TPU with a blowing agent, sold as varioShore, Filaflex Foamy, TPU-Aero and TPU Air: foaming starts near 230 °C and the printed part drops from about 0.9 to 0.5 g/cm³ and from 80 to 63 Shore…
Open in interactive comparisonCushioning, 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
TPU with a blowing agent, sold as varioShore, Filaflex Foamy, TPU-Aero and TPU Air: foaming starts near 230 °C and the printed part drops from about 0.9 to 0.5 g/cm³ and from 80 to 63 Shore A as the nozzle climbs to 270 °C, so density and hardness are set by temperature and flow rather than by the spool.
Foaming TPU is chosen when an elastomer part should be lighter or softer than a solid print of the same outline. Expansion creates a cellular structure, so nozzle temperature and extrusion flow affect density and firmness as well as dimensions. Manufacturers use this for cushioning and compliant surfaces: colorFabb lists RC tyres, grips and transport-case inserts, while Siraya Tech develops its Roamr foaming grades specifically for printed footwear.
Foaming TPU is not interchangeable with a solid 85A or 95A TPU, and different foaming formulations do not have the same rebound. Siraya distinguishes its footwear-tuned Roamr from ordinary TPU Air. The practical limit is process consistency: changing temperature or flow changes expansion, wall thickness and feel. Compression, recovery and durability must be evaluated at the intended deformation; softness alone cannot predict repeated-load performance.
FDM · Siraya Tech Roamr TPU Air HR 80A and 85A foaming formulations · Manufacturer-listed applications
Siraya Tech shows printed shoes and slides and positions Roamr TPU Air HR specifically for footwear. Its high-rebound formulations are distinct from ordinary TPU Air; this application should not be attributed to every foaming TPU.
FDM · colorFabb varioShore TPU, actively foaming TPU · Manufacturer-listed applications
colorFabb identifies flexible RC tyres and reusable cushioning inserts as applications for varioShore. Controlled expansion offers lower weight and adjustable softness, while the geometry still determines how the part carries load.
Check the model’s material and process notes before choosing a filament.
Representative catalog values. Check the exact grade and its linked conditions before using a setting.
230–270 (QIDI and Siraya Tech), 220–260 (Roamr); foaming activates near 230 °C and is strongest at…
230–270 (QIDI and Siraya Tech), 220–260 (Roamr); foaming activates near 230 °C and is strongest at the top of the range
30–45 (QIDI and Siraya Tech), 35–50 (Roamr)
30–45 (QIDI and Siraya Tech), 35–50 (Roamr) — a hot bed makes the foamed part over-stick
Open frame is fine
Open frame is fine — Roamr states no enclosure is required
70–80 °C for 4–6 h; keep below 15 % RH while printing (Siraya Tech, Roamr and QIDI)
70–80 °C for 4–6 h; keep below 15 % RH while printing (Siraya Tech, Roamr and QIDI)
Open a topic to explore the complete data. Each value keeps its original conditions, units and dated sources.
| Property and unit | Published value and conditions | Sources and dates |
|---|---|---|
| Base polymer / chemistry | Foaming thermoplastic polyurethane — a blowing agent expands the extrudate so the printed Shore hardness can be tuned by flow rate | 1 source
|
| Density (g/cm³) | 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) | 2 sources
|
| Typical price (USD/kg) | 1 kg-equivalent spools span 42–85; the middle of the market is about 52 | 6 sources
|
| Price range across brands (USD/kg) | 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 | 7 sources
|
| Market availability (1–5) | Available from several mainstream brands — colorFabb, Recreus, QIDI, Phaetus, Siraya Tech and FusRock all sell an active-foaming TPU | 6 sources
|
| Spool sizes & diameters | 1.75 mm; 0.7, 0.75, 0.8, 1 and 3 kg spools | 5 sources
|
| Typical applications | 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 | 2 sources
|
| Diameter tolerance (± mm) | 0.03 (Siraya Tech and Roamr, 1.75 mm) | 2 sources
|
| Property and unit | Published value and conditions | Sources and dates |
|---|---|---|
| Nozzle temperature (°C) | 230–270 (QIDI and Siraya Tech), 220–260 (Roamr); foaming activates near 230 °C and is strongest at the top of the range | 4 sources
|
| Bed temperature (°C) | 30–45 (QIDI and Siraya Tech), 35–50 (Roamr) — a hot bed makes the foamed part over-stick | 3 sources
|
| Enclosure / chamber requirement (1–5) | Open frame is fine — Roamr states no enclosure is required | 2 sources
|
| Part cooling fan | 100 % — cooling sets the foamed structure quickly (Siraya Tech and Roamr) | 2 sources
|
| Bed surface & adhesion aid | 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 | 3 sources
|
| Maximum volumetric flow (mm³/s; see test conditions) (mm³/s) | Up to 12 (Siraya Tech, Flex TPU Air) | 1 source |
| Stringing / oozing tendency (1–5) | 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 | 2 sources
|
