break Away Support Technical Data Sheet v1.0 3DXTech · 2026-08 · tds
  25. 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
  26. Elastollan — Chemical properties: swelling and chemical resistance BASF · 2026-08 · tds