Hi Gary,
I do not know much about Gypsum being used on building in Paris.
Is that why it is called Paris plaster?
In the country side I am sure lime was widely used.
I do not know that anything has been written on this subject.
May be l' Ecole d'Avignon would tell us more.
I could do some research if you are interested.
I found in France a really big natural hair brush that I use for limewashes.
It can be clipped sideways on top of the bucket for dripping.
It is a very good one but I am pretty sure I have seen the equivalent in catalogs.
Myriam