That method works well, and Doug uses it effectively in his article. It's also a great way to show someone else why you think there is an issue with an aimer, especially with "side by side" photos next to a good aimer.

There are three good alternatives, though:

(1) Buy a mirror with a reputable brand.
(2) Test for retroreflectivity with a flashlight
(3) Buy it, try using it in the sun and return it if it is defective.

In more detail:

(1) Buy a mirror with a reputable brand.

The glass mirrors with mesh aimers that are branded:

• Coghlans
• S.I. Howard Glass
• Vector 1
• Rescue Reflectors

should work - I have at least three from each source, and no complaints.

Glass mirrors with apparent mesh aimers that aren't one of the above, I'd test.


Doug's article lists distributors from whom he has received glass signal mirrors with dysfunctional mesh aimers, and lists what he finds to be "readily identifiable marks" of the fake mirrors.

I've only ever had one plastic signal mirror whose mesh didn't seem retroreflective (and it was the brand Doug mentions in his article), so it's much less of a problem for plastic mirrors. Decent plastic mirrors with retroreflective mesh/meshlike aimers are:

• The 2"x3" Rescue Flash mirror from American Medical Kits
• The various sized mirrors from Rescue Reflectors
• The "Sight-Grid" buoyant signal mirror from Coghlan's / Vector 1
• The 3"x5" ACR "Hot Shot" mirror
• The "Bright Spot" Scubapro Diver's Mirror from ASTI

Note that there are are also several good signal mirrors with decent solid retroreflective aimers - the StarFlash buoyant mirrors, in particular.

(2) Test for retroreflectivity with a flashlight

This is a handy way to test bubble-packed mirrors for those (like me) with a small "everyday carry" flashlight on their key chain. Hold the flashlight tight against your temple (right next to one eye) and hold the package with the mirror aimer about 9 inches in front of your nose, with the mesh illuminated by the flashlight. The mesh should look significantly brighter to the eye adjacent to the flashlight than the other. The difference is striking on most modern mirrors with retroreflective aimers, but much more subtle on pre-1980 Mil-M-18371 government issue mirrors, especially if there is a light background (e.g., white paper) behind them. With a black background, though, even such mirrors exhibit this clearly. If you are at home (e.g., the mirror came mail-order), this test works even better in darkness.

The camera flash method does work well for the pre-1980 mirrors - the top photo below of a 1968 MIL-M-18371 mirror was apparently take with flash,
and the lower one without:
http://www.modernforces.com/uniform_mirror.htm


(3) Buy it, try using it in the sun and return it if it is defective.

I've bought mirrors from many sources where the mesh didn't exhibit retroreflectivity, and I've never had any difficulty returning them.