In article ,
John Rouse writes:
Lime plastering should be cheaper, the materials are cheaper, and any
that falls to the floor can be re-used, unlike gypsum (as long as the
floor is clean), so there is less wastage. As the plaster can be worked
for longer, its easier to apply, the only downside is that it takes
longer to set.

In my experience, the cost of the materials (for gypsum plastering)
is quite insignificant compared to the labour cost (like about 1/10th).

Lime plastering is quite different to gypsum plastering - for one thing
you're not working against the clock so much.

No one's mentioned the horse hair yet...

--
Andrew Gabriel