Good discussions, and thanks for sharing with everyone
I am sure that the european, italian , swiss wall mixtures would vary with each culture, and of course the ingredients that was available in each region. Correct me if I am wrong but I believe that the Italian, or Mediterranean culture had many centuries of experimentation and came up with formulas that even today cannot be improved upon, providing that we knew what they used.
The only thing that I am sure of is that in Upper Canada only good sharp sand along with the lime was used in the preparation of the wall surface's 2 underlayers, and if possible hair from cattle or horses was used as a binding agent.
I have read some accounts where the mortar used in the ancient Roman walls in Britain have been examined to determine just what they used at that time, Ken might have something to add on this front, I suspect that they also used ingredients that was available locally rather than import.