Breadcrumbs
You are here:
Identifying Green/Blue/Violet Phosphor Colours on Queen Elizabeth II Wilding Definitives
Some of the coloured phosphors can be sorted by normal sight without the use of
ultra violet lamps, as follows:
- Phosphor Graphite issues all have Green Phosphor.
- Phosphor issues from the 5d., 7d., 8d., 9d., 10d., 1s. and 1/6 values are all violet
phosphor, with 9.5mm. bands.
- 4mm. Centre Band issues of the 3d., value are all Violet Phosphor.
- Side Band issues of the 2½d. value are all Blue Phosphor.
- Most 9.5mm. bands are Violet Phosphor. The very few exceptions are from sideways
watermark booklet panes of four - reported on the Blue Phosphor ½d. value in particular
- and attract high prices because of their scarcity.
Thus all the above groups can be sorted without the use of an ultra violet lamp.
Having sorted these they can be used as 'standards' against which to compare other
issues when learning the subject.
Having identified the issues that can only come from one of the three colours of
phosphor issues, the remaining stamps are then more precisely identified by the
use of a
short wave ultra violet lamp.
It is important to exclude daylight or artificial light, as the stamps are best
examined for the phosphor colours using the u/v lamp in total darkness.
When applying the u/v lamp in close proximity to the stamps, keeping the lamp lit,
the phosphor bands will normally be visible as the bright stripes down the stamp,
in the normal two band, side band or centre band positions. The brightest reaction
comes from the blue phosphor, or from the violet phosphor; green phosphor is also
quite bright but a little less so than the other colours.
The most obvious difference between the three colours of phosphor occurs immediately
after the lamplight is switched off, whereupon the so-called 'after-glow' of the
phosphor remains visible for a short time:
- GREEN PHOSPHOR glows longest, somewhat less brightly than while the lamp is still
lit, but importantly the 'after-glow' is clearly green.
- BLUE PHOSPHOR glows almost as long as the Green Phosphor, and is clearly not green,
but rather of a bluish tone of greater brightness.
- VIOLET PHOSPHOR shows an after-glow in most cases, but is much shorter than the
other two phosphor colours, and indeed in some issues the violet phosphor after-glow
dies so quickly after the lamp light is switched off that you almost miss the after-glow
altogether. Any after-glow that clearly dies quickly, or instantly, is violet phosphor.
Violet phosphor is not clearly 'violet', but rather a short-lived bright glow, clearly
not green, but which could be said to be vaguely bluish just as well as violet.