thanks for that thorough answer.
I had cracks too,very superficial ones, when the quantity of lime was too important compared to the quantity of sand.
My frescoes are too young for me to be able to say if it is resistant or not. I did one outside, on the wall of an old house,more or less exposed to the weather, it "holds" to the wall perfectly so far.
I do 3 layers after the gobetis, in the putty for my first and second rough layer I add brick thinly crushed, I let the whole thing sit for a 2-3 weeks.
The mortar is very "workable" and so far has been proven solid enough.
I'll definitely try Italian putty next time I go back to Europe.
I've also heard of "pouzzolane" these volcanic ashes that the italians added to the lime to re-enforce it's strengh. I would like to try that too, not for frescoes, but for simple mortars.
What kind of sample will you get from Mr Curtis?
The CAOH2 or the dolomite?
I am about to use the CAOH2, I really would like to have feed back from you if you come to use it.
Thank you for that helpfull correspondance.
Mathieu.