Friday, 29 August 2008
ATN Sheets and Marginal Markings - Part 2
Always glad to oblige.
Here's a block showing the marginal markings that Roy mentioned below.
Opposite row 18 (the top row of this block which is the 18th row down from the top of the pane) is the phosphor control mark. I show it here in light blue, but of course on the real stamps it is only visible under ultraviolet light.
Opposite row 19 is the colour control mark, and below that are the colour dabs.
A quick trip to a couple of reference works didn't turn up any information on these markings. I believe they are used to insure that the positioning of the paper is correct and the the inks (colour and phosphor) are being applied correctly.
I'm going to see if I can find out a little more about them. If so, I'll update this entry.
I would add one other thing to Roy's comments. Cylinder blocks, such as the 46p block of six that Roy shows, are almost always collected with an angled side margin and have been for the last couple of decades. Angled lower margins are less common, especially with stamps like these where the margin is perforated through. I believe collectors would find that recent cylinder blocks with straight side margin would be worth less than blocks with the angled margins.
Tallents House (the British Philatelic Bureau) sells cylinder blocks with straight margins.