Oyster shells were very good to create lime. The area around Pittwater was very suited to this as many aboriginal middens were located there and the bay was very shallow near the shore so convict workers could be sent out in the water to collect other shells suitable for lime making. But this could be dangerous as noted in this newspaper article of 1842. According to Peter MacFie’s research, in the late 1830s, Henry Cooper had lime kilns on his property and it is supposed to be near Pitt Water. Could these be at the end of Shark Point Road? Or could they be the lime kilns mentioned in this advertisement of 1829 by Robert Garrett, a surgeon at Sorell.
The steps to create usable lime:
- Collect shells and put in lime kiln
- Heat and burn the shells
- Slake the lime with water
Many of the kilns were inverted bell types shown in photo from Norfolk Island. This is the same as the one at Port Arthur. But the very earliest ways to make lime was to build up a pile of wood, put shells on top and burn quickly to collect the lime.
I put a question to the Sorell Historical Society Facebook page asking about buildings in the district with shell lime in the mortar and where might the earliest lime kilns in the district be. I then visited a few of these places to take some photos.
Shell lime used as a whitewash on the old barn built in 1826 with convict labour. Originally owned by Captain William Henry Glover, an officer in the 31st Regiment of Foot, who had been appointed Police Magistrate of the Sorell District. Talking to the present day owners, there is also a lime kiln on the property at the top of the hill.
Lime was used in mortars and plaster in early colonial buildings. When mixed with sand, it produced a type of cement. In brick buildings, walls were often covered with a lime plaster and outside fences and walls were whitewashed with a lime solution. But for agricultural purposes, it could be mixed with clayey soil to improve the texture for crops.
Readers: Do you have any shell lime used as mortar or whitewash on your property? If you live locally, you might be able to send me a photo to include in this post. My email is on the sidebar of this blog.