Unitrade 715 Tagging Memory Test ?

Nowdays the tagging on all of the plates I have seen numbered 1 and 2 on the 14 cent parliament stamp number 715 appear very yellow while that on plates 3 and 4 is virtually colourless. It is obvious that there was a change in the composition of the tagging ink between the printing of these plates BUT was that difference obvious when the stamps were first issued 35 years ago.

I was not collecting Canadian stamps then so have no first hand memory of this but I woud be surprised if plates 1 & 2 appeared then as they do now.

Does anyone remember that far back of has any thoughts on the subject.

AQ

There definitely was a big difference when the were issued, as I have them marked as such in my album, which was made over twenty years ago. All plates were printed by CBNC. In addition, the 12c value has invisible tagging on the plate 1 of the BABNC printing, while plate 1 and 2 of the CBNC printing have the yellow tagging.

Thanks very much for that. It is not the answer I expected as I had assumed that when issued the tagging would have been more or less invisible. You live and learn !!

AQ