What a Machin lover always wanted to ask DEEGAM but never ..

[Rein]

What this "crater" paper has in common is that the front surface is cracked!

As the wire side of a paper usually has the imprint of the wire and the "missing fibers", we can easily state that in this case the wire side of the paper had been coated!!! What we see at the back is the felt side of the paper!

Douglas Myall at some places refers to an "experimental coating" without explaining what is meant....

to be continued ...

The missing fibers at the front had an impact on the printing itself! Although, the coating may have disguised it a bit!






incidentally you can see the "direction of printing" (see "FRE") which is a much wider phenomenon that Myall let us believe...



to be continued ...

[Rein]

In David Elfman's study we find

David Elfman "Queen Elizabeth II Definitives of Great Britain" The Wilding series of British stamps

http://employee.lasierra.edu/~wclarke/rsc/WILDING.pdf

and in it:



Is the mirrored paper wire [at the right] the characteristic of the whiter paper or did we have this before??

The blue lines are mine...

The un-mirrored paper wire - steeper lines from top left to bottom right - was the type we see introduced for the 1967 commemoratives on coated paper without watermark and surely must have been used for the pre-decimal Machins.

to be continued ...

P.S.

What helps you to see the lesser steep diagonal lines is step aside - watching the left hand stamp moving to the right and vice versa