U.S. Air Force’s official survival handbook describes the signal mirror as “probably the most underrated signaling device found in the survival kit.”

Signal mirrorWhether you need a mirror for Ten Essentials Kit or you just want to be sure you look sporty on the trail, a signal mirror is a handy trail aid and it is easy to make. I got my first mirror with an official BSA grooming kit, but it wasn’t long before it got too scratched up to use. So it became time to make one. 

Here are the simple steps needed to build a signal mirror:

Supplies

  • Two pieces of glass mirror (preferably 3 to 4 inches is ideal)
  • Super Glue
  • A straight–edge
  • A pencil with a good erasers
  • A sharp knife with a good point or a nail

Making a Signal Mirror

  1. Mirror suppliesUsing the straightedge and pencil, draw an X, corner to corner on each mirror
  2. A the center of the X on both mirrors, scrape off a 1⁄8-inch-diameter circle of the paint with the point of the knifeMaking a singal Mirror
  3. Make sure that the holes are in the same place so that when you glue them together, they match.
  4. Clean up the holes using a pencil eraser.  There will still be some glossy stuff on the glass that comes off best with an eraser and some elbow grease.  Make the edges clean because this is your “aimer.”
  5. Next, glue the two mirrors together, making sure to match the holes on the back to see through. Keep glue away from the hole.

Using the signal mirror

Method 1

  1. Mirror aimingUse the mirror to reflect sunlight onto a nearby surface like a raft or your hand.
  2. Slowly bring the mirror up to your eye, while making sure that the reflective surface is not obscured by your fingers or a hat.
  3. Tilt the mirror up toward the sun (not directly into it, though), until you see a small bead of light in the back mirror. This will be on your cheek or clothing.
  4. Once you’ve found the bead of light, move it toward your intended target. Keep the bead of light in view as you do this.

Method 2

Using a mirrotTo aim it, hold the mirror with one hand and extend the other hand in front of you. Tilt the mirror until its reflected light fills your empty palm. Make a V with your illuminated fingers, then sight through the V toward an aircraft.

If your mirror has a mesh material in the mirror’s central hole, this is a retroreflector; it reflects light through the hole at an angle that is supplementary to the sun’s angle of reflection on the mirror. Looking through the aiming hole, shine the mirror on a nearby object, like your hand, and find the bright dot on the retroreflective material in the aiming hole. Then move the dot to the distant object you want to signal.

 

Make a Giant Fold-up Signal Mirror


team mirror schematic
Gian MirrorA 2–by–2 foot square mirror would be bulky, but you can make this huge mirror  that fits into a backpack with these instructions. Use standard 1–by–1 foot decorative mirrors (approximately $2 each at a discount store).

Giant Fold up mirrorCut a 1–by–1 square foot piece of 1/2–inch plywood (if it’s thinner, it may warp). Drill five holes: one in the center, the others 1½–inches from each corner. These are to accommodate the little “jiggers” (hammer–in permanent nuts, as shown). Use ¼–inch coarse threaded jigger with a wing bolt and a 1½–inch washer plus a homemade rubber washer from an inner tube. Buy an extra jigger and put it near the center (but offset) and on the other side of the plywood.

You’ll find it will hook up perfectly to a standard camera tripod, which will let you, hold the signal on someone you know is there…until they notice you.

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Darryl Alder

Darryl is a retired career Scouter with more than 30 years of service. However, his pride in Scouting, is his volunteer service as an Associate Advisor, Varsity Scout Coach, Scoutmaster, Cubmaster, Chartered Organization Representative and Commissioner.

2 comments

  1. Joyce Olesen says:

    Hi Darryl,
    Wanted tell you a story about mirrors. When my husband and I lived in Springville, he hiked up Mt. Timp every year. As he got older I would wait out by the mall in Orem and he would signal me with a mirror when he got to the top safely. I could then relax and go home. He hit the sun just right, but even though we thought I was in the right place, I could not work it right so he could see me. It was fun though. I am going to try to make one like you describe. Thanks.
    Joyce

  2. The three basic ways of aiming a signal mirror are:
    (1) retroreflective aimer
    (2) double-sided (“rearsight”) aimer, and
    (3) foresight aimer.

    In more detail:

    (1) Retroreflective aimer.

    This type creates a glowing ball of light, visible only when looking through the aimer, in the direction of the beam, like a “Red Dot” gunsight. The video at the top of this page shows you how to make that type, as do the videos and text here: http://www.bsaontarget.org/mirrors (that link also reveals how the retroreflective material in the aimer creates the glowing ball). Commercial mirrors of this type usually produce a white dot, and often use retroreflective mesh. Examples are the MIL-M-19371E USAF issue signal mirrors, the 2″x3″ polycarbonate Rescue Flash mirrors sold at the official BSA online store, here: http://www.scoutstuff.org/rescue-flash.html, or the Coghlan’s 9902 2″x3″ glass Survival Signal Mirror, sold in many places. Retroreflective aimer signal mirrors are the type issued to the US Coast Guard, US Air Force pilots, and the French, Italian, and Chinese air force pilots as well. Here’s a video of two USAF Thunderbirds officers using retroreflective aimer signal mirrors: a “red-dot” at left, and “white dot” at right: https://youtu.be/Y3gjA4PpAY0

    (2) Double-sided mirror, or “rearsight” aimer.

    This is the type made above by gluing two mirrors together. It uses the beam of light that passes through the hole in the center to aim the mirror. A video version of the instructions above is here: https://www.youtube.com/watch?v=b4D3SzSZqoA , and instructions on how to use them from a USAF survival manual is here: https://flic.kr/p/dQ1dK9 Most of the signal mirrors issued to US forces in WW2 were of this type, using a cross-shaped hole rather than a round one. A WW2 instruction video for these is here: https://youtu.be/vmnRrCVBaP0

    (3) Foresight aiming – “method 2” above.

    In this method, we use something illuminated by the reflected beam as a sight. The “Vee-finger” version of this approach should be your last resort – it is very inaccurate The reason is – the beam is MUCH narrower than it seems on your fingers – try this method against a shadowed wall 100-300 ft away to see this (or check out the tiny spot in this photo: https://flic.kr/p/dQgCVq ). Using an object far away, as the lower diagram above, is more accurate, but often inconvenient.

    Accurate handheld versions of the foresight method use a central hole to look through (with a glass mirror, scratch a small sighting hole in the silvering, as for the double-sided aimer above), and something to catch the “shadow spot” cast by the hole as the foresight. Because the “shadow spot” is small (closer to the size of the beam you are trying to aim), it is far more accurate than the “Vee-finger”. A video of such a commercial mirror in action is here (preceded by a 15 second ad, alas): https://youtu.be/Uf-eykGL4VM and photo of a British air force model from WW2 is here: https://commons.wikimedia.org/wiki/File:Signal_Mirror_British_Dinghy_Heliograph_4inch_1943.jpg .

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