As I tried to bring some kind of order to my collection of Belgian stamps I stumbled upon a paper variant I have not encounter before, polyvalent paper. How can you tell the difference between ordinary and the polyvalent ones? Any help would be greatly appreciated.
Description: Polyvalent paper shines white to blue-white in UV light (variant on normal paper shines greenish) Issued in sheets of 60 or 120 stamps and in roles of 1000 stamps. Every fifth role stamp has a number backside.
Stanley D. Brown
APS member # 139241 Sacramento Philatelic Society # 2144 Great Britain Philatelic Society # 1526 Belgian Philatelic Study Circle