Painting Railings

John Wilson

 

  The church exterior with repaired gates, railings and piers with a black mid-sheen finish Damaged gate and pier before repair
  Coalbrookdale gates to St John’s Church, Devizes: the ironwork needed repairs after suffering a vehicle strike (above right). The gates and piers were removed to the workshop where new internal strengthening frames were built to support the fragile cast iron. One of the pier caps had a piece broken out of it which was repaired by setting in a new piece of cast iron moulded to the original profile. The three-coat paint system used comprised a high solids, epoxy aluminium primer (Protegabond ST200); two-pack, high solids, epoxy intermediate coat (Protegabond WG500); and two-pack, re-coatable, aliphatic polyurethane mid-sheen finish coat (Protegathane PLS(HS).

From modest rural chapels to grand urban churches, historic places of worship of all sizes have railings and gates in wrought or cast iron. Iron window frames are also common. All require routine maintenance including regular painting. Paints not only enhance the appearance of ironwork, they provide vital protection from corrosion by serving as a barrier to air and water.

CHOOSING A PAINT SYSTEM

In this context, the term ‘paint’ is actually shorthand for ‘paint system’, meaning a suite of paint products from primer through to final coat. A paint system might be a traditional lead- or oil-based type, or it could be one from a family of modern synthetic products.

The repair and maintenance of historic fabric should normally be carried out using historically authentic materials, but paint presents some difficulties here.

Lead-based paints, which were used widely for generations, offer excellent performance and have a distinctive sheen. However, environmental legislation has prohibited their use except on scheduled monuments and the most important listed buildings (Grade I and II* in England and Wales, and category A in Scotland). Permission to use them may be obtained by application to English Heritage or its counterparts in Scotland and Wales via one of the few remaining manufacturers. Applications must include details of the planned use and quantity needed, although the latter can be difficult to estimate when painting elaborate wrought iron railings and gates. Procurement can be a lengthy process.

Other traditional oil-based paints are widely available, typically containing titanium dioxide rather than lead. They dry slowly to a film that remains soft for some time so newly-painted items can be difficult to handle when they are transported from workshop to site. Painting on site presents less of a problem but adequate drying times are needed to prevent mating surfaces from sticking together (for example, where gates meet or metal windows close).

Modern paint technologies have a lot to offer. The coatings that make up a particular paint system can be relied on to work together, physically and chemically. Manufacturers provide specifications for preparation, film thicknesses and methods of application so that a quality result is assured. Each coat cures quickly and adheres firmly to the work. However, the most powerful argument for using a modern paint system is durability – some two-pack paint systems have a projected lifespan that exceeds 25 years.

COLOUR AND SHEEN

  Coalbrookdale marking on the primed (pink) face of one of the piers Reassembled pier with white intermediate coat
  Both piers in the workshop with black finish coat applied The gate posts in the workshop of Calibre Metalwork (above left) after blast cleaning and priming with an epoxy aluminium primer; (above right) after repair and with the two-pack, high solids, epoxy intermediate coat applied, and (left) the final coat showing the subtle reflections of a mid-sheen topcoat (an aliphatic polyurethane)

Analysis of paint samples taken from ironwork can be used to identify previous colour schemes. The results need careful interpretation to differentiate between the colours of undercoats and topcoats, and to allow for any yellowing that may have occurred in the oil medium. Whether or not there is any intention to replicate historic colours, the analysis provides a valuable historical record which would otherwise be lost to paint stripping.

Some of the older paint technologies are limited in colour range. A colour palette contemporary with your ironwork can be researched to assist with selection.

Given a free choice of colour, specifiers tend to ask for black with gold highlights before giving the matter any real thought. Subtle greens, rich maroons, and warm browns can look very distinctive in both urban and country churchyard settings.

Whatever the decision, it should be made in plenty of time. Undercoats are toned to support the colour of the final finish and workshop painting begins earlier than many people realise. Painting should not be rushed.

Sheen levels also affect the overall appearance. The surfaces of hand-forged work do not have dead flat surfaces, so a high gloss finish looks wrong. A mid-sheen finish produces a better result on wrought and cast work. Oddly, project specifications often fail to mention sheen.

