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Monday, March 19, 2012

Survival Kit: Signal Mirror

Original Article

A signal mirror is one of the many things that you could choose to add to your survival kit. It is a tool that could save your life. A signal mirror is, you guessed it, a mirror – but it’s design and purpose is to alert others of your location.

An ordinary reflective mirror is better than nothing, and will work if handled properly. The thing is, it will not be as effective as a mirror designed to be a ‘signal mirror’ which includes features that help you to aim the mirror precisely at the target (an aircraft, ship, vehicle, spotter, etc.).

The secret to a true signal mirror is something called retro-reflecting material, or a retro-reflective mesh style ‘aimer’.

“Retro-reflective” means that the light is reflected back to the source. In the context of a signal mirror aiming device (the round hole and mesh in the middle), this material consists of tiny glass beads glued to a mesh screen, which creates a fireball on the mesh (an image of the sun), which is used to indicate where to point the mirror. You tilt the mirror to overlay the fireball on your target.


The original patent for the signal mirror (# 2,557,108) was issued in 1951 to inventor, Richard Hunter.

A few key notes from the Mil-Spec…
Military Specification MIL-M-18371D(ASG), Mirrors, Emergency Signaling
  • 2 different types of signal mirror, a 2×3″ and a 3×5″
  • 2 layers of glass laminated together with a sighting device and lanyard
  • Wide angle retro reflecting material for sighting

Signal Mirror Aiming Instructions:
  • Reflect sunlight from mirror onto a nearby surface, hand, etc.
  • Slowly bring mirror up to eye level and look through sighting hole. You will see a bright light spot. This is the aim indicator.
  • Hold the mirror close to the eye and slowly turn and manipulate it so that the bright light spot is on the target.
  • Even though no aircraft or ships are in sight, continue sweeping the horizon, for mirror flashes may be seen for many miles, even in hazy weather.
Note: Never look directly at the sun, that includes through the aiming hole!

Not every signal mirror is made from glass. In fact most are made with plastics and other reflective coated materials for lighter weight and cost. However, the signal flash produced from a glass mirror cannot be beat. Here’s one that I found online:
Military Glass Signal Mirror

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