Lime Burning Returns to Park after 100 Years (2)
As part of the Nave Archaeological Dig in August, Mark Thacker supervised some experimental lime burning near the lime kilns at Park near Port Ramsay.
Part Two: Burning with Wood
It is likely that, for hundreds of years, coal has been used in the lowlands to burn lime. However, apart from a small source in Brora, there is no coal in the Highlands and Islands, and limeburners had to rely on other fuels, predominantly wood. This required a great deal of skill in maintaining the kiln at a sufficiently high temperature for prolonged periods, because the energy content of wood is much lower than coal.
After the success in burning with coal, we had a try at burning with wood, using a ton of seasoned larchwood supplied by John Carmichael.
The “kiln” started with a bed of very dry kindling,
placing the pieces of limestone in the centre of the wood pyramid
and firing from the top
Wood was added to keep the fire burning vigorously for 8 hours
After a further 4 hours in hot embers, the product was recovered from the “kiln”
The small pieces of limestone had burned completely, and yield slaked lime on wetting
But the temperature had not been high enough for long enough to burn the larger pieces, which showed slaking only of the surface layers to a depth of around 5mm in some cases.
This was a first experimental burning with wood but there were at least three important lessons: break up the limestone into small pieces; enclose the burning to conserve heat; and have enough dry fuel to burn for longer, say 24 hours.
Our thanks to Ron Livingstone for allowing us to burn lime in the limestone quarry at Park.