The local lime is from Chemical Lime co - they are all over Canada and the U.S. It costs about $10 a bag! The company has a tech support lady who seems to know about fresco.

The problem with plastering over drywall is twofold - the weight can be too much and the walls are never flat. A plastered wall - using plumb bobs, screeds, and a darby is as flat as a billiard table and as shiny as a slab of granite. A proper polished plaster finish looks like polished stone - but is about 1/2 the price (25 cents a sq ft.)

Architectural lime finishes was combine three trades - lathing, plastering and painter. It is actually the lathers who are hard to find these days.

For pigments - kremer-pigmente.com - NY office.