Because a single-nozzle printer has to purge the old colour from the hotend at every change, into a waste chute or a purge tower. Designs with frequent colour changes on many layers multiply that purge, which also adds time to each change.
Multicolour printing on a single nozzle trades filament and time for colour.
Why multicolour printers purge
When the colour changes, the hotend still holds melted filament of the previous colour. The printer pushes new filament through until the colour runs clean, discarding the mixed plastic as purge — into a chute or a purge tower on the plate.
What increases multicolour waste
Many colour changes per layer. Tall prints where colours change on every layer. Dark-to-light changes, which need more purge. Several small multicolour parts on one plate.
Reducing purge in multicolour prints
Tuned purge volumes by colour pair in the slicer. Purging into infill where colour does not show. Designing colours on fewer layers, such as flat inlays near the top. Grouping parts to share changes.
Multicolour hardware that avoids purging
Tool-changers and multi-nozzle printers load each colour in its own nozzle. They cost more and purge far less.
Counting multicolour time
Each change adds unload, load and purge time; slicer estimates include it, and multicolour estimates are often much longer than single-colour ones.
If this page and the manufacturer’s manual disagree, follow the manual. Every laser power, speed, build volume, resolution, temperature and safety rating on this page is taken from the maker’s own documentation, with its unit as published and its source named — none of it is measured here. A figure is written the way the maker states it and is not converted into another convention, because the converted value would be a different number. And for any print speed: a published maximum speed describes what the motion system can reach, not how fast a good part is printed. The speed that works depends on the material, the geometry, the cooling and the slicer profile. This page quotes the maker’s figure as a maximum and draws no print time from it.
Questions makers ask before buying
Can the purge be reduced?
Slicers let purge volumes be tuned by colour pair, use infill to absorb some purge, and group colours to reduce changes. The printer maker’s defaults are a starting point.
Do printers with several nozzles waste less?
Tool-changing or multi-nozzle printers avoid most purging because each colour has its own nozzle, which their makers cite as the main advantage.
Last reviewed 15 September 2026