High-impact polystyrene is what you get when you disperse a rubbery polybutadiene phase through ordinary polystyrene. Plain polystyrene is brittle enough to snap in your fingers; the rubber phase absorbs the energy of a crack tip and stops it propagating, which turns a fragile plastic into the material of yoghurt pots, refrigerator liners and model railway scenery.
On a printer, though, HIPS is bought overwhelmingly for a property that has nothing to do with impact: it dissolves in d-limonene.
The solvent is citrus, not water, and this trips people constantly
The single most common HIPS mistake is expecting it to wash off under a tap. It will not. HIPS is a hydrocarbon polymer and water does not touch it. What dissolves it is d-limonene, the terpene solvent pressed from citrus peel — the stuff that makes orange oil cleaner smell of oranges.
Working with it is slower and more involved than the water bath people imagine:
- It takes hours, often overnight, and warmth and agitation both help substantially.
- The bath saturates. Limonene that has already dissolved a lot of HIPS works progressively more slowly, so a large support volume needs fresh solvent partway through.
- It is not cheap, and it evaporates.
- It is flammable and a known skin sensitiser. Gloves, a lid, and ventilation — the same care you would give any organic solvent, in spite of the pleasant smell.
If the requirement is genuinely water-soluble support, that is PVA or BVOH, and the PVA against BVOH comparison covers which. HIPS exists for a different reason.
Why it pairs with ABS specifically
Support material only works if it prints at the same temperature as the model material and bonds to it enough to hold but not so much that the interface tears. HIPS runs at 230 to 250 °C with a bed at 90 to 110 °C — squarely inside ABS's envelope — warps at a similar rate so both materials stay on the plate together, and shares enough styrenic character with ABS to stick without welding.
That similarity is why HIPS is the standard second spool on a dual-extrusion machine printing ABS, and why it is a poor partner for PLA, whose temperatures it does not share.
What the second spool costs
Support material is not free, and people leave it out of quotes because it does not end up in the part. So price the HIPS half of a dual-material job on its own: the 90 g of scaffolding, and the 3 extra hours it adds to the run.
| Term | Assumption | Cost |
|---|---|---|
| Filament | 90 g at $25/kg | $2.25 |
| Machine time | 3 h at $0.40/h | $1.20 |
| Electricity | 0.45 kWh at $0.175/kWh, enclosure drawing 150 W | $0.08 |
| Failure allowance | 8% | $0.31 |
| Support subtotal | $3.84 |
That is before a drop of limonene has been bought.
Ninety grams of HIPS across three hours, which is what the print cost calculator opens with, is a modest interface on a medium part rather than a full soluble shell. The machine-time term is the one that surprises people: soluble support is usually printed slowly and with dense interface layers, so it consumes hours out of proportion to its mass.
Printing it on its own
HIPS is perfectly printable as a model material and behaves like a slightly softer, lighter ABS. Same enclosure requirement, same aversion to draughts, same hot bed with an adhesive layer, same fan-off approach. Shrinkage of 0.4% to 0.7% sits just under ABS's, so a large flat HIPS part will still lift given the chance.
Where it is genuinely pleasant is afterwards. It sands easily and evenly without the gumming that plagues PLA, takes filler and primer well, and glues with ordinary polystyrene cement — the same tube used for scale model kits, which welds it properly rather than sticking to it.
What HIPS is genuinely bad at
- Being a structural material. Tensile strength of 20 to 35 MPa is the lowest of the styrenics and below PLA by a wide margin. It is light and tough-ish, not strong.
- Chemical resistance. With no acrylonitrile in the mix it is attacked by oils, fuels and many solvents that ABS shrugs off — and by the very limonene that makes it useful.
- Heat. Deflection between 80 and 95 °C is respectable against PLA and below ABS.
- Sunlight. The same butadiene phase that gives ABS its outdoor problem gives HIPS the same one.
- Any workflow without limonene. If you are not set up to dissolve it, its main advantage is unavailable and there are better materials for everything else.
- Fume-free rooms, since it is a styrenic and smells like one while printing.
Where it earns a place on the shelf
Soluble support for ABS assemblies with internal cavities, captive parts and enclosed mechanisms. Lightweight RC airframes and gliders, where its low density and good stiffness-to-weight matter more than absolute strength. Model bases, scenery and dioramas destined to be sanded, filled and painted. Vacuum-forming bucks, since it is the same polymer the sheet is made of.
The misuse worth naming is printing a functional bracket in HIPS because it was cheap and the spool was already loaded. It will feel adequate in the hand and fail early under load, and the version in ABS — same printer settings, same enclosure — would have been the right part.