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Anyone for Hot Mix Lime? #13

By Lesley Fuller

January 26, 2019

Hot Mix Lime! Petrographic Analysis!

I doubt that many regular readers of our blog will be familiar with these terms, but they entered my vocabulary and grey matter recently.

Under The Leader’s Encore umbrella we offer hands-on support and advice to charities, social enterprises and community groups. So, we recently submitted a comprehensive funding proposal for essential repairs and renovation to the 126-year-old Cove Burgh Hall on the Rosneath Peninsula. Given the Hall’s sandstone façade, I have found myself digging around (not quite literally) to understand the technical challenges when carrying out works on a historic building. Hence the reference to a petrographic analysis, and critically the use of hot mix lime when repairing the sandstone.

Cove Burgh Hall, Circa 1959

From Wikipedia we learn that Petrography is a branch of petrology that focuses on detailed descriptions of rocks. The mineral content and the textural relationships within the rock are described in detail and the classification of rocks is based on the information acquired during the petrographic analysis.

A quick online search of “hot mix lime” tells us that hot mix is the new topic in lime mortars. Basically, over the past 15-20 years a lot of earlier hard cement mortar repairs and repointing of stone buildings have been replaced using lime mortar to counteract the accelerated decay caused to the stone by the hard cement. Current advice is that a hot mix lime mortar is more effective.

The Engine Shed is Scotland’s dedicated building conservation centre, run by Historic Environment Scotland. From its website we learn that sandstone is the main type of building stone used in Scotland. Although a durable material, sandstone is also naturally porous, making it prone to erosion if subjected to water and wind over time. We certainly get a lot of that in Scotland! Correctly used and maintained, however, stone is a sound, stable building material – as shown by our many prehistoric, medieval, Georgian and Victorian buildings.

Expanding your Knowledge Base

I am now much more observant when out and about and had never realised there were so many shades and varieties of sandstone which adorn our buildings, from churches to tenements.

Now my life hasn’t quite been changed by learning these new facts, and I’m hardly going to have much opportunity to bring “hot mix lime” up in day-to-day conversation, but there is something satisfying about having to glean an understanding of a topic which would never usually appear on your radar.

Sandstone on display in Glasgow in the scorching summer of 2018

So back to our funding proposal. Cove Burgh Hall is one of Scotland's most striking community hubs, with a rich red sandstone façade. Opened in 1893, it is a superb example of built heritage positioned at the centre of continuous community and civic service and still the local heart of communal activity.

Situated on the western coast of the Rosneath Peninsula, the Hall is one of the country's community gems, gracefully constructed and beautifully situated. It is in a stunning location with breath-taking views across the Firth of Clyde and Loch Long, and south to the Isle of Arran, Bute and Cowal Peninsula. It is strangely isolated, by dint of being in an area dominated by the Faslane and Coulport Nuclear bases. It is just outside, yet almost surrounded by Loch Lomond National Park. The Hall is part of the tourism renaissance with Loch Lomond and Clyde Sea Lochs Trail, VisitKilcreggan.com and Waverley Cruises, a few of the local attractions; it is indeed, one of Scotland’s hidden treasures.

The dedicated volunteer Board have spent around three years researching the best way to carry out critical repairs to crumbling stonework and fix a range of internal structural issues. To this end, specialist architectural professionals and conservation experts were consulted to ensure that the Board had the necessary knowledge and understanding to prepare and prioritise a programme of repair and renovation. The Hall is well-used and well-loved and its loss would be a real blow to the local and wider community.

What are the Wider Lessons?

In today’s fast-paced environment, leaders need to be able to move out of their own sphere of knowledge and gain an understanding of a wide range of topics, find out about best practice and essentially keep on learning. With the internet there is a danger of disappearing down rabbit holes, or feeling like you are drinking from a firehose, but you just need to ensure that common sense prevails.

If online research is widened to include podcasts, books and articles, the final piece of the jigsaw involves listening and talking to specialists with skills and expertise and deep knowledge of their field. This approach should give any leader enough sound information on which to make an evidence-based decision, whether that’s starting a new business, developing a new project, expanding their business or writing a funding proposal.

Please pass the hot mix lime…

“If you think education is expensive, try ignorance.” 

Harvey Mackay

Take care. Lead well

Lesley