our visit to Ygrand last week here we learned about traditional ways of restoring walls of these old buildings using limewash. We have now done about a third of the room in two days. Its hard work and we've been experimenting with different consistencies of lime mix. Sometime thin seems to work best other times its more like painting with plaster.
Mostly its a bit like painting clay slip onto pottery. Its grey when painted on, but white once dry - hence mottled effect on walls at present.
Meanwhile, David is getting on with the window frame. Quite a challenge as the hole is not square!