Page 42 - Historic Churches 2013

42 BCD Special Report on Historic Churches 20th annual edition CATHEDRALC O M M U N I C A T I O N S
PAINTING RAILINGS
John Wilson
F rommodest 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
Coalbrookdale gates to St John’s Church, Devizes:
the ironwork needed repairs after suffering a vehicle
strike (top left). 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, recoatable, aliphatic polyurethane mid-
sheen finish coat (Protegathane PLS(HS).
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.