LW-PLA filament guide
LW-PLA, short for lightweight PLA, is usually PLA with a foaming agent mixed in. When it is heated past a certain point in the nozzle, it expands like a foam, so each line of plastic takes up more space for the same weight. Dial the flow down to match and you get parts that weigh a fraction of a normal PLA print, which is why RC plane builders and cosplayers love it.
How the foaming works
Below its activation temperature, an active foaming LW-PLA prints like ordinary PLA. Above it, around 230°C for colorFabb's version, the foaming agent expands the plastic as it leaves the nozzle, and the hotter you print, the more it expands, up to a limit set by the formula. colorFabb quotes weight savings of up to 65 percent compared with solid PLA at full expansion.
The one thing not to get wrong
With an active foaming LW-PLA, foaming only saves weight if you reduce the flow rate to match the expansion. Print at a foaming temperature with normal flow and you get an overextruded, blobby part with no weight saving. Always pair a higher temperature with a lower flow setting.
Not every LW-PLA works this way. Polymaker's PolyLite LW-PLA is pre-foamed at the factory, so it prints at normal PLA temperatures of around 190 to 210°C with no flow adjustment. It is simpler to use but saves less weight than an active foaming filament at full expansion.
Printing it
Follow the temperature and flow chart from your spool's maker, since activation temperature and expansion differ between brands. The usual approach is to pick a temperature for the amount of foaming you want, print a single wall calibration cube, and lower the flow until the wall thickness matches what your slicer expects.
Foamed plastic keeps expanding as it leaves the nozzle, so LW-PLA oozes and strings more than normal PLA. Tune retraction and travel, and expect to do a little cleanup. Surfaces come out matte and slightly rough, which suits props that will be primed and painted.
When to choose LW-PLA
Choose LW-PLA when weight matters more than strength: RC plane wings and fuselages, large cosplay armor and helmets, big display props and anything worn or carried for hours. Foamed parts are noticeably weaker and softer than solid PLA, so skip it for load bearing or functional parts.
Like all PLA, it softens around 55 to 60°C, so keep finished props out of hot cars. For more on props, see the best filament for cosplay and props, and the PLA filament guide covers the fundamentals.
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LW-PLA is listed with the rest of the PLA family. Compare live PLA listings by brand, weight and price per kg.
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