What Prusa launched
Ultraglow is a PETG base filled with the highest possible load of strontium aluminate, the glow pigment that Prusa notes is a safe alternative to older phosphorus-based options. It charges under light, most effectively UV, then glows strongly for the first several minutes before the intensity tapers. Prusa says a weak glow can remain visible six to eight hours after charging, which is what earns the "brightest on the market" claim. It launches in green, with more colors described as on the way.
Pricing lands at a premium: an 800 g spool is 82.99 dollars with import duties included, or 69.99 euros. Note the 800 g spool weight rather than a full kilogram, which matters when you compare it on price per kg against ordinary PETG.
The catch: it eats nozzles
Glow pigment is essentially fine ceramic, and packing in the maximum load makes Ultraglow extremely abrasive. Prusa is blunt about it: a hardened nozzle is required, and the filament will destroy a brass nozzle in no time. That puts Ultraglow in the same handling category as carbon-fiber and other filled filaments, where a hardened or wear-resistant nozzle is not optional.
What this means for buyers
If you print signage, cosplay, or props where a strong, long-lasting glow is the point, Ultraglow delivers more than a standard glow PLA. Budget for a hardened nozzle before your first spool, because a brass nozzle will wear out fast. Charge the print under UV for the strongest effect. If you only need a mild glow on a quick print, a cheaper glow-in-the-dark PLA is gentler on your hardware and your wallet.
Where it fits
Ultraglow is a specialty spool, not an everyday PETG. The live Prusament listings show where it sits on price, and the full PETG listings put its per-kg cost next to standard PETG so the premium is easy to see.
For how PETG behaves as a base material before the glow pigment goes in, the PETG filament guide covers its strengths, its stringing habits, and the settings that tame it.