| Overall printing difficulty (1–5) | Advanced — enclosure, hardware upgrades, tuning; both density and hardness follow nozzle temperature and flow | 1 source
|
| Extruder requirement | Direct drive; the base material is a 92A TPU | 2 sources
|
| Property and unit | Published value and conditions | Sources and dates |
|---|---|---|
| Nozzle hardness required (1–4) | Brass fine indefinitely — Roamr states plainly that no hardened nozzle is needed | 2 sources
|
| Abrasiveness (1–5) | Non-abrasive | 1 source
|
| Hotend requirement | No special hot-end required, but a direct-drive extruder is (Simplify3D) | 1 source
|
| Property and unit | Published value and conditions | Sources and dates |
|---|---|---|
| Moisture absorption (hygroscopicity) (1–5) | Moderate | 1 source
|
| Equilibrium moisture content at ~50 % RH (%) | 1.09 water absorption (QIDI TPU-Aero; the standard is not stated) | 1 source
|
| Drying temperature & time | 70–80 °C for 4–6 h; keep below 15 % RH while printing (Siraya Tech, Roamr and QIDI) | 3 sources
|
| Symptoms when wet | Bubbling and popping at the nozzle, stringing and a rough surface; Siraya Tech adds that moisture wrecks the foaming itself, not only the surface | 2 sources
|
| Effect of moisture on strength | Polymaker groups TPU with the highly hygroscopic materials; no dry-versus-conditioned figures are published | 1 source
|
| Storage requirement | Sealed with desiccant; often kept in a dryer during the print | 1 source
|
| Property and unit | Published value and conditions | Sources and dates |
|---|---|---|
| Tensile strength (XY) (MPa) | 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 sources
|
| Young's modulus (MPa) | 50 unfoamed and 40 foamed (colorFabb, ISO 527-1A) | 1 source
|
| 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) | 4 sources
|
| Flexural modulus (MPa) | 50 unfoamed and 40 foamed flexural modulus (colorFabb, ISO 178) | 1 source
|
| Brittleness (1–5) | Very ductile — bends far before failing | 1 source
|
| Hardness (scale-specific) (Shore A / Shore D / Rockwell) | Tunable 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) | 4 sources
|
| Creep resistance / sustained load (1–5) | 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 | 1 source
|
| Fatigue / repeated-flex resistance (1–5) | Excellent — living hinges viable | 1 source
|
| Elasticity / flexibility (1–5) | Rubbery / highly elastic | 1 source
|
| Property and unit | Published value and conditions | Sources and dates |
|---|---|---|
| Melting point / Vicat (°C) | Vicat softening drops as the foam expands: 83 printed at 240 °C to 53 at 270 °C (Siraya Tech, ISO 306); QIDI 70.4 | 2 sources
|
| Annealing response | Foaming 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 | 2 sources
|
| Property and unit | Published value and conditions | Sources and dates |
|---|---|---|
| UV resistance (1–5) | Good — years with some colour shift; Polymaker lists UV exposure among the conditions TPU withstands | 1 source
|
| Chemical resistance | Withstands industrial solvents and UV exposure (Polymaker) | 1 source
|
| Food contact | Not food safe without specific certification (Polymaker) | 1 source
|
| Biodegradability / compostability | Not biodegradable | 1 source
|
| Recyclability | Not accepted in household plastic collection | 1 source
|
| Property and unit | Published value and conditions | Sources and dates |
|---|---|---|
| Fume toxicity (1–5) | Low hazard — minimal VOC and particle emission; TPU was not among the nine filaments in the chamber study | |
| Ventilation / filtration requirement (1–5) | Open a window / occasional ventilation |
| Property and unit | Published value and conditions | Sources and dates |
|---|---|---|
| Sanding & machining | Difficult to sand or smooth; Polymaker limits post-processing to trimming or tumbling | 1 source
|
| Gluing & solvent welding | Cyanoacrylate bonds TPU; no common solvent welds it | 1 source
|
| Vapour / chemical smoothing | No practical vapour smoothing | 1 source
|
| Support material pairing | Polymaker warns TPU supports are often very difficult to remove | 1 source
|
| Dimensional accuracy & detail | Foamed 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 | 2 sources
|
| Property and unit | Published value and conditions | Sources and dates |
|---|---|---|
| Soluble in | DMF, DMSO, NMP and THF dissolve TPU; acetone, MEK and cyclohexanone are partial solvents. All laboratory reagents. | 1 source |
| Softened or crazed by | Toluene and benzene swell it up to +50 % by weight at 23 °C; the foamed wall soaks up esters and alcohols faster still. | 1 source |
| Solvent welding & smoothing agent | None practical — the true solvents (DMF, THF, NMP) are laboratory reagents and leave the joint swollen and weak. | 1 source |
Values describe representative grades, not every spool. Manufacturer datasheets and independent tests retain their source labels and dates. Printed orientation, test method, conditioning and formulation can change results. Unknown values are —. A listed use is not a certification. Shore A, Shore D and Rockwell hardness are separate scales.
