Clunch weathers in many different ways however what we are seeing at the Folly is the semi hard face of the stone eroding in patches which leaves a soft fragile core face of stone exposed. These areas are more susceptible to weathering and the decay accelerates as the water gets into the stones and it crumbles fast. In addition once the outer face is lost it reveals the original light cream stone colour which looks blotchy when viewed against the rest of the surrounding stone, the original has built up a patina over the last 240 years. We had a building which looked like a Friesian Cow, patches everywhere.
The conservators have been using their artistic touch to colour these areas to match the surrounding weathered and aged stone – the appearance is to capture the years of lichen and algae growth.
Not only will it blend with the surround stones but more importantly the coloured lime wash (shelter coat) holds the fragile surface in place (called consolidation, it will bind the surface but allow it to breath. They have an artist’s palette of colour at hand and use a mixture of ingredients, greys, greens, browns, creams and whites.
What’s in it … We use a base coat to add the background colours, this consists of : 5 Litre of “Cennini” limewash with casein 5 Litre of water 2.5 Tablespoons Cotswold stone dust 5 Tablespoons Raw Umber pigment and then over this the splodges, sponge effect, lines, with a typical green colour as 750 ml of the Base Mix, limewash with casein 25 ml Terra Vert 10 ml Raw Umber 5 ml Y47 Raw Sienna 2.5 ml Yellow Ochre 1 ml CSK Black there are then the other 5 colour mixes which are individually toned to make sure the Tower of the Folly looks perfect but is well protected.
They even add the white moss / lichen growths.
So can you spot the coloured patches.