The Shore A scale tops out at 100, and at 98A there is not much of it left. A part in this material does not squash between your fingers; it bends stiffly, springs back hard, and feels closer to a stiff shoe sole than to a rubber band. Calling it a flexible filament sets the wrong expectation and sends people away disappointed.
What it actually is: a thermoplastic polyurethane tuned to sit right at the boundary between elastomers and rigid plastics, with the abrasion resistance and energy absorption of a rubber and enough stiffness to hold a shape under load.
Why it prints so much more easily than softer grades
Flexible filament fails in the extruder because the unsupported length between the drive gear and the melt zone acts as a column under compression, and a soft column buckles. Stiffness is what resists buckling, and at 98A there is enough of it that the filament behaves close to a rigid one.
The practical consequences are large:
- Bowden setups can print it. Not perfectly, and not fast, but a long PTFE path that would defeat 95A is workable here. It is the only flexible most Bowden owners will get results from.
- Speeds are reasonable. Where softer grades are pinned to 20 to 35 mm/s, 98A tolerates a good deal more, which changes the economics of a job entirely.
- Retraction works. The filament does not stretch appreciably under retraction force, so ordinary retraction settings recover ooze instead of merely pulling on elastic.
This is why the data on this site rates it as the easiest material in the flexible family by a wide margin, and why it is the sensible first flexible spool rather than the softer grade most people are tempted by.
What it is for
Parts that must absorb energy without deforming permanently. A drone landing skid that takes a hard arrival and springs back. A bumper on a machine that gets knocked. A wheel that grips without squirming under torque. A semi-rigid bracket that has to tolerate misalignment during assembly. Watch and tool straps that hold their shape.
Its abrasion resistance is where it quietly excels. Polyurethane elastomers outlast most rubbers against sliding wear, so a 98A wear pad, guide or roller lasts far longer than a printed rigid one and does not chew up what it runs against.
Temperatures, drying and the plate
Everything runs slightly hotter than the softer grade, because a stiffer formulation is more viscous in the melt: 225 to 250 °C through the nozzle, 30 to 60 °C on the bed, no enclosure.
Dry it: 4 to 6 hours at 60 °C. Wet polyurethane bubbles in the nozzle and leaves a furry, pitted surface, and this is the single most common complaint about every TPU grade. It is also entirely fixable, which is not true of most filament complaints.
Bed adhesion tends toward too much rather than too little, exactly as with the softer grades. A textured sheet is the safe default; a smooth plate can bond a TPU first layer down hard enough to make removal a fight.
Weighing what is left
Flexible filaments are frequently sold on 500 g reels and other part-kilogram sizes rather than the kilogram reels everything else uses, and the reels themselves are often a different plastic and a different weight from the ones you are used to. That makes "how much is left" harder to guess than usual, and guessing wrong on a long print is expensive — a flexible filament join partway through a print is not something you can splice, because the two ends will not weld reliably under a hot-end clip.
Weigh it instead. A part-used 98A reel showing 640 g gross on the scale, with a 215 g empty reel, holds 425 g of filament — 146.03 m at a density of 1.21 g/cm³, or 17 more prints at 25 g each. The 215 g in the length and weight converter is a full-size plastic reel, and the reel under a 500 g flexible spool will not weigh anything like that — which is exactly the error weighing is supposed to remove. Write the empty weight on the reel the first time you find it, because you will need it again.
What TPU 98A is genuinely bad at
- Being soft. If the requirement is a squashy grip, a compliant seal or a cushioning pad, this material will disappoint you and no setting changes that. That is a job for 85A.
- Bridges and steep overhangs. The melt stays soft and droops, and supports fuse stubbornly to a flexible surface.
- Fine detail. Sharp corners round off, and small holes come out undersized.
- Precise dimensions. Elastic recovery continues after the print, so a part measured cold and measured tomorrow differ slightly.
- Speed at the level rigid filaments manage. Easier than other flexibles is not the same as easy.
- Sunlight, in the common aromatic formulations, which yellow. The part keeps working; it stops looking new.
Choosing between the grades
The useful question is not "how flexible do I want it" but "does the part need to hold its shape under load". If it does, 98A. If the part's job is to deform — to seal, to cushion, to grip a curved surface — then you want a genuinely soft grade and you should plan for a slower, more difficult print.