NHIGFerrous Metals Seminar draws a crowd
Our Ferrous Metals Seminar, held at the National Maritime Museum in London in February, drew a large crowd of architects and conservation and restoration professionals ready to broaden their knowledge of our favourite subject. There were presentations by our board of experts and plenty of questions and comments from the audience.
The seminar was followed by a tour of the first classically inspired building constructed in England, Inigo Jones’ 400 year old Queens House.
The focus of our interest in this was the Tulip Stairs, with their superb blue-painted wrought iron balustrade, restored recently by Hall Conservation, who recreated the “smalt” paint technique of the time, which involved grinding up cobalt glass and sweeping the dust into the paint base in situ to create the tactile matt surface and subtle colour.
Don’t miss the next seminar on Recording & Surveying at Hartlebury Castle – keep an eye on our events for more details.
The latest NHIG seminar was held at the National Maritime Museum in Greenwich. It attracted over 40 delegates from architectural and conservation backgrounds as well as practitioners, and proved a great opportunity for networking.
The seminar opened with a welcoming address from our chairman, David James. David gave a potted history of the National Heritage Ironwork Group, including the writing of National Occupational Standards for Conservation of Ironwork, the training of students through the Heritage Lottery funded bursary scheme and the development of Conservation Principles, which have since been adopted by a growing number of organisations.
- Chris Topp gave the first presentation on wrought iron production, types and grades. He started with a brief history of wrought iron and went on to describe the production methods for charcoal iron and puddled iron. He then talked of how wrought iron can be identified and the different grades and their uses. This is most helpful information when dating ironwork. He also spoke of the structure of wrought iron and how the laminated slag layers, formed in the smelting process, promote corrosion resistance making it superior to those of mild steel and pure iron. His second presentation was on the repair methods of historic iron, making use of examples from his own portfolio to demonstrate the methods of conservation employed in his own workshop. He identified typical examples of corrosion and how they may be repaired and how to work with wrought iron. His presentation finished with him covering recycled/rerolled wrought iron which is available from the ‘Real Wrought Iron Company.’
- Geoff Wallis followed Chris with a presentation on cast iron production and types. He started by looking at the properties of cast iron and the production process that creates it, describing smelting and casting and its historical development. He spoke of the qualities of cast iron, its strength, fire resistance, how it was developed particularly for the construction industry. Geoff also covered how it influenced Victorian society from the creation of decorative buildings like the Royal Botanical Gardens to iron coffins sold as “Anti-Resurrectionist caskets.” Geoff also spoke of the relationship between cast and wrought iron and its development. His second presentation went on to discuss various repair methods and techniques. Firstly, he looked at the casting methods, pattern making and the potential common flaws that arise from the design process. He then described the corrosion issues with cast iron usually due to the contact with other material such as wrought iron. He then went on to discuss the repair methods, welding and the inherent problems and mechanical. He used examples from his own portfolio to as illustrations.
- David James brought us up to date with a presentation about the use of mild steel in historic ironwork. He used case studies from his own portfolio to illustrate the potential confusion between mild steel and wrought iron and how to use design and corrosion patterns to distinguish the difference between them.
- Katrina Redman gave an interesting session on the relationship between ferrous metals and other media such as wood, masonry, lead etc. She spoke of the corrosion issues that arise when ferrous metals are used in conjunction with different media and how they can be overcome. She used an example of a stone arch that had recently become unstable due to the corrosion of the existing ferrous supports and the repair techniques previously used.
- Adrian Legge took us up to lunch with a historical timeline. He covered 4000 years in 20 minutes which was succinct to say the least.
- Lunchtime offered the opportunity to catch up with old friends and make new ones and also peruse some of the fine exhibits in the National Maritime Museum.
- Dana Goodburn-Brown was the first speaker after lunch, and she gave a fascinating insight into her work researching archaeological finds from an Anglo Saxon cemetery in Sittingbourne. She spoke of her use of x-ray and electron microscopy in the identification of ancient relics and the physical make up of metallic objects.
- Eric Nordgren from Cardiff University spoke of his research into the effects of corrosion on wrought iron artefacts before and after conservation treatments.
- Andrew Naylor’s presentation identified issues that arise when dissimilar metals are used together in a damp environment. This is known as electro chemical corrosion. He used examples of how iron nails corroded very quickly when used to fix copper sheets on wooden ship hulls and how simple insulation between the iron and copper slowed the process down significantly. He also spoke of how this discovery led to the use of sacrificial metals to protect ironwork.
- Brian Hall’s presentation was on the effects that corrosion, stress, and embrittlement have on repair methods of ferrous metals.
- David Staley’s presentation was about his research and testing methods to date wrought iron. He talked of his research into the effects of various heat treatments and the use of electron microscopy.
The mid-afternoon film starring Geoff Wallis, consolidated the day’s seminars with a practical look at how cast iron and wrought iron are produced, as well as their history and how they are affected by corrosion. He continued to use case studies from his own portfolio to illustrate repair and conservation methods. This just left time to visit the Queen’s House and see the beautiful Tulip staircase nearly 400 years old which Brian Hall and Hall Conservation have just finished restoring with an interesting talk on the smalt paint system used.