The Building Limes Forum

Conference and Annual Gathering Lincoln, England-September 1-3, 2023
Jeremy Mistretta
September 14, 2023
8 min read

Calcium Carbonate, or “lime” has a myriad of uses in our world.  Its origins date back thousands of years, and we suspect that early cavemen broke off chunks of limestone around a fire pit and with the addition of water, the “quicklime” became hydrated lime or lime putty.  The resulting binder was then mixed with an aggregate such as sand.  During the drying stage, the mortar or plaster absorbs free carbon from the air and reverts to limestone.  Since the inception of caveman time, this chemical compound has been integrated into air systems, wastewater management, agricultural development, and of course construction.


I have been entrenched in the building trades since I was 16 years old and first picked up a trowel in 2003. Twenty years later, I’m still upside down in love with the industry.  It’s fast paced, challenging, and rewarding.  Having earned the opportunity to apply lime inside some of the nicest homes on the planet gives me great joy.  While many of them are large, and the installations at times arduous, I’m pleased that we’re making the walls beautiful.  And more importantly, I am pleased that we are using our own handmade products to do so.  I don’t think that we’ll ever get to carbon neutral with home construction, however I do think that every bit of viable effort helps to bring our footprint down.  The high embodied energy of concrete, the waste of remnant gypsum, and the softness of clay make lime plaster an easy choice for the conscious modern plasterer.

The internet is a powerful tool in the world of construction and often a crowded space of information.  Through research and design, I had often stumbled upon the BUILDING LIMES FORUM.  It’s a rich source of information in an online format and it prints frequent copies of their journal.  The organization encourages the expertise and understanding in the use of building limes.

Through thorough and informative articles, I’ve been educated on traditional lathe and plaster construction and repair while being entrenched in capillary water absorption in blended mortars.  Each journal stands alone as a work of art in itself, and the website covers pertinent information about where to purchase lime in your area, trusted contractors, and newsworthy projects.  It’s an encouraging platform with members and chapters across Europe, North American, Asia, and Australia.

With a timely trip to the United Kingdom to film two new artists for our online platform I was able to attend the annual 2023 gathering.  This year it was held in Lincolnshire with the theme of “Simplicity, Quality, and Modernity:  A Legacy of Lime.”  It was a jam packed 3-day event full of lectures, tours, and skill demonstrations with participation from energetic delegates around the globe.  

Day 1 began with a host of scintillating lectures to a crowd, thirsty for information.  Philip Gaches gave a superb mortar analysis presentation of lime and aggregates from projects that were hundreds of years old.  It was interesting to see the size of aggregate in relation to the binding hair that was used for tensile strength.  In sharp contrast to the English limes of the 17th and 18th century, Emilija Nikolic from the Institute of Archaeology in Serbia educated us on Roman mortars from The Danube. We all enjoyed her slide show that included cross sections of her samples, varied aggregates, buried archeologic trowel finds, and photos of impressions that were found in the bedrock from ropes used to haul stone.

The afternoon sessions consisted of live workshops that highlighted not only locations, but also artists and their skillsets that celebrated time honored techniques.  Eagerly, I attended the skills demonstration with Brian Tobin, a fellow plasterer and new friend from Ireland.  I first met Brian at a workshop in Southern France in late 2022 and was elated to see him again.  Brian’s company specializes in the restoration and care of historic buildings in and around Ireland.  He was just as enthusiastic about the skills demonstrations as I.

The afternoon was spent enthralled with the demonstrations and Brian’s Irish accent and witty sense of humor.  We laughed together with Rebecca Gilling as she expertly sculpted an ornate leaf from an inspirational original enrichment from Ashby Hall in Lincolnshire.

We also sat in awe as Rachael Wragg, aka @thegingermason demonstrated her skillset of stone carving.  Rachel has been working diligently as a stone mason at The Lincoln Cathedral for the past 5 years.  She began her apprenticeship in 2018 and was kept on as an active mason.  “I was very lucky,” Rachel told us.  After seeing her skillset on display, it was evident that “luck” had nothing to do with the cathedral’s employment decision.  Her work was deliberate and precise, and executed with a kind smile. As she skillfully chiseled the center of a piece of stone, she discussed her workdays with us and sadly mentioned that there is only about 10 years of authentic limestone left in the area for conservation.

The cathedral is actively searching for more.  If they can’t find more in the area, it’s likely that they will resolve to the use of a nearby French Limestone that is similar in look, but not density.

After the sculpture and masonry sessions, we retreated outdoors to meet with the energetic Nigel Copsey.  Nigel is a world-class expert in lime and is the proud author of “Hot mixed Lime and Traditional Mortars.”  Nigel excitedly educated the class on his theories of lime slaking and hydraulic vs non-hydraulic limes.  He posits that “hot slaking” (a technique of adding calculated amounts of water to quicklime and sand) produces the same if not better result than using conventional lime putties. His passion is real and his techniques have been field tested.

While some of the delegates professionally disagreed with his approach, the group respected him and his knowledge, and his desire to share field findings.

After a restful night’s sleep, the delegates happily returned on DAY 2 for more knowledge.  Maria Stefanidou from Greece discussed comparative studies of lime putty, dry hydrates and quicklime mortars, while an exuberant David Wiggins from Scotland enthusiastically discussed his field studies of carbonate binders in wet environments.