Lot 7 Great Britain SC#721, 1974 UPU Issue, 2 VFNH Examples Of The 5p, Screened Phosphor & Silver Head With Normal For Comparison. Estimation $20, Click on Listing to See ALL Pictures

2 VFNH examples of the 5p multicolored from the 1974 UPU issue. One stamp shows clear screening of the "All Over Phosphor", which results in an almost silver head, with a regular stamp with a gold head for comparison. More details are written on the back of the 102 card. This is the first such variety of this nature that I have encountered.
Estimation for this variety is $20.

Although not listed specifically in either Gibbons or Scott, the commemorative and definitive stamps issued after 1971 can be found on a variety of different papers, which give differing reactions under long-wave ultraviolet light. Most all of the papers are chalk-surfaced, and until the mid 1990's the chalk coating fluoresces either hibrite (HB) or high fluorescent under the lamp. From the mid 1990's onward the coating gives a dull to dead reaction under UV. On the back the reaction can vary from dull to hibrite and also with fluorescent fibres in the paper. These varieties follow a definite progression as time moves on, with certain varieties only being found on certain issues. These lots do indicate though that there may be as many as five or six different varieties of paper on many issues.
The PVA gum found on these issues also varies. The paper used from 1971 until early 1974, called "original coated paper" had used a creamy white PVA that has a semi-gloss sheen and a streakiness similar to what you would see if you painted a wall using a less than full roller. Starting in 1974, dextrine was added to the gum, giving it a greenish tinge. This gum was dull at first and later became a semi-gloss gum. Eventually by 1976 the colour changes back to white and in the mid-80's it goes back to being greenish. Finally, by the early 2000's it becomes a glossier white.