Looking for the Wndsn store? This way, please: Limited editions tools and embroidered morale patches from the Wndsn Expedition Team.


One field of our ongoing research is illumination, specifically passive, and emergency light solutions.

GITD vs Chemlight vs Tritium

Mini-chemlight, GITD tab, or tritium vial; which one and when? Depending on the application, all three have advantages and disadvantages.

Wndsn: GITD vs Chemlight vs Tritium

Brightness over time

Given comparable form factors:

  • First 10 minutes after exposure: Mini-chemlight = GITD > Tritium
  • Beyond 10-15 minutes after exposure: Mini-chemlight > Tritium > GITD
  • Beyond 4-6 hours after activation: Tritium >= Mini-chemlight >= GITD

For rapid changes from light to dark GITD is brighter than mini-chemlights and Tritium, for practically infinite marking in continuous low-light settings, Tritium is superior; and for fast and acute ambient illumination, chemlight is preferable.


10 years > 4 hours > 10 minutes. 

  • GITD: 10 usable minutes, starting immediately after charging.
  • Mini-chemlight: 4-6 hours, starting at will.
  • Tritium: 10 years half-life, if it's on, it's on.

Supplies required

  • GITD: sunlight, UV-light, a 1000 lumen torch isn't enough.
  • Chemlight: consumables, the more the better.
  • Tritium: good as is.

Shielding and containment

  • GITD: no shielding needed, contain light in mylar pouches, etc.
  • Chemlight: prevent breaking prematurely or destruction by keeping within solid plastic tubes, etc.; contain light in mylar pouches, etc.
  • Tritium: prevent vials from breaking by using the obligatory cage-shaped holders, contain light in mylar pouches, etc. (Tritium emits enough light to shine through 500d Cordura)

As always, more area equals more light. Area makes a big difference, since everything about light is quadratic.[1] If you need more light, bring a bigger or more light sources, no matter which of the above.

See also:


  1. Wndsn: Measuring Light