3D Printing Info

Filament comparison

e-TPU vs PLA Metal

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

Foaming / expanded TPU (TPU Aero / TPU Air) guideMetal-filled PLA guide

2 selected · all documented properties

Open these two in the interactive comparisonMore e-TPU comparisonsMore PLA Metal comparisons
e-TPU vs PLA Metal — documented properties and sources
PropertyFoaming / expanded TPU (TPU Aero / TPU Air)FLEXMetal-filled PLAPLA
Market snapshot
Listing priceUSD/kg; dated snapshots$52.05/kg median; $41.99–$85.29/kg across 6 dated product listings$79.69/kg median; $24.99–$94.99/kg across 6 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]PLA loaded with real metal powder — bronze, copper, steel or iron. Bambu Lab's PLA Sparkle TDS states it has "metal particles included in its composition"; its separately sold PLA Metal does not, and the store page says so explicitly[2][3][4][5][6][7]
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)[8][9]1.26 (Bambu Lab Sparkle, a trace-metal glitter grade) up to 3.9–4.0 for colorFabb bronze and copper and 2.3 for Proto-pasta steel, ISO 1183[5][2][3][10]
Typical priceUSD/kg1 kg-equivalent spools span 42–85; the middle of the market is about 52[11][12][13][14][15][16]1 kg spools cluster near 78[17][18][4]
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[11][12][13][14][15][16][19]25–95 across brands; Bambu Lab Sparkle 25, Proto-pasta iron 65, colorFabb bronze and copper 84, Proto-pasta steel 95[17][4][18][10]
Market availability1–5Available from several mainstream brands — colorFabb, Recreus, QIDI, Phaetus, Siraya Tech and FusRock all sell an active-foaming TPU[1][11][12][13][15][16]Available from several mainstream brands[18][4][10][17]
Spool sizes & diameters1.75 mm; 0.7, 0.75, 0.8, 1 and 3 kg spools[1][11][13][14][16]1.75 and 2.85 mm; 0.1, 0.5, 0.75, 1 and 1.5 kg spools[20][18]
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][14]Decorative castings and props that are polished or left to patinate; the density gives prints a metallic heft[2][4]
Diameter tolerance± mm0.03 (Siraya Tech and Roamr, 1.75 mm)[8][9]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][8][9][15]195–220 (colorFabb bronze and copper); 192 (Proto-pasta iron); 198 (Proto-pasta steel); 190–230 (Bambu Lab Sparkle)[2][4][10][5]
Bed temperature°C30–45 (QIDI and Siraya Tech), 35–50 (Roamr) — a hot bed makes the foamed part over-stick[8][9][15]50–60 (colorFabb, Proto-pasta); 35–45 (Bambu Lab)[2][4][5]
Enclosure / chamber requirement1–5Open frame is fine — Roamr states no enclosure is required[1][9]Open frame is fine[2]
Part cooling fan100 % — cooling sets the foamed structure quickly (Siraya Tech and Roamr)[8][9]On (colorFabb copper); 0–100 % (colorFabb bronze)[2][3]
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[21][22][8]Glass plate with glue stick or tape (colorFabb)[2][3]
Maximum volumetric flow (mm³/s; see test conditions)mm³/sUp to 12 (Siraya Tech, Flex TPU Air)[13]1.6–2.4 at Proto-pasta's 20–30 mm/s for iron and steel, 3.2–8 at colorFabb's 40–100 mm/s, on a 0.4 mm nozzle at 0.2 mm layer[4][10][2][23]
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[8][15]Not documented
Overall printing difficulty1–5Advanced — enclosure, hardware upgrades, tuning; both density and hardness follow nozzle temperature and flow[1]Intermediate — dry filament and a tuned profile; brittle in filament form and slow to print[4][10]
Extruder requirementDirect drive; the base material is a 92A TPU[1][24]Proto-pasta advises an extrusion width 0.05 mm larger than the nozzle and warns that feeding is inconsistent below 0.4 mm and on Bowden machines[4][10]
Hardware Wear & Reliability
Nozzle hardness required1–4Brass fine indefinitely — Roamr states plainly that no hardened nozzle is needed[25][9]Brass acceptable; hardened steel for volume work[4][10]
Abrasiveness1–5Non-abrasive[25]Moderately abrasive — metal fill[4][10]
Nozzle clog risk1–5Not documentedModerate — needs dry filament and a clean nozzle[10]
Hotend requirementNo special hot-end required, but a direct-drive extruder is (Simplify3D)[21]Proto-pasta recommends a wear-resistant or larger nozzle for longer service intervals[4][10]
Other hardware wearNot documentedProto-pasta warns of more frequent nozzle replacement and first-layer adjustment[4][10]
Moisture Behaviour
Moisture absorption (hygroscopicity)1–5Moderate[26]Moderate — the PLA matrix takes up 0.40–0.51 % saturated; the metal powder itself does not absorb water[27][28]
Equilibrium moisture content at ~50 % RH%1.09 water absorption (QIDI TPU-Aero; the standard is not stated)[15]Not documented
Drying temperature & time70–80 °C for 4–6 h; keep below 15 % RH while printing (Siraya Tech, Roamr and QIDI)[8][9][15]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[26][8]Not documented
Effect of moisture on strengthPolymaker groups TPU with the highly hygroscopic materials; no dry-versus-conditioned figures are published[26]Polymaker rates PLA low-sensitivity and publishes no dry-versus-conditioned figures for this grade; absorbed water flashes to steam and shows as bubbling and poor layer adhesion[26]
