The Promise of Perfect Supports
By Inno Uncle
The idea is seductive: print complex geometry with dense support material that you dissolve away in water or chemicals, leaving a perfectly clean part with zero support scars. Dual-extrusion printers have been promising this for years. The reality is more complicated — but when it works, it genuinely unlocks geometries that are impossible any other way.
PVA: Water-Soluble and Finicky
Polyvinyl alcohol (PVA) dissolves in plain water. It's the support material most hobbyists encounter first because it sounds so simple — just soak the print and the supports vanish. Here's what the marketing doesn't tell you:
PVA is absurdly moisture-sensitive. Leave a spool out for 24 hours in 50% humidity and it becomes unprintable — it pops, sizzles, and extrudes unevenly. You need active drying (a filament dryer running during the print) or a sealed dry box feeding directly to the extruder. A filament drying box running during PVA prints is not optional — it's essential.
PVA also doesn't bond well to PETG or ABS. It's primarily compatible with PLA (both print at similar temperatures). The interface layer between PVA support and PLA part needs to be dialed in precisely — too close and the support welds to the part, too far and the supported surface sags.
Dissolution time varies wildly. A dense PVA support block in a narrow cavity can take 12+ hours in static water. Agitated or heated water (40°C) cuts this to 3-4 hours and is strongly recommended.
HIPS: The ABS/ASA Solution
High Impact Polystyrene (HIPS) dissolves in limonene (d-limonene) — a citrus-based solvent that smells pleasant and is relatively safe to handle. HIPS is the go-to support for ABS and ASA because it prints at similar temperatures (230-245°C) and bonds well to styrene-based materials.
Unlike PVA, HIPS is far less moisture-sensitive. You still want to keep it dry, but a sealed bag with desiccant is usually sufficient. The bigger challenge is limonene disposal — it can't go down the drain, and the dissolved HIPS/limonene solution needs to be taken to a hazardous waste facility or evaporated outdoors. Factor this into your workflow.
HIPS as a dedicated support interface (just the layer touching the part, with cheaper material for the support body) is the smart approach. Print the bulk of the support in ABS and use HIPS only for the contact layer. This saves money and speeds up dissolution.
Do You Actually Need Soluble Supports?
For 95% of hobby prints, the answer is no. Modern slicers produce breakaway supports that leave acceptable surfaces if you tune the support interface properly (0.2mm Z-distance, 75% interface density). The time and cost of dual-extrusion soluble supports rarely justify the marginal improvement in surface quality.
Where soluble supports earn their keep: internal channels that can't be cleaned manually, parts with complex internal cavities, and production parts where manual support removal would take too long. If you're printing dental models or engineering prototypes and need pristine surfaces, explore our resin collection — SLA printing often handles these geometries more cleanly than FDM with soluble supports ever will.
For most makers, mastering standard support settings and a good set of post-processing tools from our accessories collection will get you 90% of the way there without the PVA headaches.