Hall Conservation Ltd

Date:13 May, 2018

Project Information

The Appleton Water Tower is located on the Sandringham Estate, Norfolk. It was constructed in 1877 to improve the water supply to Sandringham House and the estate. The tower was built from red bricks and local stone which work together to form an attractive decorative pattern up sides of the tower.

At the very top of the tower is a water tank that was constructed using cast iron panels bolted together with lead putty as a gasket. The tank can hold c.32,000 gallons of water and requires additional internal bracing to prevent the cast iron failing under the pressure of so much water. The external walls of the water tank are decorated with cast iron columns and spandrels.

When we surveyed the structure in the autumn of 2017, we found the cast iron panels to be in good condition with only the paint showing signs of failure. The applied cast iron detailing, however, was in a poor condition. Several of the columns had holding repairs some of which had failed.  We also found numerous cracks and that some of the elements were pulling away from the side of the water tank.

The cast iron elements were removed from the water tower and transported to our studio where their condition was fully surveyed and documented.

To undertake the repairs it was essential to remove the paint from the cast iron. The cast iron elements were carefully shot blasted ensuring that the identification labels remained in position.  Their condition was again assessed and any additional damaged noted.

The spandrels were found to be more cracked than the original survey suggested, and the paint removal also revealed additional cracking on the columns.

After trials, the decision was made to braze repair the cracks rather than weld them. The length of one of the intact columns was measured to ensure that all of the columns to be repaired would be the same length and fit with the existing holes in the water tank. The columns were laid out individually and clamped to ensure they would not move during the brazing process. The break edges were then ‘V’ prepped to ensure a clean edge for brazing, giving a larger surface area for the braze to adhere to creating a stronger join.

The columns were pre heated using a propane torch to prevent thermal shock from occurring before heating the cracked area with an oxy-acetylene torch. Once the correct temperature had been reached, the braze was applied, after filling the crack the column was allowed to cool down slowly, again to prevent thermal shock. Once cool, the braze was fettled to match in with the surrounding modelling.  Due to the nature of cast iron, the braze repairs alone could not be relied upon to hold the columns together.  To prevent the cracks in the columns from opening up again the joints were also mechanically fixed.

The spandrels were repaired using the same method as the columns.  They were more problematic because of the different material thicknesses across the sections. Some of the cracks reopened after brazing as the material cooled.

These cracks were vprepped again to ensure the metal was clean before brazing small sections and allowing the material to cool slowly between the brazing. The cracks were again braced using stainless steel plates which were mechanically fixed.  Following the repairs, all of the cast iron was treated using Jenolite®, a corrosion convertor. The ironwork was then painted.

Many of the wooden dentals were completely rotten, these were removed during the first visit to site along with an example of an intact one to use as a template. The new dentals were cut to match using a soft wood.  These were replaced into position on the water tower when the other elements of the project were returned.