Spectrum ReFill LW-PLA UltraFoam Persian Blue, 1,75 mm / 750 g

ReFill LW-PLA UltraFoam by Spectrum is a spool-less filament wound onto a cardboard core, compatible with reusable Bambu Lab spools and self-printed Spectrum spools* – no additional adapters required. This environmentally friendly solution generates virtually no waste and comes at an affordable price!

*Click here to download the STL files for printing your own Spectrum spools.

Spectrum LW-PLA UltraFoam is a specialised filament based on Spectrum Premium PLA, which uses active foaming technology to achieve a significant reduction in material weight. It is particularly suitable for lightweight applications requiring mechanical strength, low weight, and a clean surface finish – such as in model making, UAV components, or functional prototypes.

The filament contains additives that trigger a controlled volumetric expansion at defined printing temperatures. The foaming process starts at around 220 °C, with maximum expansion reached between 240 °C and 250 °C. At lower temperatures (below 220 °C), the material behaves like conventional PLA and can be processed accordingly. In the fully foamed phase, the filament achieves:

• Volume increase: more than 3×
• Extremely low density: approx. 0.40 g/cm³
• Flow reduction: up to 70% possible

The degree of expansion can be controlled via the printing temperature, allowing the density of the printed object to be precisely adjusted. This feature makes it suitable for both structural lightweight parts and aesthetically demanding applications. The matte surface also ensures a visually uniform and technically clean part finish. As the foaming increases, the material’s colour lightens – a visual effect that should be taken into account when designing visible parts.

Key features at a glance:

• Matte surface finish
• Active foaming technology
• More than 3× weight reduction during printing
• Adjustable material density via full control of flow and structure
• Very low final density

Tips:

► Expansion rate may vary depending on the printer model.
► Printers with an enclosed build chamber may achieve higher levels of foaming.
► Moisture affects foaming behaviour – drying before printing is recommended.
► Increased retraction helps to reduce stringing.
► If models are difficult to remove from the build plate, try lowering the bed temperature.
► For brittle prints, increasing the flow rate is advised.