Thanks for looking. I caved and ordered a hardcopy from Amazon - they say I'll get it tomorrow.
I'll also email the USCG contact to see if they can point me to a copy of the current USCG signal mirror spec - all they say is:
All lifeboats and inflatable liferafts are required to carry a signaling mirror approved by the Coast Guard under approval series 160.020, using the “USCG Specification for Signaling Mirrors for Merchant Vessels” issued in October 1944.
They used have a summary of their spec on their website, at
https://www.uscg.mil/hq/cg5/cg5214/survivalequip.asp#160.020But it is not there now, nor can I find it by searching. Fortunately, I grabbed it at the time - this is what it said:
EMERGENCY SIGNAL MIRROR
APPROVAL CATEGORY: 160.020
APPROVAL GUIDANCE & INFORMATION: Mirrors for signaling must be flat enough and have a surface of sufficient reflectivity to meet detailed tests in paragraph (D). They must be durable enough to retain this flatness and reflective surface during use or after being subjected to salt air or salt water in combination with heat or cold and sunlight.
A. MATERIAL. The main base material shall be either metal, plate glass, or "A" quality window glass. All mirrors shall present a smooth, even, and unpitted reflecting surface, even after the salt spray test. Metal mirrors having a base of corrodible metal shall be plated over the base with copper and upon that a plating of nickel with a final coating of chromium. No plating shall be done until the final stamping, cutting and grinding is completed. The reflecting area of glass mirrors shall be either aluminum or silver deposited on glass. The rear of the reflecting area and edges shall be adequately protected from corrosion by a durable protective coating. If non-tempered glass is used, the glass shall be securely protected from breakage by means of a cushioning frame. A woven twine lanyard shall be securely attached to each mirror by means of a hole provided for it. It shall be approximately 36" long and in the form of an 18" loop. The lanyard material must be able to withstand a pull of 50 pounds when dry. A wiping cloth, that will remove finger and hand stains, of twice the area of one mirror shall be included with the mirrors.
B. DIMENSIONS AND SLOPE. The mirror shall have a reflecting area of at least 17 square inches and shall be rectangular in shape with rounded corners. The mirror shall be flat except as noted below, and shall be of such thickness that it cannot be easily deformed in use. At the center of the face of the mirror, there shall be a sighting means of one of the following four types:
1. Metal Mirror Type. This type mirror should be made of metal as specified in paragraph A. There shall be a round sighting hole in the center of each metal mirror 3/16" in diameter. A concentric depression about the hole of about 1/2" diameter and approximately 1/32" deep may be formed, if desired. If depressed, the side of the mirror in which the depression is made shall be identified by some permanent marking on the mirror, such as "Toward Face". This mirror shall have a central mirror area on the back at least 1-1/2" in diameter concentric with the sighting hole. This back mirror shall be parallel to the front mirror within 15 minutes of angle. It shall be of sufficient quality to enable a person of normal vision to read newsprint-size lettering with the mirror 4 inches from his eye and the lettering 8 inches from the mirror.
2. Cross-in-Glass Type. This type mirror should be made of glass as specified in paragraph A. At the center of the face of the mirror there shall be a sighting area in the form of a cross. This area, on which no metal shall be deposited, shall consist of two lines 3/64" x 1/2" to 1", mutually bisecting at right angles. The optical quality of the sighting area shall be such that a person of normal vision can see a distant small target through it when using the mirror in heliography. This mirror shall have a central mirror area on the back at least 1-1/2" in diameter concentric with the sighting area. This back mirror shall bo parallel to the front mirror within 15 minutes of angle. It shall be of sufficient quality to enable a person of normal vision to read newsprint-size lettering with the mirror 4 inches from his eye and lettering 8 inches from the mirror.
