Stumpkiller said:
As far as I can tell the screening of granulations did not catch on until 1825. That's when the current "F" designations stared to be used in Europe.
Or maybe 100 years earlier?
THE SOUTH CAROLINA GAZETTE
September 25, 1736
Charleston, South Carolina
JUST imported in the King George, Jacob Ayres from London, white and colour'd plains, strip'd duffils, bullets, shot, F FF FFF gunpowder, Saxe Gotha hoop-petticoats,
THE SOUTH CAROLINA GAZETTE
June 11, 1741
Loaf Sugar, Gun Powder in half Barrels FF and FFF, Bullets, Strouds, Indian Trading Guns, Mens and Boys Felt Hats
The Pennsylvania Gazette
January 7, 1752
Imported (chiefly) in the Myrtilla, the last ship from London,
....best London steel, shot, F, FF, and FFF gunpowder....
Spence