HIPS HIPS (high-impact polystyrene) support material

HIPS, high-impact polystyrene, is the same family of plastic used for yogurt cups, packaging trays and many disposable items, toughened with a little rubber. In 3D printing, it is best known as a support material. Supports are the temporary scaffolding a printer builds under overhangs and inside cavities, and HIPS is used because it can be dissolved in d-limonene, a citrus-derived solvent, instead of being snapped or cut away.

HIPS prints at temperatures similar to ABS, so it has traditionally been paired with ABS on multi-material printers: the part is printed in ABS, the supports in HIPS, and the supports are removed afterwards. On our QIDI Max4 and Plus5, HIPS runs through the QIDI Box, which QIDI lists as supporting HIPS. Because it is paired with ABS, we print it in the same closed, heated chamber.

There is an important caveat. Prusa's materials guide warns that ABS and ASA also partially dissolve in limonene, and that over-exposure can ruin some ABS or ASA parts. In practice, we use HIPS with ABS in a controlled way: we test the specific ABS grade, keep soaks short and supervised, and often break away most of the HIPS by hand first. HIPS can also print standalone parts, but that is not why you'd choose it, so this page treats it mainly as a support.

As a standalone material, HIPS is modest. Fiberlogy's datasheet lists 25 MPa tensile strength at yield and a tensile modulus of 1,850 MPa, both well below ABS. It is fairly tough for its weight: Fiberlogy reports 31% elongation at break and a notched Charpy impact strength of 12 kJ/m², so HIPS parts tend to bend before they snap. Prusa's guide calls it relatively soft, with moderate mechanical properties and good dimensional stability.

As a support, these properties matter in a different way. HIPS needs to be stiff enough to hold up the overhang and well enough bonded to stay in place during printing, but not so firmly bonded to the ABS part that it can't be removed. Because HIPS and ABS print at similar temperatures and shrink similarly, they work well together in the same build.

Like any FDM material, HIPS is weaker between layers than along them. For supports, that is a benefit: the layered structure breaks apart more easily when we remove it. For a standalone HIPS part, it means the same orientation care as any other material applies.

Fiberlogy lists a heat deflection temperature (HDT) of 83 °C at 0.45 MPa and 74 °C at 1.80 MPa for its HIPS, with a Vicat softening temperature of 74 °C. HDT is the temperature where a standard test bar bends a set amount under load, and Vicat is the temperature where a loaded needle sinks a set depth into the surface. These values put HIPS a little below ABS.

For HIPS as a support, its heat resistance matters mostly during printing: it must not sag in a warm chamber while the ABS part builds on it. For standalone HIPS parts, treat it as similar to or slightly below ABS in heat tolerance, and don't anneal it.

Polystyrene has poor UV resistance and degrades in sunlight, turning yellow and brittle. Standalone HIPS parts are for indoor use only. As a support, its UV behavior does not matter because it is removed.

HIPS dissolves in d-limonene, which is the whole point of using it as support; Fiberlogy and Prusa both describe this. Prusa also notes it dissolves in acetone, very quickly. Generally, polystyrene is attacked by many solvents, fuels and oils.

Here is the trade-off for buyers: ABS and ASA can also be partly dissolved by limonene. Prusa's guide warns that over-exposure can disrupt layer adhesion and make a model fall apart, citing a specific ASA. That is why we control soak times, test each ABS grade first, rinse parts thoroughly, and never use HIPS as support for ASA.

HIPS absorbs only a little moisture, though it benefits from drying before printing. Fiberlogy recommends 60 °C for 4 hours. Dry filament gives cleaner support interfaces, which in turn gives cleaner surfaces on your ABS part.

Once printed, HIPS is dimensionally stable in normal humidity. For standalone parts, water does not harm HIPS, but limonene residue from support removal needs to be rinsed off and the part dried; Prusa notes a lasting citrus smell is possible.

Where HIPS supports touch an ABS part, the surface is usually cleaner than with breakaway supports in the same material, because the two materials separate along a distinct interface. You may still see a slightly matte or textured patch where supports were.

Standalone HIPS has a matte, slightly chalky surface. Fiberlogy notes it can be sanded, glued and painted with acrylic paints, which suits display models.

Support removal: we break away as much HIPS as can be reached by hand, then dissolve what's left in d-limonene with a short, supervised soak for the ABS grade we have tested. Parts are then rinsed and dried. Removal adds time, which is reflected in the quote.

Residue and smell: limonene can leave an oily residue and a citrus smell. We rinse parts, but a faint smell can linger for a while.

Standalone parts: HIPS sands easily and takes acrylic paint. Smoothing with solvents isn't something we offer for HIPS.

Threads and inserts: in standalone HIPS parts, heat-set inserts work but the soft material holds less torque than ABS. Avoid tapped threads for anything load-bearing.

Soluble support helps most with internal geometry: channels, threads inside bores and sealed-looking pockets come out closer to the model because nothing has to be pried out with a tool. Where support has been removed, surfaces can be slightly rougher or matte compared with the rest of the part.

Prusa notes HIPS shrinks much less than ABS, so supports built in HIPS stay put and hold up overhangs consistently. That stability is part of why HIPS works well for supporting large ABS overhangs.

With HIPS supports, undersides of overhangs and internal cavities can come out closer to the designed shape than with breakaway supports, because there is less tearing during removal. Expect the usual FDM tolerances on the ABS part itself, with holes printing slightly undersized.