News

News

22 Jan 2010

Marble and Granite Restoration


Preserving our heritage inside museums poses a very different problem from preservation outside, where that heritage frequently has to face the elements.

Inside the museum the restoration of marble and granite is probably less important than the preservation of the objects being cared for.

 

Fortunately the conservation of natural stone objects in the museum has advanced considerably over the last 30 years and today's conservators have an armoury of products to choose from.

Outside of the museum the problems are completely different.  "Heritage" is perceived as buildings, such as stately homes, castles, churches and cathedrals, and it is in such properties that the restoration of marble and granite can present problems.

The cleaning of both materials is not difficult.  There are many products and methods on the market, from simple water washing to complex poultices for removing or diminishing stains.  In the U.K. there are many companies who specialize in this type of work and have the experience to deal with delicate stonework, but it is essential to use an expert.  Stone Federation Great Britain can give you guidance on that.

Where repairs are required this can cause problems for a number of reasons. Firstly obtaining suitable material can be very difficult, especially marble.  The U.K. has very few deposits of marble and what has been quarried has been used in very limited ways, usually confined to buildings in a small area near the quarry.

(At this juncture it is worth making the important point that Purbeck marble is a hard limestone that takes a polish and should be not confused with real marble which is a metamorphic rock).

Because of the lack of indigenous marble the vast majority of marble now in this country has come from overseas, and until more recent times supplies would have come from countries around the Mediterranean.  The consequences of this are that it can be difficult, or even impossible, to get matching material for repairs.

Many of the old quarries are shut or "lost" and if found are not an economic proposition to reopen, assuming permission would be granted.  Diligent searching around the companies specialising in marble, both here and overseas, may turn up some old long forgotten pieces of marble in a corner of the stone yard.

Granite can present the same problems as marble, except that the range of colours and variations of markings are not so prolific.  Furthermore the U.K. has more sources of granite, although not a large colour range, and overseas supplies tended to come from the Scandinavian countries.  Some of those materials are still available today. Unfortunately the majority of U.K. granite quarries are now closed and permission to reopen is rarely granted.

Repairs to both materials require a high degree of skill as neither is easy to work.  They are both hard, and working on site is never as easy as working inside a workshop. Cutting out damaged areas and letting in new pieces needs to be done with as tight a joint as possible in order to lessen the impact of the repair.  This will be easier to do with marble than granite, although, other than impact damage or building movement, granite is less likely to need such repairs as it is not affected by the weather to the same extent as marble.

Marble and the damp U.K. climate are not compatible, the marble going sugary after years in the open.  Bodies such as the National Trust cover up statues during the winter months.

"Plastic repair," or making good, is very difficult due to the nature of both materials and requires a mason with artistic talents.  The more veined marbles can present less of a problem due to the variations in colour whereas a plainer marble, such as Carrara, will be more difficult to make good without being noticeable.

When polished, granite is very difficult to make because of its crystalline structure and "depth".  It is almost impossible to replicate and the area made good tends to look dull as it lacks the sparkle that granite possess.

Cleaning of both materials in situ can be done but repolishing granite in situ is very difficult and should not be undertaken without assessing all the pros and cons and possibly trying a test area before final decisions are made.

Floors are one area that needs constant monitoring.  The foot traffic in a building originally intended for private use, but now open to the public, will be far in excess of anything imagined when the property was built.  This increased use can not only lead to more wear but also dramatically reduce the slip resistance.  This is not necessarily a problem when dry, but could be dangerous when wet.

As I have already indicated, when any work is being considered it is vital to talk to a company that is both experienced and knowledgeable.

Stone Federation Great Britain can help with names of suitable companies and for more information you should contact them on 01303 856123 or by email to enquiries@stonefed.org.uk.

The Federation is a valuable source of all sorts of information relating to natural stone.  It is the industry's official trade association, representing employers, liaising with Government on legal affairs, health and safety, technical standards and also developing craftsmanship, training and education.

It produces extremely informative and helpful publications, such as its code of practice for the design and installation of internal natural stone flooring.  Again, details are available from the Federation.

