Soda Blasting Re-Opens Heritage Building
We are an approved
stone restoration and heritage building cleaning contractor for the Welsh
Government's historic environment service (Cadw) and the National Museums of
Wales. We are proud that our soda blasting team helped with the re-opening of
one of the heritage buildings at St Fagans National History Museum.
St Fagans
St Fagans National
History Museum is one of Europe's foremost open-air museums representing the
life and culture of Wales and is situated in 100 acres of parkland near to
Cardiff. It was opened to the public shortly after the second world war and
since then, over 40 buildings from different periods have been re-erected here
making it one of Wales' most popular heritage attractions.
The nature of the
problem
We were called in as
one of several stone cleaning services to look at the problem of renovating a
fireplace flue in Cilewent Farmhouse. The interior of the flue had become a
fire risk due to the build-up of tar and resins from centuries of use. We met
with the museum authorities and our site manager was greeted by the sight of
around 50mm thickness of deposit requiring removal. The feel and appearance of
the layer requiring removal was that of a very hard tar.
The solution - Soda blasting
Following our initial
appraisal of the issue, we recommended that our soda blasting method of stone
restoration would be the best solution for the conservation of the stone flue
in this fine heritage building. The conservation architects and curators
approved a trial which duly took place.
Soda blasting is a
gentle form of blast cleaning that is particularly effective for the removal of
organic deposits such as bitumen and tar. It uses bicarbonate of soda as the
blast material. When this hit the surface undergoing cleaning, the small
crystals shatter and the energy from this disrupts the surface of the
contamination. The contamination is then simply blown off by the compressed air
flow.
There are two reasons
why it is a safe method for heritage stone restoration. Firstly, it works from
the outside, removing layer after layer until the stone is reached.
Conventional blast cleaning relies on the blast medium breaking the bond
between substrate and contamination piecemeal and is therefore much more
aggressive to the heritage stone beneath. Secondly, bicarbonate of soda is a
material that is only as hard as talc. It is therefore much softer than
stonework and will not scratch or abrade it once the contamination is removed.
In a flue, this is excellent news as any parging is likely to be soft and
brittle so soda blasting will leave it intact, however, at St Fagans, there was
no parging, the flue was stone and brick lined.
Following the trial,
we were duly appointed as the stone cleaning contractors. Prior to starting, it
was necessary to clear the room of furniture and to seal the fire opening to
contain the waste from the stone cleaning process. To achieve the latter, we
used a framework and sealed the edges against the hearth and fire surround
using tape.
Since it was a large
single flue, there were no withes to hinder the use of a portable lift to
enable our technicians and their soda blasting equipment to access the whole 25
metres of the opening over the course of 3 days of cleaning. The waste from the
cleaning was simply brushed and vacuumed into our waste containers for
transportation and disposal, in accordance with environmental legislation.
Once the cleaning was
completed and our equipment back in the vans, the furniture was re-instated and
St Fagans could make the room available to the public once again. If you have a
listed building or are a manager of a heritage site, contact us to find out how
we could help you with any heritage building restoration projects that you may
have - APT are
the leading soda blasting company in the UK. Ring 01495 308048 now for help and advice with your brick cleaning or
architectural masonry renovation requirements.
