The Historic Metalwork Conservation Company has been able to work on wide variety of different types of project over recent years.
Califat Boiler, Swannington
The Califat boiler is what is known as a ‘Haystack’ boiler due to its shape. It sits in the Califat Spinney close to the village of Coleorton in Leicestershire. The boiler is of national significance and is a rare example of its type being used with the first successful steam engine, the Newcomen atmospheric engine, introduced in 1712.
The Califat Boiler was found in the Spinney in 1969 by local industrial archaeologists. This area had a number of coal mines and it was last used as a water storage tank. It was originally restored by Leicestershire County Council in the 1970’s. It was returned to Coleorton, being loaned to the Swannington Heritage Trust in 2011.
Peter Meehan ACR of HMCC Limited, was contracted by Leicestershire County Council’s senior curator to undertake a detailed conservation report in March 2018 with options for its stabilisation and treatment in the short, medium and long term. The boiler was sited under a wooden roof to give it some weather protection and had a black bituminous paint coating present. There were also some glass fibre repair patches fitted during the original restoration. There was some dirt and algae growth present on the surface. Original paint layers survived on the wrought iron plates inside and was evident under the bitumen paint outside. Corrosion had occurred where the cast iron pipe fittings joined the wrought iron boiler.
In March 2020, HMCC was appointed to carry out some short term conservation work to the boiler in order to stabilise it as part of a plan to move and re-display the Boiler at the same site. It was first thoroughly cleaned to remove dirt and algae accumulations using stiff wire brushes, before lose bitumen paint layers and rust were removed back to a sound surface. This process exposed much of the original red lead primer layers beneath. These were still providing protection to the original iron surface. Rust patches were treated with a commercial rust converter made by Loctite in order to stabilise them. The outer surfaces of the boiler were then protected with two coats of an alkyd primer-finish coating; Sherwin-Williams Kem-Kromik 155 primer / finish. The glass fibre patches were lightly cleaned and very loose edges secured but were left in place.
St Peter’s Church, Daylesford
St Peter’s church was designed by the Victorian architect, John Loughborough Pearson and completed in 1863. It was built in a high gothic style. Features included two wrought iron transept screens with their original paint scheme surviving. These are believed to be by Francis Skidmore, a well known craftsman and leading figure in the Gothic Revival Movement.
HMCC Ltd was first contracted by the project architect Donald Insall, to carry out a survey of the transept screens, altar rail and wall lights as one of a number of inspections, before preparing a report recommending suitable conservation treatments.
The ironwork was very ornate with many decorative elements, all finished with lead-based paints, with some areas highlighted in gold leaf. The original paint had survived but was found to be every dirty with some losses due to localised iron corrosion, probably as a result of condensation during cold weather periods.
The client subsequently instructed HMCC Ltd to carry out the conservation recommendations contained in the original report in order to clean and stabilise the screens, altar rail and wall lights. This was done as part of improvements to the fabric of the church building.
The ironwork was first cleaned by brush and vacuum to remove accumulations of dust and dirt. The painted surfaces were then further cleaned using a series of fine grade abrasive pads to remove remaining ingrained dirt. A small brass brush was used to remove minor rust deposits to bare iron surfaces.
Once cleaned, the remaining paint layers were consolidated using a 5% solution of an acrylic resin dissolved in white spirit and normally used in the treatment of oil paintings. The treated surfaces were then protected with a coating of Renaissance microcrystalline wax applied using a soft brush.