PVA (FDM)

PVA printed by fused deposition modeling is a water-soluble thermoplastic extruded from filament, used mainly as a sacrificial support material rather than for structural parts. It is usually run through a second nozzle alongside a structural thermoplastic, so supports can be printed in contact with complex geometry. It absorbs moisture readily, so filament must be kept dry to avoid bubbling, stringing and rough surfaces. After printing, the part is soaked in water and the PVA dissolves, leaving surfaces free of the marks left by mechanical support removal. It is used for supports under overhangs, inside internal cavities and in interlocking assemblies that cannot be cleaned out by hand.