The duration that luminous (glow-in-the-dark) filament glows depends on several factors, but generally, it can range from minutes to several hours. Here's a breakdown of what influences the glow:

• Type of Phosphorescent Material: Most modern glow-in-the-dark filaments use strontium aluminate, which glows much longer and brighter than older materials like zinc sulfide. The quality and concentration of this phosphorescent powder in the filament greatly affect its performance.

• Charging Light Source and Duration:

  • UV light is the most effective for charging, as it provides strong energy. A few minutes of exposure to UV light or direct sunlight can achieve a significant glow.

  • Regular indoor lights can also charge the filament, but the glow may be less intense and shorter-lived.

  • The longer and more intensely the filament is exposed to a light source, the brighter and longer it will glow.

• Color of the Filament:

  • Green glow-in-the-dark filaments are typically the brightest and glow the longest.

  • Blue filaments are generally less bright and don't last as long as green.

  • Red and other colors often glow for a much shorter duration and with less intensity.

• Thickness of the Print: Thicker prints or objects with more glow-in-the-dark material tend to glow longer because they contain more phosphorescent particles to store and release light.

• Ambient Darkness: The glow is most noticeable in complete darkness. Even faint ambient light can make the glow seem to fade faster.

• Brand and Quality: Different filament brands use varying formulations and concentrations of glowing pigments. High-quality filaments will generally perform better and for a longer duration.

In summary: While the initial brightness of a luminous filament can decrease rapidly in the first hour or two, a good quality green glow-in-the-dark filament, adequately charged, can remain visibly glowing for several hours, even up to 8-10 hours in a very dark room, although at a significantly diminished intensity.

Generally, yes, you can trim LED filament to length, but it's not as simple as cutting any piece of wire. Here's what you need to know:

• Look for designated cut lines: Just like standard LED strip lights, some LED filaments are designed with specific "cut lines" or "solder pads" at regular intervals. These are the only safe places to cut, as they mark the end of one circuit segment and the beginning of another. Cutting elsewhere will likely break the circuit and render a portion (or all) of the filament unusable.

• Specialized filaments: Some manufacturers specifically offer "trimmable" LED filaments for DIY projects. These will have clear markings and instructions on where and how to cut them.

• Requires soldering: To shorten a flexible LED filament, you'll typically need soldering skills to re-connect power to the cut section. You'll expose copper contacts at the cut point and solder wires to them.

• Polarity matters: LED filaments have a positive and negative end. You'll need to identify these (often marked, or one end might have a small hole) to ensure proper connection after cutting.

• Protect the joint: After soldering, it's crucial to insulate and protect the connection to prevent short circuits and ensure durability. Heat-shrink tubing or electrical tape are common methods.

• Voltage considerations: When shortening a filament, remember that the original power supply was designed for the full length. If you shorten it significantly, you might need to adjust the power supply or add resistors to ensure the correct voltage and current for the new length, preventing damage to the LEDs.

In summary: While it's possible to trim some LED filaments, it requires careful attention to detail, the right tools (sharp scissors, soldering iron), and an understanding of basic electronics to ensure the filament remains functional and safe. If you're unsure, it's often best to purchase filaments in the exact lengths you need or consult with someone experienced in electronics.