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Reviving Hot-Mixed Lime Mortars

As an acknowledged expert on the historic use of hot-lime mortars and singularly responsible for reviving interest in them through his writings at the onset of the 1990s, when misconceptions within both the ‘Lime Revival’ and in that propagated by the nation’s leading Heritage bodies, placed an overemphasis on lime mortars for brickwork based solely on the use of air lime (non-hydraulic) binders, and always slaked to putty.

Encouraged by the late Professor John Ashurst (RIP) to bring this to the attention of all within the heritage sector, and Lime Revival, beyond what he had already published on this within Chapter 5, ‘Mortars’, in Volume 2 of ‘Brickwork: History, Technology and Practice’ (Donhead Publishing, 1994), Gerard published ‘Lime Mortars for Brickwork: Traditional Practice, Modern Misconceptions’ (Parts 1 and 2, Journal of Architectural Conservation, 1998) and, later, ‘The Myth in the Mix’(2002).

In the latter publication Gerard revealed how historic mix ratios for lime-based mortars recorded within old craft and architectural books were being constantly misinterpreted as being based on hydrated (slaked) limes when in reality these books were discussing the then ubiquitous use of quicklime: aggregate ratios; and that as upon slaking quicklime increases in volume this largely accounted for why the majority of the lime-based mortars that were being used in conservation, repair and restoration works at that time were far too ‘lean’ (binder deficient): and nothing remotely like the lime-rich mortars of their historical counterparts.

The Red Mason has continued to write, lecture and demonstrate about all the varying types of traditional mortars for bricklayers all over the world and his annual ‘Lime Days’ held at the Weald and Downland Living History Museum, running for over 20 years, are celebrated by all who attend.

Though his pioneering work in this area initially met with some resistance – indeed hostility – gradually, however, through his lectures and demonstrations the reality of what he was clearly able to demonstrate and the historical evidence to support this, began to meet with wide-spread acceptance in all quarters and over the past several years there has been a huge revival of interest and use of hot-mixed lime mortars. This viewpoint being emphasised by Hot-Lime enthusiasts stating:- Gerard has always been diligent to keep solely to his craft within his work on hot-mixed lime mortars, witnessing the problems and confusion caused by those who generalise failing to recognise the subtle differences of need and use of bricklayers, stonemasons and plasterers: and those who comment on craft practices they are not qualified nor have meaningful experience in.

To help correct and re-align things on Hot-Mix Lime Mortars in relation to his own craft, Dr Lynch had his paper, ‘Hot-mixed lime mortars and traditionally constructed brickwork’ published within ‘The Journal of the Building Limes Forum’ (Volume 24, 2017) and this was met with huge critical acclaim with comments such as:

  • Brilliant: everyone should read it!

  • Well done with your most comprehensive article in the BLF Journal. 26.10.17

  • With great interest I read your article about Hot-mixed lime mortars in the Journal of the building limes forum. Especially your definition of hot lime and hot-mixed lime is of great value for me because I always had the difficulty to point out that the lime mortar is applied in a hot way. I called these mortars the “real hot lime mortars”. But after your article, and I think it was stressed out in this way for the first time, I hope your definition will be accepted and distributed very soon.

  • Congratulations on an excellent article in the 2017 BLF Journal.

  • It was certainly illuminating and, as to be expected, it read very well. It is good to be so professionally reminded of mortars in brickwork, and on your earlier work on hot-mix

  • Thank you for this excellent paper. It is exactly what is needed at the moment

  • Gerard, what a well-considered article which places the emphasis in all the right places. I think you phased it right, speaking from your experience and knowledge and not straying into speculation

  • I have just read your article and think that it is great. By splitting it up into section and having the pictures it makes the article both easy to read and full of information. As a result of being so informative and balanced it moves the arguments away from the hysteria to a technical one.

His contribution to an event titled ‘LIME – A HOT TOPIC’ run by the Association Conservation of Historic Buildings (ASCHB) in early 2017 led Dr Robyn Pender of ‘Historic England, who Chaired the very well attended evening, to remark that:

  • “Gerard Lynch is a delight on the subject of bricks and mortar: someone who combines deep knowledge and research with an amazing bread of technical knowledge. He was a vital contributor to Historic England’s ‘Practical Building Conservation’ series, notably the ‘Mortars, Renders and Plasters’ and ‘Earth, Brick and Terracotta’ volumes.

  • Speaking, wearing my hat as a committee member of ASCHB, I have more good things to say. Gerard was the glue that kept everything together on ASCHB’s Lime – A Hot Topic’ forum, using his vast knowledge of anecdotal practice to connect the dots between the theories of traditional lime use, and the re-evolving practice. He was a great pleasure to work with too” (July, 2017)

See the Myth In The Mix Article Here

Please click Here to download the Article -  Hot Lime Mortars for Traditionally Constructed Brickwork

Download • 1.33MB

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