3D Printing InfoFilament comparison
Magnetic vs TPU 85A
Compare printing settings, strength, heat resistance, dated prices and sources.
2 selected · all documented properties
| Property | Magnetic filamentSPECIALTY | TPU 85AFLEX |
|---|---|---|
| Market snapshot | ||
| Listing priceUSD/kg; dated snapshots | $64.99/kg median; $64.99–$64.99/kg across 1 dated product listings | $89.89/kg median; $31.99–$106.05/kg across 6 dated product listings |
| Identity & Market | ||
| Base polymer / chemistry | PLA loaded with ferromagnetic iron powder, so printed parts respond to magnets[1] | Soft thermoplastic polyurethane at 82–85 Shore A[2][3][4] |
| Densityg/cm³ | About 1.85 (Proto-pasta manufacturer figure) — 1.5× standard PLA[1] | 1.11 (BASF Ultrafuse 85A) to 1.19 (NinjaFlex 85A), ISO 1183 / ASTM D792[4][2] |
| Typical priceUSD/kg | 1 kg spools cluster near 65[5] | 1 kg-equivalent spools span 32–106; the middle of the market is about 90[6][7][2] |
| Price range across brandsUSD/kg | 64–70 across formats; 1 kg spool 65, 500 g 70, 2 kg 70[5] | 32–106 across brands; Siraya Tech Flex TPU 85A 32 at 1 kg, add:north TPU Pro Matte 85A 72, Recreus Filaflex 82A 90 at 500 g, Proto-pasta Clear Flexible TPU 90, 3DXTech 3DXFLEX 85A 96, NinjaTek NinjaFlex 106[5][6][7][8][2] |
| Market availability1–5 | Niche, a handful of specialist brands[5] | Available from several mainstream brands[6][5] |
| Spool sizes & diameters | 1.75 and 2.85 mm; 0.1, 0.5, 1 and 2 kg spools[5] | 1.75, 2.85 and 3 mm; 0.5, 1 and 2 kg spools[6][5][2] |
| Typical applications | Sensor targets, magnetic fixtures, and props that need to stick to a magnet or rust deliberately[1] | Soft-touch grips, seals, wearables and anything that must compress and rebound[2][3] |
| Printing Parameters | ||
| Nozzle temperature°C | 192 (Proto-pasta)[1] | 200–220 (BASF Ultrafuse 85A, 210 typical)[4] |
| Bed temperature°C | 60 (Proto-pasta)[1] | 40 (BASF Ultrafuse 85A)[4] |
| Enclosure / chamber requirement1–5 | Open frame is fine[1] | Open frame is fine[4] |
| Bed surface & adhesion aid | Not documented | PEI sheet or painter's tape; Polymaker warns TPU can over-stick and advises a glue stick as a release agent[9][10] |
| Maximum volumetric flow (mm³/s; see test conditions)mm³/s | 1.6–2.4 at Proto-pasta's 20–30 mm/s on a 0.4 mm nozzle at 0.2 mm layer[1] | 1.2–3.2 at the 15–40 mm/s BASF specifies on a 0.4 mm nozzle at 0.2 mm layer[4] |
| Warping tendency1–5 | Not documented | None[4] |
| Bed-adhesion difficulty1–5 | Not documented | Sticks to anything — Recreus states its 82A grade has excellent bed adhesion without a heated bed or additives[3] |
| Stringing / oozing tendency1–5 | Not documented | High — drying plus tuning needed[11][10] |
| Overall printing difficulty1–5 | Intermediate — dry filament and a tuned profile; slow, and brittle in filament form[1] | Advanced — enclosure, hardware upgrades, tuning; at this hardness the filament will not push through a Bowden tube[2][3] |
| Extruder requirement | Proto-pasta advises an extrusion width 0.05 mm larger than the nozzle and warns feeding is inconsistent below 0.4 mm and on Bowden machines[1] | Direct drive only. NinjaTek calls its 85A grade ideal for direct-drive extruders and Recreus specifies direct-drive printers for 82A; BASF caps print speed at 15–40 mm/s with a nozzle of 0.4 mm or larger[2][3][4] |
| Hardware Wear & Reliability | ||
| Nozzle hardness required1–4 | Brass acceptable; hardened steel for volume work[1] | Brass fine indefinitely[12] |
| Abrasiveness1–5 | Moderately abrasive — metal fill[1] | Non-abrasive[12] |
