Ok! I remember now... This was explained/debated in the other topic somewhere. (besides the one you mentioned)

But here it goes again:

Dolomitic lime results in a lot of magnesium in the putty. And it is so - it smells tastes and feels slightly different, so it is not just "molecular" difference. Magnesium makes plaster to be more "plastic", but that is a choice for people who know little. Also magnesium plasters preferred for commercial plaster/stucco applications where speed is the issue, or for uncolored ornamental plasterwork.

For color magnesium is not a friend gives fluorescence spots, poor adhesion of the color layer, etc. Also magnesium has longer hydrating time. Any lime stone will produce some magnesium (high calcium lime contains upto 7% of magnesium - dolomitic has over 30%)

In the past burning of the limestone has little control over the temperature throughout the load therefore resulting quicklime was impure. Aging the lime for 10+ years in the pit was needed to properly hydrate every bit of it. Modern technologies produce more consistent burning therefor 2-4 years in the pit is sufficient.

I am not at liberty to say - professional secret, you know... (just joking).

Anyway, i am not an expert in colored plasters and my explanation applies to fresco painting where the color layer creates or can be compared with calcium saturated, bounded surface crust. When pigment is mixed into the plaster itself poor adhesion is not an issue, however you may still have fluorescence.

About frustrating - you are correct that is not exactly the word. More likely "philosophical" in the matter of: when and will I be able to keep up with postings. The site is alive and growing fast.
Have you checked our Fresco Workshop Program at
http://frescoschool.com ?
we already have international students.

we are also rearanging content into Channels to be more accessable, check Fresco Channel at:

http://www.truefresco.com/channel_fresco.html

perhaps the fact that our site is so easy to find - top ten in every search engine for any fresco related search as well as it's size make people feel that the discussion is "too public" - you do not see rock concert crowds in the public library, but there are millions of libraries and only one "fresco library" - TrueFresco.com - we are pritty much it or strive to be... So the crowds will be here - our stats: 1996 - 2000 page views per month and in 2002 - 200,000 page view per month. So people are "snooping around" we just have to make them talk. Interested to help?
Scagliola topic is wide open...