 

 

Members' News

Stone Federation would like to congratulate former Stone Federation President, Peter Harrison for being the recipient of the stone industry's highest award, the Duke of Gloucester Gold Medal.


Peter was presented with his medal by the Duke of Gloucester himself at Worshipful Company of Masons' Master's Banquet in London's Mansion House.


The Medal, which was introduced in 2010, is awarded every two years, to honour an individual in the craft of stonemasonry or the natural stone industry whose work is of considerable merit and who is acknowledged by his or her peers for the excellence of their contribution.


The idea for recognition for those in stonemasonry was originally mooted in the 1980s when it was noted that stonemasonry did not have any kind of recognition or a supreme accolade.

 

His Royal Highness The Duke of Gloucester, who trained as an architect and has an affinity for stonemasonry, also felt that some form of recognition should be created and was instrumental in developing the concept of a recognition for stonemasonry befitting the millennia-old craft.

Stone Federation are a member of EuroRoc, an organisation made up of the various European Federations for the dimensional stone industry.  The aim of the group is to coordinate questions of common interest and find solutions while promoting the use of dimensional natural stone.

 

The Federation's EuroRoc representative, Michael Poultney of Albion Stone along with Peter Harrison of Harrison Goldman, attended the latest meeting held at the Verona Stone Show in October.

 

There were a range of topics discussed, but shown are four discussions points that will be of particular interest to members.

 

1. Ethical Sourcing - There are various different degrees of controls of ethical sourcing across Europe and some is at a very local level.  It was accepted that the EU should be encouraging stones from ethical sources but there was some scepticism that a system with a high degree of certainty could be found in the short term.  It was agreed that the starting point should be to pool all the experiences from the differing methods currently being used by different, Countries, companies and organisations.

2. Geographical Protection - There was considerable support from across the EU and the robust comments from the UK were considered positive.  It is back with the European Parliament on what could be a long journey to possible implementation.  

3. Reporting Figures - There was concerns that the code numbers used for reporting production, imports and exports are not recording the dimensional stone figure accurately.  It was suggested that these should be related to the harmonised Product Standards (BS EN). Michael Poultney has been in dialogue with BGS and Eric Bignell at the Natural Stone Specialist magazine about the topic earlier in the month. Euroroc will progress the matter with the relevant authorities.

4. Silica Dust - There was a mixed response about the danger of the implementation of the dust regulations and the prospects of reducing the code.  It was agreed that the experiences from the implementation from national authorities will be requested.

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With the island of Portland, from which the famous Portland limestone comes, being just off the Dorset coast from Weymouth, there could not have been a more appropriate material to use for a sculpture of the Olympic rings that has now been installed in the town that is hosting the Olympic sailing events. 

Burlington Stone has acquired the rights to quarry at Petts Quarry on Kirkstone Pass and Brathay Quarry near Ambleside following the regrettable demise of Kirkstone Quarries Ltd.

This new monument, costing £5 million, will commemorate the 55, 573 crew members of the RAF's Bobmer Command who were killed between 1939 and 1945.  The average age of those who lost their lives was just 22.

Albion Stone has recently purchased a new ‘JCB Fantini’, tractor mounted stone saw which will be used to increase efficiency in the Quarry & Mine.  This is the first machine of its type to be imported into any UK stone extraction operation. 

 

TV presenter, journalist and former conservative politician and Cabinet Minister, Michael Portillo made a fascinating tour of local natural stone producer, Burlington Stone of Kirkby-in-Furness, shown on 26th January on BBC2 at 6.30pm, as part of series three of the BBC’s popular travel documentary, Great British Railway Journeys.

 

A £500,000 investment into an innovative new roof for Albion Stone’s Factory is set to save thousands of pounds a year on their electricity bills.

Albion Stone supplied over 3m³ of Jordans Basebed and Jordans Whitbed in the form of treads risers, paving and memorial stones.

Taking centre stage on The Marshalls Garden That Kids Really Want! at the 2008 RHS Chelsea Flower Show in May the company utilised its own indigenous natural Yorkstone block to create two striking central features in this amazing organic playground.