| Nozzle clog risk1–5 | Moderate — needs dry filament and a clean nozzle; Prusa lists metal-filled composites as a higher clogging risk and recommends a 0.6 mm nozzle minimum[13] | High — jams from moisture, heat creep or particles[11][10] |
| Heat-creep / jam sensitivity1–5 | Not documented | Very high — softens in the cold zone readily; soft filament buckles between the drive gear and the melt zone[10][2] |
| Hotend requirement | Proto-pasta recommends a wear-resistant or larger nozzle for longer service intervals[1] | No special hot-end required, but a direct-drive extruder is (Simplify3D)[9] |
| Moisture Behaviour | ||
| Moisture absorption (hygroscopicity)1–5 | Not documented | Moderate — NinjaTek measures 0.22 % in 24 h (ASTM D570) and BASF specifies a 70 °C dry for at least 5 h[2][4] |
| Equilibrium moisture content at ~50 % RH% | Not documented | 0.22 after 24 h water immersion (NinjaFlex 85A, ASTM D570) — an immersion figure, not an equilibrium moisture content at 50 % RH[2] |
| Drying temperature & time | Not documented | 70 °C for at least 5 h in a hot-air dryer or vacuum oven (BASF)[4] |
| Symptoms when wet | Not documented | Bubbling and popping at the nozzle, stringing and a rough surface[11] |
| Effect of moisture on strength | Polymaker rates PLA low-sensitivity and publishes no dry-versus-conditioned figures; absorbed water flashes to steam and shows as bubbling and poor layer adhesion[11] | Polymaker groups TPU with the highly hygroscopic materials; wet TPU prints with poor layer adhesion and weak, brittle layers[11] |
| Storage requirement | Not documented | Sealed with desiccant; often kept in a dryer during the print[11] |
| Mechanical Properties | ||
| Tensile strength (XY)MPa | Not documented | 26 ultimate (NinjaFlex 85A, ASTM D638)[2] |
| Young's modulusMPa | Not documented | 12 (NinjaFlex 85A, ASTM D638) — two orders of magnitude below any rigid filament; NinjaTek's 95A Cheetah reaches 26 by the same method[2][14] |
| Elongation at break% | Not documented | 650 at break (Filaflex 82A) and 660 (NinjaFlex 85A); BASF measures 600 in XY and 320 in ZX[3][2][4] |
| Brittleness1–5 | Brittle — Proto-pasta describes the filament as more brittle than standard PLA and needing extra care in handling[1] | Very ductile — bends far before failing[2] |
| Hardness (scale-specific)Shore A / Shore D / Rockwell | Not documented | 29 Shore D / 85 Shore A (BASF Ultrafuse 85A, ISO 7619-1); 85 Shore A (NinjaFlex, ASTM D2240); 82 A nominal for Filaflex[2][4][3] |
| Creep resistance / sustained load1–5 | Not documented | Poor — no 85A creep test; a printed 95A TPU bar crept from 74.5 to 82.7 mm over 5 days at 1.25 kg, and softer grades creep more[15] |
| Fatigue / repeated-flex resistance1–5 | Not documented | Excellent — living hinges viable[10] |
| Elasticity / flexibility1–5 | Rigid[1] | Rubbery / highly elastic[2][3] |
| Z strength as % of XY% | Not documented | 53 — BASF measures 320 % elongation at break in ZX against 600 % in XY[4] |
| Wear resistance & friction | Not documented | Abrasion 0.08 g mass loss over 10 000 cycles (NinjaFlex, ASTM D4060); 82 mm³ (BASF, ISO 4649)[2][4] |
| Thermal Properties | ||
| Melting point / Vicat°C | Not documented | 216 melting (NinjaFlex 85A, DSC)[2] |
| Environment & Chemical | ||
| UV resistance1–5 | Not documented | Good — years with some colour shift; Polymaker lists UV exposure among the conditions TPU withstands[10] |
| Outdoor durability | Deliberately rustable — Proto-pasta markets the iron content as oxidising when exposed to moisture[1] | Not documented |
| Chemical resistance | Not documented | Withstands industrial solvents and UV exposure (Polymaker)[10] |
