PVA vs. HIPS: Choosing a Dissolvable Support Material for Complex 3D Prints
3 min reading time
Get to know PVA and HIPS, soluble support materials for complex 3D prints, plus how to choose the right one for PLA, PETG, or ABS.
Why Use Soluble Support Material?
3D prints with complex structures, such as parts with internal cavities, sharp overhangs, or moving parts, often rely on support material during printing. However, manually removing support made from the same material as the main part often leaves rough marks or cannot reach deep, hidden spots. This is why PVA and HIPS were developed as "Soluble Support Materials" for use with dual-extrusion 3D printers, allowing for perfectly smooth surfaces without manual removal.
This article will delve into PVA and HIPS in detail, covering their properties, usage, and criteria for choosing the right one for your projects.
What is PVA (Polyvinyl Alcohol)?
PVA is a water-soluble plastic suitable for use as support material with PLA or PETG filaments because their printing temperatures are similar. The method of use involves printing support with PVA alongside the main part, and after printing is complete, submerging it in warm water to dissolve the support, leaving behind a smooth, blemish-free part.
The most crucial point to watch out for is PVA's extremely high sensitivity to moisture, much higher than common plastics. Simply leaving a spool in an area with 50% humidity for 24 hours can cause the filament to absorb moisture, leading to printing failures, popping sounds during extrusion, and inconsistent prints. Therefore, PVA should be stored in a dry box with silica gel or used with a filament dryer operating continuously during printing.
For dissolving thick support material in narrow cavities, static water immersion can take over 12 hours. However, using warm water at around 40 degrees Celsius with gentle stirring or agitation can reduce the time to just 3-4 hours.
What is HIPS (High Impact Polystyrene)?
HIPS is a strong and impact-resistant plastic commonly used as support material with ABS filament due to their similar printing temperatures and shrinkage behavior. Unlike PVA, HIPS is not water-soluble but dissolves in a chemical called D-Limonene, which is extracted from orange peels, has a mild fragrance, and is safer than other chemical solvents.
The advantages of HIPS include its lower moisture sensitivity compared to PVA, making it easier to store. When printed with ABS in an enclosed chamber, it effectively reduces warping issues during printing. Furthermore, there's no need to print an Ooze Shield to prevent filament contamination, unlike when using chemically incompatible support materials.