
The new lime mortar grouting between the flagstones in the Great Hall at Knole being painted. ©National Trust
The Knole conservation blog keeps providing fascinating insights into the reality of looking after a large and complex historic house.

The Great Hall at Knole. Both the floor and the carved screen date from the remodelling of the house in 1605-1608. ©National Trust Images/Andreas von Einsiedel
A recent post included images of the bright new lime mortar grouting of the stone floor in the Great Hall being painted to make it blend in – a wonderful example of the artifice required to preserve the aesthetic balance in a historic interior.

The floor in raking light, showing the difference in wear between the dark and the light flagstones. ©National Trust
As the Knole conservation blog tells us, the Great Hall was part of the original palace built by Archbishop Bourchier in about 1460, but the Purbeck marble floor probably dates from the extensive remodelling of the building by Thomas Sackville, 1st Earl of Dorset, in 1605-1608.
Over time the black flagstones have been worn away more than the white ones, due to their slightly different physical properties.

Completed map of the condition of the floor before remdial work. Red indicates 70% surface damage, green 10-70% damage, orange 0-10% damage. ©National Trust
Cliveden Conservation recently carried out a survey of the floor in preparation for doing some remedial work.

Conservator from Cliveden Conservation injecting runny mortar into a crack in a flagstone. ©National Trust
The subsequent programme of work included removal of surface dirt, consolidation of flaking areas of stone, injecting of cracks with runny mortar and repointing between the flagstones with lime mortar – and some artful retouching with mortar colour.

July 11, 2012 at 10:17 |
So both colour stones are Purbeck? I’m interested because here (eg the gallery over the bridge at Chenonceau) it is the light coloured stone that has worn, whereas at Knole it appears to be the dark. The stone at Chenonceau is a late Cretaceous limestone (so younger than Purbeck, and fairly soft) and slate I believe.
July 11, 2012 at 12:32 |
The map is a terrific graphic in itself. And the photo of the floor in raking light is beautiful — reminds me of the aesthetic appeal of the upholstery X-rays.
July 11, 2012 at 14:49 |
Susan, that is how I understood it, but I will double-check with the colleagues at Knole.
Slate is an interesting choice of material at Chenonceau, being water-resistant. Some of the buildings in the former Victorian railway works near where I work have a layer of slate built into the base of the walls as am attempt at damp-proofing. But it obviously wouldn’t work in that way if you used it in a chequered pattern floor together with another type of stone.
Courtney, yes this is ‘conservation chic’
July 11, 2012 at 15:39 |
Thanks Emile for your continued support of our blog. Emily
July 11, 2012 at 16:25 |
Emily, not at all – please keep those posts coming
July 13, 2012 at 18:01 |
Your blog is a delight – these posts allow readers just the right amount of access into the intrigue and care of these great houses.
July 14, 2012 at 06:29 |
Fascinating. Thanks for putting this up!
July 14, 2012 at 21:25 |
Keith, Grant, thanks.
July 20, 2012 at 12:21 |
It’s amazing to see what attention to detail is paid. I wrote about the restoration of Grand Central Station in NYC (not nearly as old!) and was fascinated by the challenges involved. Several of the original quarries supplying stone in 1905 had since gone out of business, necessitating different stone from new sources that still had to match visually.
July 26, 2012 at 14:43 |
Broadside, my apologies for the delay in responding! Yes the choice of stone for conservation/restoration is a serious business
I love Grand Central Station, such a sublime space.