Wimmer's composers

You don't need to look very hard to bump into essays of 'stamps' portraying various composers, engraved by the Austrian Georg Wimmer. They are usually dated 1955-6, to coincide with Mozart Year, and they are usually labelled as proper stamp essays.

But are they? They most certainly do not include the name of the country or a value, nor does the design cater for the future inclusion of either. I know that's not foolproof evidence, but to me they look more like private engravings, practice pieces maybe even, than proper stamp essays. Especially when they're so readily available and many are signed as well. They also come in a long row of other Wimmer 'essays' portaying either J. F. Kennedy or including scouting symbols. Again, we see engravings without the mention of any country's name or value.

So basically, I haven't a clue what these really are, and I would appreciate someone (anyone!) with authority to comment on them. Having said all that, they are great to collect because they come in many shapes and sizes. Most popular one is the sunken die proof, as shown above, on card. These are usually the signed ones.

Schubert die proof, state 1
But if you look a bit further you'll find various progressive die proofs as well. For the Schubert essay, for example, I have the finished product but also four sunken die proofs of the engraving in various states. They are beautiful examples of how the engraver works to build up his masterpieces. I believe for some composers there are even eight different progressive die proofs!

Schubert die proof, state 2
Then there are also colour proofs to be found. As far as I know, these are usually printed on paper, and cut to singles or pairs. The colours used are normally black, blue, brown, green and red.

The Kennedy essays, which I don't have so I can't show them yet, may also be found with perforations and on variously coloured papers. All in  all they may or may not be proper stamp essays, but they're great to collect and then show how engravings and subsequent proofs are made, thereby giving more insight in stamp production as well!