SURFACE PREPARATION

  A man in a hard hat and high vis jacket painting railings in situ
  Applying the finish coat to refurbished cast iron
railings at 107 Great Mersey Street, Liverpool: the paint system used here is Protegabond ST200 two-pack epoxy aluminium primer and Protegathane
PLS(HS) two-pack re-coatable aliphatic poly-urethane in graphite black with mid-sheen finish.

Preparation depends on where the work is to be done. Ironwork that has deteriorated badly or has been accident-damaged, usually requires full workshop facilities. This enables the blast-cleaning, repairs and painting to be undertaken in controlled conditions.

Repainting ironwork in situ, when practical, saves disturbing associated masonry. It can save on cost too but it may not be a sensible longer term option if water has penetrated inaccessible areas. This might show as damage to stonework caused by the expansion of rust. Removal and thorough treatment is the only long-term solution. Mobile blast cleaning services can remove old paintwork on site, but method statements should be checked to ensure that adequate masonry protection is put in place as well as any necessary noise and dust control measures. There is a case for not removing old paint if it is well-adhered to the iron, although knocks and chips in a heavy build-up of old paint are difficult to flatten out by local treatment with abrasive papers. While some surface variations contribute to a sense of history and age, old chips that are too prominent beneath a new paint layer leave everyone dissatisfied.

APPLICATION

Painting is a skilled job which is easy to underestimate. No matter how skilled the metalworking element of a project, most people will judge the quality of the work by the paint finish.

For on-site painting it is a sensible precaution to allow a little extra time to allow for unsuitable weather, be it cold, rain or both. Wet paint that has been rained on will show blemishes. The only cure for this is the application of another coat.

Ironwork ought to shed water whenever it can be engineered to do so. Leaves and scrolls in wrought ironwork make it particularly vulnerable to water-trapping. Careful use of lead putties to fill pockets will reduce the problem. Epoxy fillers are used to seal joints.

Spray applications produce the best results in the workshop. Smaller one-off items tend to be brush-painted. Two-pack paints must be mixed in the correct ratios and used before they ‘go off’. It is this chemical reaction that produces the fast-curing characteristic, enabling work to be handled soon after painting.

Close-up showing an evenly coated cast iron railing detail  
It is important to achieve an even, continuous coating with the brush.  

For paint to perform as an effective barrier it must flow over the work to form a continuous wet film of the correct thickness, and it will then dry as a continuous protective coating. A poor spraying technique will produce patchy results. If a paint film is too thick it will tend to sag and run. A spray gun held too far from the work or used in short blasts will cause the paint to hit the surface ‘dry’ producing a rough surface that has no film continuity. Skilled brushwork will produce the continuous film required without patchiness, runs or drags. Small rollers may be used on palings.

Paint ‘misses’ are avoided by using different shades for each coat (for example, an off-white undercoat for a white topcoat). Specifications sometimes set out the shades to be used for each coat so that they can be readily identified for inspection and approval.

Film thicknesses can be measured with equipment ranging from simple pocket mechanical devices through to sophisticated electronic instruments such as those manufactured by Elcometer.

During on-site painting it is important to ensure that adjoining surfaces are properly protected. Where ironwork meets masonry, the latter should be masked off. Method statements should state how general fabric will be protected (not simply that it will be) and how spills would be addressed.

AFTERCARE

Finally, there are a few simple measures to keep new paintwork in good order:

  • Provide for repair or replacement of locks in specifications for gates, including the number of keys required. This eliminates the need for chains and padlocks which can quickly damage paintwork and look unsightly.
  • Consider how gates are to be held open. Various types of holdback latch can be made and installed with the refurbished gates.
  • Gates may need adjusting at the hinges from time to time so they close correctly. Address this promptly should the need arise.
  • Inspect all ironwork annually and touch-in any paint chips and scratches with an appropriate product. Clear away any vegetation (ivy growth, leaf debris) that might prevent ironwork drying out after rain.

 

 

 

Historic Churches , 2013

Author

JOHN WILSON is contracts director at Calibre Metalwork Limited. His interest in conservation began while he was working for a commercial developer converting Wapping and Waterloo dock warehouses in Liverpool for residential use. His interest in the building preservation trust movement includes raising funds to rescue the Grade II* Plaza Cinema in Stockport.

Further information

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Churches (general)

Metals

Paint

 

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Wrought ironwork

 

 

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