Practically
all definitive stamps have for 40 years had some form of phosphor
coating applied over their surface. This enables sorting machines
to distinguish first class post by detection of the bands' reaction
to ultra-violet light. The most common types of application are
bands, running vertically down the stamp or some form of coating
over the whole stamp area.
It
is quite easy to detect whether a mint stamp has bands or
not - the phosphor shows as a matt area on the surface when the
stamp is viewed at an angle. Distinguishing between stamps
which have either no coating, 'all over' phosphor, phosphor coated
paper and the later advanced coated paper is much more difficult
and really does require an ultra-violet lamp. Fortunately, most
issues will have other more clearly distinguishing features but
there are still several values, noticeably the 2p, which
can be found in virtually every conceivable type!
I
make no apologies for including variations PCP1 and PCP2
in several issues. This is because I had noticed some extremely
shiny items appearing in 1980 with often quite rich-looking
colour as a result. I kept examples of these together with their
duller counterparts and it wasn't until some time later that
I read about the different types of PCP that were being used on
some issues. I have, therefore, included all instances where
I understand that the shiny PCP2 was used as this produces a very
clearly identifiable separate stamp. Where only one type of PCP
was used I have left the reference as PCP without a number.
I
am somewhat troubled by having to include the blue phosphor
issues that started to appear in 1995. Apart from those with other
changes, I would probably have never noticed but the British
Philatelic Bureau made a huge marketing effort, launching the issues
with mailshots galore as if they were something quite remarkable!
Much as though I would love to have had checklists for some other
things and never did get them, they even sent out regular
updates listing what we should all have and when the next
ones would be appearing. It was all quite extraordinary but made
a pleasant change from the centre stage being virtually permanently
occupied by commemoratives and mugs. Accordingly the blue phosphor
issues simply have to be included - but you'll need a lamp
to detect some of them!
Something
I have yet to attend to is the business of bars. Whereas
most issues were produced with bands of phosphor running across
the whole sheet there have been many occasions when a first class
stamp has been printed adjacent to a second class stamp and
the process of running a band or two across a whole sheet
wouldn't work. This has applied principally in the production
of booklets featuring mixed panes of stamps. (This is also where
most of the left and right band variations come from.) In order
to ensure that the first class two bands didn't overlap onto the
second class single band someone had the bright idea of printing
phosphor in bars, each bar being somewhat shorter
than the height of the stamp to reduce the likelihood of overlap.
These are quite easy to spot of nice new clean booklet panes but
it can be quite a task to determine whether a band is really a bar
on used items and even some single mint stamps. Detection can be
further complicated by the fact that not all bands are as
clear as we would like them to be and there are inevitably going
to be examples where the phosphor drains off at one edge and
what should be a band looks like a bar. Luckily for us, practically
all instances of bars appear on stamps which feature
in the catalogue as a result of other criteria but I am conscious
of the fact that there must be a few which exist with identical
criteria apart from one variety having bands and another bars
and that these must be included. I just have to admit to not
having got round to that job to date.
If
anyone is desperate to know if they are missing something then I
am happy to advise on individual issues in the meantime.
A
similar argument applies to my omission of reference to the width
of bands or bars. They do come in a range of widths but unless you
are disposed to operate a magnifying glass, ruler and ultra-violet
lamp all at the same time, detection will be troublesome. Should
there be any items for which band width is, indeed, the sole distinction
then I suppose I shall have to include them - and will do,
when I get round to it.
Incidentally,
if there is anyone out there who has completed this bit of research
I would be glad to hear from you and will gladly include appreciative
comments, links or whatever is reasonably demanded.
What
you won't find in my lists are 'missing phosphors'. I accept
that they exist and many dealers list them and they do seem to command
high prices but they remain accidents in my opinion and, whilst
of interest maybe to some, in the same way that printing errors
can be collectable, they simply don't meet my criteria for this
catalogue. Looking at the number that exist, and the prices
demanded, I would feel obliged to include a link to providers
of second mortgages if I were ever to change that view. |