In 1941 the navy was researching new compounds for dye markers that used no critical materials the dye in service at that time used aluminum powder.The adopted fluorescein for thier dye under spec. M528 and under this spec. it recommended research into a packet that could attached to the life vest later adopted under spec. M-566 in nov. 1942 disrtubuted in nov. 1942 along with TO 77-42.When the dye is distributed in water it leaves a yellowish green color creating a 25ft diameter field that can be seen for miles on a clear day and last up to 1-3 hours depending on currents.The packets are made of two parts an oter waterproof vinylite coated fabric and an inner puorus bag with dye.The marker when opened looks like a giant tea bag.The edges are either sewn or cemented.The early M-566 packet had a 24" cotton tape on the outside to tie to vest with a tab on bottom to pull and release die.A later amendment M-566A changed the design of the outer packet witht he pull tab on top and allows a better grip to pull down instead of to the side which is easier to open again a later amendment M-566B changed the construction and material types and looks very similar to the AAF dye marker.When these packets wer first ditributed only one per vest was issued and sometime in the middle of 1944 two were added as standard.
pictured are the M-566, M-566A and M-566B from left to right.
These packets are still in use today and are very highly effective in search and rescue only the technology in materials have changed such as nylon in place of cotton tie tapes which is the major distiguishing feature between WWII and post war packets
Edited by dustin, 16 February 2007 - 09:26 PM.