Storage requirementSealed with desiccant; often kept in a dryer during the print[26]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][8][15]25 (colorFabb copper) and 30 (colorFabb bronze), ISO 527-1A; Bambu Lab Sparkle 39 ± 3 printed XY, ISO 527[2][3][5]
Young's modulusMPa50 unfoamed and 40 foamed (colorFabb, ISO 527-1A)[1]1940 ± 230 printed XY, ISO 527 (Bambu Lab Sparkle)[5]
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][8][9][15]3–10 (colorFabb copper) and 5–10 (colorFabb bronze), ISO 527-1A; 11.7 for Bambu Lab Sparkle printed XY[2][3][5]
Flexural strengthMPaNot documented75 ± 4 printed XY, ISO 178 (Bambu Lab Sparkle)[5]
Flexural modulusMPa50 unfoamed and 40 foamed flexural modulus (colorFabb, ISO 178)[1]2350 ± 140 printed XY, ISO 178 (Bambu Lab Sparkle)[5]
Charpy impact, notchedkJ/m²Not documented23.2 ± 2.4 printed XY, ISO 179, notched (Bambu Lab Sparkle)[5]
Other impact dataNot documentedIzod notched 4.5 kJ/m² for colorFabb bronzeFill and 10 kJ/m² for copperFill (ISO 180); Charpy unnotched 66.5 kJ/m² for Bambu Lab Sparkle[2][3][5]
Layer adhesion / Z tensileMPaNot documented32 ± 2 printed Z, ISO 527 (Bambu Lab Sparkle)[5]
Brittleness1–5Very ductile — bends far before failing[1]Brittle — Proto-pasta describes both its iron and steel grades as more brittle than standard PLA in filament form[4][10]
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][8][9][29]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[30]Poor — no metal-filled creep test; plain printed PLA sagged from 12 to 16.2–21.8 mm over 5 days at 1.25 kg[31][32][33]
Fatigue / repeated-flex resistance1–5Excellent — living hinges viable[22]Poor — no grade-specific S-N curve; plain printed PLA ran 38 000–49 000 cycles at 30 % of tensile strength and Proto-pasta describes its iron and steel grades as more brittle than standard PLA[34][4][10]
Elasticity / flexibility1–5Rubbery / highly elastic[1]Rigid[5]
Z strength as % of XY%Not documented82 by tensile (printed, Bambu Lab Sparkle)[5]
Thermal Properties
HDT at 0.45 MPa°CNot documented55 (ISO 75, 0.45 MPa, Bambu Lab Sparkle)[5]
HDT at 1.8 MPa°CNot documented53 (ISO 75, 1.8 MPa, Bambu Lab Sparkle)[5]
Glass transition (Tg)°CNot documented56 (DSC, Bambu Lab Sparkle)[5]
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[8][15]156 peak melt (DSC, Bambu Lab Sparkle)[5]
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][8]Not documented
Environment & Chemical
UV resistance1–5Good — years with some colour shift; Polymaker lists UV exposure among the conditions TPU withstands[22]Degrades within weeks outdoors[35]
Outdoor durabilityNot documentedProto-pasta markets its iron grade as rustable — the iron oxidises deliberately when exposed to moisture[4]
Chemical resistanceWithstands industrial solvents and UV exposure (Polymaker)[22]Not documented
Food contactNot food safe without specific certification (Polymaker)[22]Not documented
Biodegradability / compostabilityNot biodegradable[22]Not documented
RecyclabilityNot accepted in household plastic collection[22]Not documented
Electrical & ESD propertiesNot documentedProto-pasta magnetic iron PLA is ferromagnetic and responds to magnets[4]
Health & Safety
Fume toxicity1–5Low hazard — minimal VOC and particle emission; TPU was not among the nine filaments in the chamber study[36]Low hazard — minimal VOC and particle emission[36]
Ventilation / filtration requirement1–5Open a window / occasional ventilation[36]None needed in a normal room[36]
Post-Processing
Sanding & machiningDifficult to sand or smooth; Polymaker limits post-processing to trimming or tumbling[22]Polishing is the intended finish — colorFabb and Proto-pasta both sell these grades to be sanded and buffed to a metallic shine[2][3][10]
Gluing & solvent weldingCyanoacrylate bonds TPU; no common solvent welds it[22]Not documented
Vapour / chemical smoothingNo practical vapour smoothing[22]Not documented
Support material pairingPolymaker warns TPU supports are often very difficult to remove[22]Not documented
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][8]colorFabb notes the metal fill increases die swell, so flow needs raising above plain PLA[3]
Solvents & Solubility
Soluble inDMF, DMSO, NMP and THF dissolve TPU; acetone, MEK and cyclohexanone are partial solvents. All laboratory reagents.[37]Chloroform dissolves the PLA matrix (10 % w/v, 2–4 h at 23 °C) and leaves the filler as loose sludge; laboratory reagent.[38]
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.[37]Acetone, ethyl acetate and toluene plasticise the matrix but dissolve <1 % even at 65 °C; acetone submersion crazes parts.[38][39]
Solvent welding & smoothing agentNone practical — the true solvents (DMF, THF, NMP) are laboratory reagents and leave the joint swollen and weak.[37]Chloroform vapour attacks only the resin fraction, so the filler is left standing proud; no workshop-safe agent exists.[40][39]

