Elizabeth Farm is Australia’s oldest European style building, built in 1793 as the home of John and Elizabeth Macarthur. Unrestrained salt contamination has caused substantial structural deterioration. The original house was built with bricks, rendered and marked with Ashlar blocking, the servants quarters and kitchen were built from Sydney sandstone. The sandstone walls were suffering from decay due to high salt contamination caused by rising damp and in some cases previous lateral water problems. Several attempts had been made over the years to try to arrest the problem with limited success.
The “Westox Cocoon” material was used on several of the bad walls after the removal of existing sacrificial renders and lime wash with the aim of reducing the salts to a “safe” level so sacrificial renders or traditional lime wash could be used with some longevity. The Cocoon was applied in two applications, each application being left for two weeks before removal. Analysis was carried out to verify the transfer of salt from the wall to the Cocoon. The first set of samples was taken prior to application, the second set of samples taken two weeks after the first application. The analysis of the samples was carried out by the CSIRO.
An inspection of the areas of desalination work carried out in November 2002 was made in February 2010, and the results are quite impressive, only one small area of salt contamination is visible in the laundry area where the sacrificial render was used and another on the outside wall of the servant’s quarters where the lime wash was used. All other areas including the basement had no visible signs of salt action; even the flag stones on the verandahs which were deteriorating at a very fast rate have no signs of exfoliation after the cocoon treatment. The former curator of Elizabeth Farm Mr. Gary Crocket confirmed that maintenance costs associated with lime washing and sacrificial renders had been reduced dramatically.