Historical USD/kg snapshots. Read each listing’s sale/from qualifiers, spool mass, source date, shipping and tax notes. Product figures are separate from the material summary.
$41.99 / 1 kg spool (black; white $39.99), us.qidi3d.com, Aug 2026
Hardness tunable 85A to 65A by nozzle temperature. QIDI states leakage on travel moves is unavoidable and retraction tuning does not help.
Open product listing ↗| Density (g/cm³) | 0.74 — QIDI lists this under physical properties without saying whether it is the filament or the foamed print |
|
|---|---|---|
| Nozzle temperature (°C) | 230–270 |
|
| Bed temperature (°C) | 30–45 with glue |
|
| Tensile strength (XY) (MPa) | 4.23 ± 0.04 tensile strength and 6.81 ± 0.11 at break (printed XY) |
|
| Elongation at break (%) | 576.27 ± 8.48 at break (printed XY) |
|
| Melting point / Vicat (°C) | 70.4 Vicat softening |
|
$44.99 / 1 kg spool (black; white $43.49), siraya.tech, Aug 2026
85A before foaming. Published property table at four nozzle temperatures: printed density 0.88 g/cm³ and 78 Shore A at 240 °C, 0.51 g/cm³ and 63 Shore A at 270 °C.
Open product listing ↗| Density (g/cm³) | 1.15 filament (ISO 1183); printed part 0.88 at 240 °C to 0.51 at 270 °C (ISO 845) |
|
|---|---|---|
| Tensile strength (XY) (MPa) | 10.3 at break printed at 240 °C down to 3.8 at 270 °C (printed XY, ISO 527) |
|
| Elongation at break (%) | 629 at 240 °C down to 475 at 270 °C (printed XY, ISO 527) |
|
| Hardness (scale-specific) (Shore A / Shore D / Rockwell) | 78 Shore A at 240 °C down to 63 A at 270 °C (ISO 7619) |
|
| Melting point / Vicat (°C) | 83 Vicat at 240 °C down to 53 at 270 °C (ISO 306) |
|
$49.00 / 1 kg spool, phaetus.com, Aug 2026; West3D lists the same spool at $39.99
Active-foaming TPU: flow ratio drops from 0.88 at 240 °C to 0.50 at 270 °C, giving up to 50 % weight saving. Specimens printed with a 0.4 mm nozzle, 45 °C bed, 60 mm/s, 100 % infill, ±45°.
Open product listing ↗| Density (g/cm³) | 1.15 filament (ISO 1183); printed part 0.93 at 240 °C falling to 0.54 at 270 °C (ISO 845) | |
|---|---|---|
| Spool sizes & diameters | 1.75 mm, 1 kg | |
| Nozzle temperature (°C) | 230–270 — the temperature sets the foaming ratio | |
| Bed temperature (°C) | 30–45 | |
| Part cooling fan | On | |
| Maximum volumetric flow (mm³/s; see test conditions) (mm³/s) | Up to 12 maximum extrusion flow | |
| Tensile strength (XY) (MPa) | 9.80 ± 0.42 at break printed XY at 240 °C, 4.77 ± 0.16 at 260 °C (ISO 527) | |
| Elongation at break (%) | 598.7 ± 72.2 at break printed XY at 240 °C, 520.5 at 260 °C (ISO 527) | |
| Hardness (scale-specific) (Shore A / Shore D / Rockwell) | 82 Shore A printed at 240 °C, falling to 66 A at 270 °C (ISO 7619) | |
| Melting point / Vicat (°C) | Vicat 78.8 printed at 240 °C, falling to 50.3 at 270 °C (ISO 306) |
$44.09 / 800 g spool = $55.11/kg, siraya.tech, Aug 2026
Footwear-oriented structural foaming grade. Bayshore rebound holds at 48–50 % across the whole 230–260 °C foaming window. Brass nozzle and open frame are enough.
