Highlighted markings on wooden propellers

[pmdec]

Hello !

I have a technical issue concerning the marking of wooden propellers for the period 1908-1918 :
I have two propellers that have highlighted markings, and the same numbers in "classical" markings (hollow) . The highlighting is wood, exactly as if the wood has been carved around the figures and letters.

The two propellers are about 1915 and have the SFA "stamps" (army certification) :
- the first is probably a Regy for a Voisin 5 with a Canton Unné 150HP (serial 300, serial number 3(?)169),
- the second is a Ratier for a Morane Saulnier with a 50HP Anzani (serial 15, serial number 19)

Each photo has been dupicated with the the hollow markings in blue and the relief markings in red :







My question is : I wonder how have been achieved the highlighted marking !

Thanking you in advance for any information you may have about this technique, and sorry for my poor english,

PM Decombeix

[Dave]

Very interesting, and I don't know how or why it was done that way. I will be very interested to see if someone has an answer.

Besides being difficult to do, I think the embossed method would be more "fragile" in use, and could easily be worn off and made to be unreadable.