Hi there everyone, thank you very much for all the replies. This is getting interesting (and confusing).
The Linn's article called it "serrated perforations
". An online search of a MEPSI certificate of a similar stamp also gave "serrate perfs
The exhibit in the Cherrystone link just called it "serrates
", made with a mysterious mechanical device.
Yet, Spink described it as "serrate roulette
", though such a roulette cannot be found in the references that rod222
provided (Archer roulette perhaps?). I did find a definition of a "serrate roulette
" here --> https://brixtonchrome.com/pages/phi...with-g-to-z,
which says that 'A serrate roulette is a roulette in which the cuts to the paper are rounded', though I struggled to see the rounded areas on the image of the stamp that I posted - the spikes on the stamp are all 'pointy' (NB: I do not own the stamp).
And then, there is the very similar-looking embossed paper seal posted by John Becker
- all pointy spikes too, though the spikes are longer, and the cutting much more well-defined - not sure if this means an entirely different production method (die-cutting as suggested by Parcelpostguy
?) is used in this caee.
Sure a lot to figure out and learn here!