My understanding is that anti flash gear was introduced late in 1917. It was certainly in use by September 1918. I suspect the photograph showing the ratings in anti flash gear was taken in the later stages of the war. On the other hand I have read accounts that some experimentation took place on the battle cruiser Queen Mary in early 1916 - lined variations on the design of gas masks then being issued to the troops. Did not do her crew much good at Jutland...