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. bronzeFill technical data sheet colorFabb · 2026-08 · tds
  3. copperFill technical data sheet colorFabb · 2026-08 · tds
  4. Magnetic Iron PLA — product page and technical data Proto-pasta · 2026-08 · tds
  5. Bambu Filament Technical Data Sheet — PLA Sparkle Bambu Lab · 2026-08 · tds
  6. PLA Metal — product page Bambu Lab US Store · 2026-08 · vendor
  7. Bambu Filament Technical Data Sheet V3.0 — PLA Metal Bambu Lab · 2026-08 · tds
  8. Siraya Tech Flex TPU Air Technical Data Sheet Siraya Tech · 2026-08 · tds
  9. Roamr TPU Air HR 80A Technical Data Sheet Siraya Tech · 2026-08 · tds
  10. Stainless Steel PLA — product page and technical data Proto-pasta · 2026-08 · tds
  11. Recreus product catalogue Recreus · 2026-08 · vendor
  12. varioShore TPU Natural — product page colorFabb US · 2026-08 · vendor
  13. Siraya Tech Flex TPU Air Black Filament — lightweight foaming flexible, product page Siraya Tech · 2026-08 · vendor
  14. Roamr TPU Air HR 80A Filament — product page Siraya Tech · 2026-08 · vendor
  15. TPU-Aero Lightweight TPU Filament — product page with specification tables QIDI Tech · 2026-08 · vendor
  16. aeFlex TPU-Aero — active foaming low weight TPU, product page Phaetus · 2026-08 · vendor
  17. PLA Sparkle — product page Bambu Lab US Store · 2026-08 · vendor
  18. bronzeFill — product page colorFabb US · 2026-08 · vendor
  19. Phaetus aeWorthy TPU-Aero — reseller listing West3D · 2026-08 · vendor
  20. Proto-pasta product catalogue Proto-pasta · 2026-08 · vendor
  21. Flexible (TPE/TPU) — Ultimate 3D Printing Materials Guide Simplify3D · 2026-08 · doc
  22. TPU — material basics Polymaker Wiki · 2026-08 · doc
  23. Max volumetric speed Prusa Knowledge Base · 2026-08 · doc
  24. NinjaFlex 85A Technical Specifications NinjaTek · 2026-08 · tds
  25. Extrudr Product Catalogue (DURAPRO PA12 data block) Extrudr · 2025-03 · tds
  26. Wet Filament — signs, causes and drying Polymaker Wiki · 2026-08 · doc
  27. Bambu Filament Technical Data Sheet V3.0 — PLA Basic Bambu Lab · 2026-08 · tds
  28. PolyLite PLA Technical Data Sheet V5.4 Polymaker · 2024-11 · tds
  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. BambuLab PLA Basic vs PLA Tough vs PLA-CF — results spreadsheet My Tech Fun (Igor Gaspar) · 2026-08 · test
  32. Polymaker PLA Pro vs PLA-CF — results spreadsheet My Tech Fun (Igor Gaspar) · 2026-08 · test
  33. Carbon Fiber PLA vs META-PLA vs PLA+ vs PLA by Sunlu — results spreadsheet My Tech Fun (Igor Gaspar) · 2026-08 · test
  34. Mechanical Properties of Additively Manufactured Polymeric Materials — PLA and PETG — For Biomechanical Applications Polymers 16(13):1868 · 2024-06 · paper
  35. PLA — material guide Prusa Knowledge Base · 2026-08 · doc
  36. 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
  37. Elastollan — Chemical properties: swelling and chemical resistance BASF · 2026-08 · tds
  38. Solubility Study of Ingeo Biopolymer Grades in Common Organic Solvents (NWPD003) NatureWorks · 2019-10 · tds
  39. Improve your 3D prints with chemical smoothing Prusa Research · 2026-08 · doc
  40. Effect of vapour smoothing in trichloromethane on 3D printed PLA — surface, mechanical and chemical structure Pitale, Keche & Chopra, Engineering Research Express 6(4) 045579 · 2024-12 · paper