Challenges associated with carrying out essential restoration work to Lerwick’s town hall have been highlighted.
The Shetland Times has been given access to the town’s civic centre as work to restore its stained glass windows and crumbling stonework gathers pace.
Restorers have heaped praise on the artistic skills used in the creation of the stained glass panels, now badly in need of work as part of a £1.7 million project.
But previous work carried out in the early 1990s has led to difficulties for the small team of workers tasked with helping bring the building back to its former glory.
Previously, the windows were put in place using Portland cement and Bitulastic – a kind of sealant – which resulted in the windows becoming stuck in the stonework.
Today’s restorers are forced to chip away at the stone, causing damage to the windows’ “sacrificial glass” – the glass lining at the edge of the panes.
Weaknesses behind the quality of Derbyshire sandstone used during the previous refit have also been highlighted. That is because of the salt air which has eaten into the stonework over the last 25 years.
The main contractor is Aberdeenshire-based LTM Group. But Cannon MacInnes, of Glasgow, is the organisation behind the restoration of the 135 stained glass panels. Its recent works have included the refurbishment of the Royal Apartments at Stirling Castle as well as the restoration of two Ballantine windows in the nearby Wallace Monument.
Here, it has set up a workshop across the road from the town hall in the old library building.
Conservator Linda Cannon says a 1990 restoration has led to a number of challenges.
“The installation of the windows has caused real problems, because they’ve been set into the stone groove. There should be movement within the stone groove of the window once you take out the mortar,” she said.
“But what we’ve found is they have been put in with Portland cement and Bitulastic, which means that there is no movement at all – no give.
“That means that the windows themselves are stuck completely in the stonework. We’ve had to cut the stonework round about it. This has caused damage to the sacrificial glass.
“We’ve also discovered that the conservation techniques which were used were using epoxy resins, which were really just being developed in the 1980s.
“They were developed for museum work primarily, and not for external glasses, and what we’ve found here is that the external glass work has not really survived the pressures of driving wind and rain over 25 years.”
Restorers say the work being done now should stand the building in good stead for hundreds of years.
They plan to protect the “whole environment” of the stained glass windows, shielding them with clear panes of glass and bringing them, in effect, inside the building.
“There is going to be nothing outside at all, so it will be much more of a museum kind of environment.”
Restorer Daniella Peltz has come all the way from New York to do her bit. She said restoring the glass was a challenge, but was extremely rewarding.
“It can be painstaking. I’ve been doing stained glass for about 25 years. I started doing it when I was 12, so professionally earning money I’ve been doing it for 25 years.”
Asked what she thought of the quality of the stained glass panels, she replied: “They’re beautiful. They’re lovely examples of 19th century stained glass. I’m enjoying working on them.”
Back at the town hall, site manager Alan Rae, of LTM Group, was giving an update while standing on internal scaffolding in the main hall.
“The stained glass is deteriorating, so what we’ve had to do is cut away part of the stone. The stone is deteriorating inside so this is all going to be renewed.
“Externally, it doesn’t look that bad but when you see it internally it is all crumbling away and has to be renewed.
“The glass is over in the workshop over at the [old] library. The stained glass is getting all boxed up and taken over there.
“It’s a big job. It’s time consuming. Obviously, we don’t want to cause any more damage to the glass than necessary. We’ve got to take time, take it over to the workshop to get it repaired.”
LTM have already carried out similar work on the Inverness Town House, as well as Craigievar Castle, Marsichal College in Aberdeen and Glasgow University.
Mr Rae added the Lerwick Town Hall project was a “big job”.
“The stone, and the whole building actually, just for historic reasons, has to be done with care. It’s an historic building. You can’t cause any more damage.
“It’s a six month project, but when you open things up and see more damage it could go on a little bit longer if necessary.”
SIC councillor Frank Robertson knows plenty about the history of the town hall.
And with an architectural background, he also knows about the shortcomings of the previous restoration.
“The stone that had been used in the town hall was stone from Eday in Orkney. It was red sandstone and was starting to delaminate. In 1993 we set about restoring those delaminated panels. We looked at various different stones and we settled on stone which was Stanton Moor in Derbyshire. It was exactly the right colour and texture. We had stone panels up on display here, and in the weather for over a year, to see how they would do. And they performed fairly well.”
Unfortunately, the sandstone became affected by the salty air in Shetland. That has led to parts of the stonework crumbling, and the need for restorers to take drastic action.