Expert Roger Hunt advises on maintaining metalwork
Old metal railings and other exterior metalwork need regular care and attention to prevent decay, so find out how to spot and remedy the signs of wear and tear
Gates, railings and other items made from wrought iron, cast iron or steel are as much a part of our architectural heritage as the stone and brick of the buildings with which they are associated. Although seemingly robust, these metal adornments can suffer corrosion and ultimately failure through lack of maintenance. Repairs will require the skill of a good craftsperson.
Maintenance checklist
● Check metalwork for rust, corrosion, fractures and other damage
● Note areas of flaky, chipped or discoloured paint
● Identify the cause of rust staining to surrounding masonry and render
● Investigate cracking to masonry where ironwork is embedded
● Clean off dirt, moss or plant growth covering metalwork
● Oil or grease moving parts, such as gate hinges and latches.
Questions and answers
Alex Coode, managing partner, and Kate Jennings, partner of specialist metal conservators, Gloucestershirebased Coode Conservation Partnership, answer common questions about the best methods of repairing and renovating metalwork. Q What are the main considerations when undertaking work?
Try to retain as much of the original as practical. Ideally, repairs should be in the same materials as the original or, where this is not possible, the closest available alternative. Another crucial factor will be the skill of the person doing the work; a poor repair can cause more problems in the long run than no repair at all. Q How often should maintenance be carried out to metalwork?
Most problems are visually obvious, but maintaining coatings is a common blind spot. Once they have started to fail, it becomes much more of an issue to rectify. It makes sense to follow a schedule of recoating metalwork every five to seven years. Any build-up of soiling or organic growth on the coating will reduce its life, as will a build-up of vegetation or detritus around the lower areas. Q What are the major differences between wrought iron, cast iron and steel, and their uses?
Wrought iron and steel share most properties, and they can both be used to make traditionally forged work, although they behave differently when forging. A few per cent more carbon
content makes cast iron quite a different metal. It is brittle and will tend to break rather than bend. Consequently, it works well under compression but not under tension. Q The railings of my Georgian house are badly rusting; what should be done? Loose rust and poorly adhering paint should be removed. If structurally sound, the railings can be recoated. Most are heavily over-engineered, so some material can be lost without fear of failure. If the fixings to the ground and top rail are failing and blowing the stone apart, then they will need to be addressed. Q At the junction with a wall, the metal of the railings has corroded, fracturing the stonework; how can this be repaired? If the fracturing is bad, the stone may need to be replaced, with an indent cut to receive the rail. The fixing, lead or resin can sometimes be drilled out after cutting off the end of the rail. Once the hole is cleared, the end of the rail can be reattached – once treated for rust – or replaced, depending on condition, and then refixed into the hole. Q What should be considered when buying ironwork from architectural salvage yards?
Ask about provenance as this could give an idea of age and the materials used in construction, helping inform any repairs. Look for corrosion as this may not be straightforward to rectify; painting over the compacted rust will not stop it from rusting and deforming further. With gates, check that they are square and not buckled. Q Should old paint be removed? If it is well adhered and sound, then no. If the layers have built up to such an extent that details are being obscured, stripping and starting again can be considered. If stripping is done, a paint sample should be taken by chipping some off, with the lowest layer used to inform the new paint colour for historical accuracy. Black ironwork is a modern fashion; a great variety of colours can often be found in samples from old ironwork. Q How should paint be stripped? If metalwork can be removed, there are three main options. Blasting is relatively cheap and leaves a good key for coatings. Dipping is effective but can leave corrosive residues in crevices that undermine new coatings. Flame cleaning is slower and more labour intensive but more effective; it is particularly good with delicate areas that might be damaged by blasting.
If the metalwork is to remain in place, blasting or flame cleaning could still be considered, although their use will depend on a range of factors. Removal of paint using hand tools is
Above: Follow a schedule of recoating metalwork every five to seven years and also keep a check on build-up of vegetation effective, but more labour intensive. Before the 1960s, metalwork would probably have been painted with paints containing lead, so relevant safety procedures must be followed when stripping. Q What paint should be used and how many coats should be applied? There are many opinions. A good, traditional oil paint, brush applied, will be compatible with old layers. It should give five to seven years of effective life, is easy to maintain in situ while also being relatively straight forward to reverse. Two coats should be sufficient, on top of a zinc-rich primer, if coating bare metal. Time and money spent on good surface preparation, a high-quality primer and topcoat paints, while making sure no areas are missed when painting, will pay dividends.