Prusa Launches PETG Ultraglow: The Brightest Glow-in-the-Dark Filament

What Prusa Announced

Prusa Research has launched Prusament PETG Ultraglow Green, a glow-in-the-dark filament they're calling the brightest on the market. The key: it's filled with the maximum possible amount of strontium aluminate while still being printable.

Why It's Different

Most glow-in-the-dark filaments are PLA-based with modest glow compound content. Prusa went a different direction: PETG base (stronger, better temperature resistance) and maximum strontium aluminate loading. The result is a filament that doesn't just glow — it genuinely illuminates nearby surfaces in darkness.

Prusa tested it against competing glow filaments and published comparison photos. The difference is significant — Ultraglow is noticeably brighter, maintaining visible glow for 6-8 hours after a full charge.

The Trade-offs

Prusa is transparent about what this filament demands:

• Highly abrasive: Strontium aluminate is the hardest material Prusa has ever used in a filament. Hardened steel nozzle required — brass won't last.
• Wear concerns: Accelerated wear on printer components should be expected. This isn't everyday filament.
• 0.6mm nozzle recommended: The powder loading is high enough that a larger nozzle helps reliability.

Price and Availability

Available now from Prusa: 800g spool for €69.99 (VAT included) or $82.99 USD (import duties included). Currently green only, with additional colours promised.

Sample spools (25g) available for testing before committing to a full roll.

Use Cases

Beyond decorative prints, Prusa highlights functional applications:

• Switches, handles, and indicators that need visibility in darkness
• Multi-material prints with glowing accents (XL/MMU)
• Safety markers and emergency signage
• Outdoor markers for camping or navigation

The Honest Take

This is premium filament at a premium price — roughly 3x the cost of standard PETG. The abrasive nature means you'll wear through nozzles and potentially other components faster. But if you need serious glow performance and aren't satisfied with existing glow filaments, Ultraglow delivers on its claim.

The PETG base is a smart choice over PLA — functional parts can actually be functional, with better temperature resistance and strength. Combined with the XL's multi-material capability, you could print structural parts in regular PETG with glowing accents only where needed, saving the expensive filament for visible details.

For occasional decorative prints, the cost and wear probably aren't worth it. For functional parts where visibility matters — emergency equipment, outdoor gear, night-time accessibility — it's a legitimate tool.