Open product listing ↗| Density (g/cm³) | 1.05 filament; printed part 0.92 at 230 °C to 0.6 at 260 °C (ISO 845) |
|
|---|---|---|
| Tensile strength (XY) (MPa) | 9 tensile at yield printed at 230 °C down to 4 at 260 °C (printed XY, ISO 527) |
|
| Elongation at break (%) | 760 at 230 °C down to 540 at 260 °C (printed XY, ISO 527) |
|
| Hardness (scale-specific) (Shore A / Shore D / Rockwell) | 80 Shore A at 230 °C down to 66 A at 260 °C (ISO 7619) |
|
$54.90 / 750 g spool = $73.20/kg, recreus.com/en-en (USD storefront), Aug 2026
Recreus states 1.4–1.6× volumetric expansion at optimised settings, run at 60–75 % flow, giving roughly 30–40 % more printed volume per spool.
Open product listing ↗| Spool sizes & diameters | 1.75, 2.20 and 2.85 mm; 750 g, 2.5 kg and 3 kg |
|
|---|---|---|
| Nozzle temperature (°C) | 245–250 (248–252 depending on nozzle size) |
|
| Bed temperature (°C) | Room temperature for small parts; 50–55 for large ones |
|
| Part cooling fan | Off (0 %); 40 % for layers shorter than 10 s |
|
| Maximum volumetric flow (mm³/s; see test conditions) (mm³/s) | 3.5 on a 0.4 mm nozzle; 7.9 on 0.6 mm, 14.0 on 0.8 mm, 21.9 on 1.0 mm |
|
| Drying temperature & time | 55 °C, minimum 1 h |
|
| Hardness (scale-specific) (Shore A / Shore D / Rockwell) | 82 Shore A as extruded, tunable down to 60 A by raising nozzle temperature |
|
$59.70 / 700 g spool = $85.29/kg, colorfabb.us, Aug 2026; the EU store lists EUR 54.20 for the same spool
Foaming activates near 230 °C and expands about 1.6×.
Open product listing ↗| Density (g/cm³) | 1.2 (ISO 1183, unfoamed resin data) |
|
|---|---|---|
| Nozzle temperature (°C) | 195–260 |
|
| Bed temperature (°C) | 50–60 |
|
| Tensile strength (XY) (MPa) | 24 unfoamed at 210 °C, 12 foamed at 230 °C (printed XY, ISO 527-1A) |
|
| Young's modulus (MPa) | 50 unfoamed, 40 foamed (printed XY, ISO 527-1A) |
|
| Elongation at break (%) | 465 unfoamed, 450 foamed (printed XY, ISO 527-1A) |
|
| Flexural strength (MPa) | 3 unfoamed, 2 foamed (printed XY, ISO 178) |
|
| Flexural modulus (MPa) | 50 unfoamed, 40 foamed (printed XY, ISO 178) |
|
| Charpy impact, notched (kJ/m²) | 40 unfoamed, 20 foamed (printed XY, ISO 179, notched) |
|
| Hardness (scale-specific) (Shore A / Shore D / Rockwell) | 92 Shore A unfoamed |
|
| Glass transition (Tg) (°C) | -20 (DSC, ISO 11357, unfoamed resin data) |
|
| Melting point / Vicat (°C) | 130 melting (DSC, ISO 11357, unfoamed resin data) |
|
Carbon-filled hard TPU at 70 Shore D for damping mounts and semi-rigid brackets. Extrudr flags it as the one FLEX grade that…
1 product listing
Below 85 Shore A the filament will not push through anything but a short constrained direct-drive path. Fiberlogy's 81 Shore A…
4 product listingsA styrenic rubber rather than a polyurethane: it needs no drying at all, prints at 260–280 °C and 10–30 mm/s, and trades TPU's…
2 product listingsCompare Foaming / expanded TPU (TPU Aero / TPU Air) with another filament
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