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 get my first mir­ror with an offi­cial BSA wash 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 full time professional Scouter for Utah National Parks Council, Boy Scouts of America, serving as Director of Strategic Initiatives. But his pride in Scouting is his 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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