[droopyEyelids]

One of the first things that this PDF talks about is the application of limewash to different substrates, and how different substrates must be prepared differently.

It sounds like the kind of thing a lot of tradespeople would screw up- like it requires study to do properly. They specifically call out how mortars and renders (which includes stucco) should be composed with the 'mechanical keying' of limewash in mind.

[rabf]

Most important preparation in my experience is to mist the substrate before application to prevent rapid drying.