Walsall phosphor and fluorescence variations, continued.

I've reported at length (most recently here) on the phosphor and fluorescence variations on counter sheets printed by ISP Walsall, and similar variations on booklets have also been noted, some going back many years.

It comes as no surprise that the same sort of variations occur on Walsall-printed business sheet stamps.  These are much more difficult to find because they require the purchase of whole sheets (of 100 small stamps or 50 large letter): if the stamps turn out to be the same then that expenditure - by collector or dealer - is wasted as few people have an outlet for that many spare stamps.

I've recently been shown examples of the small stamp sheets from 2018 and can now show variations between two printings of each value.

2nd class - printed 14/03/18 and 23/04/18.  Phosphor is blue, but on the later date the iridescent ink has yellow fluorescence.

1st class - printed 01/03/18 and 17/04/18.  As above, the phosphor is blue, and the iridescent ink has yellow fluorescence.

These will be listed in the next edition of our Machin Checklist, but we will not be able to supply them.  For the record, the ones we have already supplied are of the first type, with blue phosphor only.

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