| Food contact | Not documented | Not food safe without specific certification (Polymaker)[10] |
| Biodegradability / compostability | Not documented | Not biodegradable[10] |
| Recyclability | Not documented | Not accepted in household plastic collection[10] |
| Electrical & ESD properties | Ferromagnetic: Proto-pasta states it responds to magnets and behaves similarly to pure iron[1] | Not documented |
| Health & Safety | ||
| Fume toxicity1–5 | Low hazard — minimal VOC and particle emission; none of these materials was in the chamber study[16] | Low hazard — minimal VOC and particle emission; TPU was not among the nine filaments in the chamber study[16] |
| Ventilation / filtration requirement1–5 | Open a window / occasional ventilation[16] | Open a window / occasional ventilation[16] |
| Post-Processing | ||
| Sanding & machining | Polishing and deliberate rusting are the intended finishes[1] | Difficult to sand or smooth; Polymaker limits post-processing to trimming or tumbling[10] |
| Gluing & solvent welding | Not documented | Cyanoacrylate bonds TPU; no common solvent welds it[10] |
| Vapour / chemical smoothing | Not documented | No practical vapour smoothing[10] |
| Support material pairing | Not documented | Polymaker warns TPU supports are often very difficult to remove[10] |
| Solvents & Solubility | ||
| Soluble in | Chloroform dissolves the PLA matrix and leaves the iron powder behind; laboratory reagent, not workshop stock.[17][1] | DMF, DMSO, NMP and THF dissolve TPU; acetone, MEK and cyclohexanone are partial solvents. All laboratory reagents.[18] |
| Softened or crazed by | Acetone and ethyl acetate plasticise the matrix rather than dissolving it; water attacks the exposed iron.[17][1] | Toluene and benzene swell it up to +50 % by weight at 23 °C; esters swell it severely; ethanol and IPA soften it.[18] |
| Solvent welding & smoothing agent | None — PLA has no workshop-safe solvent, and the iron loading blocks the surface flow smoothing needs.[17] | None practical — the true solvents (DMF, THF, NMP) are laboratory reagents and leave the joint swollen and weak.[18] |
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
- Magnetic Iron PLA — product page and technical data Proto-pasta · 2026-08 · tds
- NinjaFlex 85A Technical Specifications NinjaTek · 2026-08 · tds
- Filaflex 82A product page (Shore hardness and elongation) Recreus · 2026-08 · vendor
- Ultrafuse TPU 85A Technical Data Sheet (Version 3.0) BASF Forward AM · 2022-08 · tds
- Proto-pasta product catalogue Proto-pasta · 2026-08 · vendor
- 3DXTech product catalogue 3DXTech · 2026-08 · vendor
- Siraya Tech Flex TPU 85A Filament — product page Siraya Tech · 2026-08 · vendor
- add:north TPU Pro Matte 85A product page add:north · 2026-08 · vendor
- Flexible (TPE/TPU) — Ultimate 3D Printing Materials Guide Simplify3D · 2026-08 · doc
- TPU — material basics Polymaker Wiki · 2026-08 · doc
- Wet Filament — signs, causes and drying Polymaker Wiki · 2026-08 · doc
- Extrudr Product Catalogue (DURAPRO PA12 data block) Extrudr · 2025-03 · tds
- Composite materials with metal or wood particles Prusa Knowledge Base · 2026-08 · doc
- NinjaTek technical specs comparison chart (Cheetah, NinjaFlex, Armadillo, Alloy 910, Nylon 645) NinjaTek · 2026-08 · tds
- BambuLab TPU 95A HF vs Qidi TPU 95A HF — results spreadsheet My Tech Fun (Igor Gaspar) · 2024-02 · test
- 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
- Solubility Study of Ingeo Biopolymer Grades in Common Organic Solvents (NWPD003) NatureWorks · 2019-10 · tds
- Elastollan — Chemical properties: swelling and chemical resistance BASF · 2026-08 · tds