Issue 38 Summer web 23 - Flipbook - Page 47
Restoration of the Internal Decorative Scheme
The first step in restoration of the internal decoration
scheme was to gain full access to each of the panels, which
involved erection of a complicated birdcage scaffold,
carefully designed so as not to overload the existing structure. The main weight of the scaffold was designed to rest
over the central portion of the floor, located directly over
the stone vaulting of the Exchange below as this could
take more weight than the suspended floors at either end
of the hall, which needed to be back propped down to
basement level.
Initial trials carried out at RIBA Stage 3 from a tower
scaffold had revealed up to a total of 7 layers of impervious
varnish had been applied over the lifetime of the Town
Hall to both the plaster panels and the timber beams.
These commercially prepared varnishes, commonly
applied to decorative surfaces in the mid-20th century,
harden by oxidation and become progressively more
insoluble and yellow as they age. Further trials were
undertaken to a wider selection of panels and timbers
once the scaffold had been erected to ascertain the best
methodology for safe and effective removal of surface dirt
and varnish to underpin the development of a sound and
scalable methodology for the conservation of the ceiling
decoration. Methods of investigation included a visual
assessment of the ceiling in reflected, raking and
ultraviolet light, localised cleaning trials, and paint
sampling and analysis.
Above, figure four, Great Hall ceiling cleaned
Above, figure three, removal of varnish from ceiling panel
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