Solubles
When 3D printing, supports are often required for models with overhangs or limited contact with the print bed. Supports can be added during slicing or in the modeling stage. Supports are necessary when, for example, a model has branch elements leaving the body of the object at an angle more than 45 degrees from the vertical. Supports are also needed when a horizontal surface occurs at some point above the printing surface.
Supports are typically made from the same material as the model, but soluble support materials have benefits by way of ease of removal and reduced effect on print quality.
Solubles:
Choosing a soluble support material involves assessment of cost, environmental impact, and compatibility with the main material. While some soluble support materials are expensive, the ability to remove them without harming the model can outweigh the cost in certain situations. The solvent used must be safe for both users and the environment.
Soluble material is often quite expensive and for this reason must be used only when absolutely necessary. Soluble supports are most often used when surface scarring is a completely unacceptable outcome. For example, a figurine type object, requiring a smooth surface on every angle.
Using soluble supports requires a multi-material capability. When using a single extruder, the support material should have similar printing temperatures to the main material. In multi-extruder setups, this constraint is relaxed, but the support material should still adhere slightly to the main material.
Five materials for soluble supports are held in stock, and here are their characteristics:
1. PVA (Polyvinyl Acetate): It's water-soluble, eco-friendly, and similar to PLA in printing characteristics. But really difficult to print.
2. PVB (Polyvinyl Butaride): Soluble in Isopropyl alcohol (IPA) and similar to PLA in printing characteristics. Easier to print.
3. HIPS (High Impact Polystyrene): With high-temperature properties, it's soluble in d-Limonene, an environmentally friendly solvent. It can be used as a support material for ABS and ASA.
4. ASA (Acrylonitrile Styrene Acetate): Soluble in Acetone. Also with high-temperature characteristics, it can serve as a support material for materials like PA and PC.
NOTE: Both HIPS and ASA can also be used either as primary modeling materials or as supports for other materials.
5. BVOH (butanediol vinyl alcohol) : Water Soluble. Used with ABS, ASA and PLA. It has similar printing characteristics to PLA.
Non-Solubles:
The most common material to use for supports is the primary printing material - acting as its own supports. The drawback of so doing is that the supports can bind to the model, and removal can damage the surface.
So its becoming more common to see materials having dissimilar chemistry used to make supports. In such cases, the support material does not bind as much to the main material, and so when removed mechanically it comes away easily, leaving less surface scarring and not requiring the solvent step.