3. Reflex Type. This type mirror should be made of glass as specified in paragraph A. The sighting hole shall be a clear window at least 3/4" square of such optical quality that a person of normal vision can see a distant small target through it when using the mirror in heliography. Behind the sighting hole a retro-directive reflector button roughly 5/8" x 1" in size shall be mounted to make contact with the clear window along one edge. This button shall be tilted at about 30° from the plane of the mirror so that there shall be a crack between the button and the window 3/4" long and roughly 5/8" wide through which one can observe the signaling target. The red image of the sun formed by the button shall not be more than 2* in diameter from any part of the effective area of the button for any direction of incidence loss than 25º from the normal to the face of the button. The seal protecting the rear reflecting surface of the button shall remain watertight when immersed in six inches of salt water after the button has been warmed to 140ºF. and chilled to -40ºF. for four successive cycles.
4. Blister Type. This type of mirror shall be made of glass as specified in paragraph A. In the reflecting area, there shall be a window of approximately 1" diameter. The window shall be covered with a blister securely attached to the back of the mirror. The inside wall of the blister shall be covered, except at the center where a clear space of approximately 1/4" diameter is to be left for use as a viewing hole, with a retrodirective material. This material shall be of such quality that when sunlight strikes the front of the mirror, at any angle less than 65 degrees from the perpendicular, a red or orange colored image of the sun can be seen by a person looking through the viewing hole in the direction that the mirror is aimed. The red or orange colored image shall not appear to be more than 2 degrees in diameter. This red or orange image shall be readily visible against the sky as a background, even after the mirror has been subjected to the salt spray test of paragraph
C. PACKAGING. A pair of the mirrors together with their lanyards and instructions for use shall be inclosed in a single durable watertight container inclosed in an outer durable container. The outside of the outer container shall be plainly marked SIGNALING MIRRORS and also bear the name of the manufacturer.
D. TESTS. Any of the mirrors submitted as samples or any furnished to ships may be subjected to tests to determine their suitability for the purpose intended. The Coast Guard does not test materials or systems for approval but rather specifies the required test methods and minimum performance criteria for approval. Product testing must be performed by a Coast Guard Accepted Independent Laboratory. Among these tests are the following:
1. Salt spray. The mirror shall be thoroughly cleaned, suspended about 15º from the perpendicular and subjected to a spray of 20% by weight of reagent grade sodium chloride at about 95°F. for 48 hours; then wipe the mirror using only the wiping cloth furnished.
2. Drop test. The mirror shall be dropped three times from a height of 4 feet onto a hardwood base securely bolted to a concrete floor. The glass mirror shall not chip, crack or break, and the metal mirror shall not permanently deform, nor shall any plating chip or peel from the metal base.
3. Reflectivity. The reflecting surfaces of the mirror shall have a 45° luminous specular reflectance of at least 0.60 for light of about 2850°K color temperature, even after the salt spray test.
4. Flatness. The average deviation of the light beams reflected from all the mirror shall not be greater than 0.8 degrees from the direction of reflection by a perfectly flat mirror.
5. Watertightness. The watertight container shall show no leakage after being immersed under a one foot head of water for two hours.
E. INSTRUCTIONS. Two copies of instructions and diagrams illustrating the use of the mirrors shall be enclosed inside the waterproof mirror container. The instructions and diagrams may be on the back of each mirror if permanently affixed. Otherwise they shall be printed with letters at least 1/8" high on water repellent paper.
SUBMITTAL PACKAGE: Please submit the following information in the Submittal Package:
A cover letter requesting Coast Guard Type Approval of the equipment.
Two mirror samples each in a watertight container.
Required information and test report from the Accepted Independent Laboratory.
Two copies of the instructions and diagrams illustrating the use of the mirrors.
Please send the Submittal Package and other related information to the following address:
Commandant (CG-ENG-4)
U.S. Coast Guard Stop 7509
2703 Martin Luther King Ave Jr SE
Washington, DC 20593-7509
Once the equipment has been approved by this office, it will receive Coast Guard Type Approval and a Certificate of Approval (COA). The COA will be issued for 5 years and will remain valid during that time period if product meets the testing of the Quality Control Program.
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