Do not assume every mortar was created from a hot lime mix

We need to remember that within the current fashion for recreating hot lime mortars that in many areas historically the burnt lime was very difficult to use in such a way.

Just back from helping crafts people and specifiers in northern Ethiopia develop their skills and understanding of traditional plasters, Mark Womersley watched and worked with local people to prepare lime renders and plasters.

The burnt limestone currently used has a high iron content and when tested is naturally hydraulic but without the crushing equipment and the ability to slake using steam much of the burnt lime remains as large lumps of un-slaked material when water is added to it. Often two thirds of the content of each batch of quicklime has to be discarded as it remains un-slaked.

The slaked material runs into pits as a slurry and needs to be left for 6 months to 10 years to mature into a lime putty with sufficient concentration of calcium hydroxide within it to be affective as a binder.

The tradition in this part of Ethiopia at least in more recent times crushes by hand this waste material to make an aggregate, providing mixes of a very high lime content that give the appearance when set of a hot lime mix. But this is false.

These mixes provide a very good set over longer periods of time and have in recent years been used to create limecrete domes and waterproof swimming pool lining plaster. This area of Ethiopia receives up to 1 metre of rain fall per month in the wet season and the mortars are tested with this onslaught.

The mix appears to create a hydraulic mortar that gains strength over time and forms a very durable material.

Slaking lime into a pit

Specifiers learning from crafts people how to crush the unslaked lime to use as an aggregate

The early 17th Century Fasil Bath lined with lime rich feebly hydraulic plaster

A dome recreated with unslaked lime aggregate 30mm down and slaked lime from mature pits

 

Go back

2018
Day 6: Promoting Tourism through Conserving Heritage Conference Final day in Ethiopia Conservation Management Plans and Goodbye Day 4 Lime Training in Ethiopia Day 5 Lime Training in Ethiopia Day 3 Training in Ethiopia Day 2 of Lime Training in Ethiopia Empress Mentewab's Kuskuam Complex Lime Training in the Royal Compound at Gonder Day 1 of Running Lime Training in Ethiopia Conservation at Guzara Palace Earth mortars and Northern Ethiopia Inspirational Wattle and Daub in Ethiopia Providing Lime Training Out of the Rain An introduction to Silicate Paints Natural Pozzolana described by Vitruvius in the Roman Era Faux Marbling and Traditional Paints Training test Spenfield House Decoration Inspires Training Day Training at the Jewellery Quarter Birmingham Lime render finish coats for innovative design Paint Stripping Samples for Wythenshaw Hall A refresher day on Hot Limes for Mono Masonry Cast Roman Cement from 1840 on a building in Liverpool The colour is great and lots of very positive comments Fiona's Sheep formed from Womersleys Stone Repair Traditional Stand Oil Paint on new garden gate Tithe Barn now finished after Womersleys supply foamed glass insulated floor Ryedale Plasterers honing their skills & techniques Stone and Brick Repairs We would love to see you at Harrogate free tickets are available here Womersleys Insulating Lime Render Plaster and Moisture Buffering New Wattle and Daub supplied by Womersleys Ordsall Chord is coming to a successful finish Oil Paints and Distempers used to create an Illusion The iron rich limestone and aggregates of south east Sicily Marbeleizing with Natural Oil Paints Lime Mortars have always had to with stand extreme weather and seas The Cathedral Church of Saint Nicolo presents a fine Baroque façade The beautiful Noto limestone cladding Noto's Baroque Buildings Beautifully weathered lime render Lime stucco repairs to capitals Brick and Stone Formwork Exposed behind Lime Stucco Render Historic Lime Kiln at Shap Lime Stucco Work by Giovanni Bagutti Plaster, Daub and Render Survey at Old Hall Farm Repairing clay daub and lime plaster on panels of riven lath and insulating externally with insulated lime renders Use of mobile elevated platforms in Theatres Creating Formwork and Constructing an Arch An introduction to Lead Work Training Day Working with volunteers on the Chesterfield Canal Helping the Canal and River Trust Volunteers Training Course Sicily Building Kiln Training Course Sicily: Chuch of San Nicola Womersleys training course Sicily It really is as beautiful as they say Traditional buidling techniques Garden Corner Tower circa 1650, Agra Living Heritage Real Market Places Fine polished lime plaster ensured opulent splendour Indian Mortar Mill India Gate Lotus Flower forming 17th Century Column Bases Seventeenth Century Chrysanthemum Detail The Lotus Flower and the Indian Flag 17th Century Lime Stucco on brick Seventeenth Century Indian Frescoed Lime Stucco RIBA accredited CPD paint seminars Ceiling Survey Reveals a Glimpse of Former Decorative Glory Clay Infill found in Exeter's Grand Royal Clarence Hotel Foamit Sub Base for Great Tythe Barn
2016
Get your free tickets for the National Home Building Show Understanding Marple Lime Kilns It would be good to see you Sensitive refurb planned for Forge Cottage Last of Five Days at Grand Designs promoting Womersleys Stabilising a boundary wall with Hydraulic Hot Lime Mortar Its nice to be appreciated Training with Help the Heroes Volunteers The historical development of a simple wall Trialling hot lime mortar Lime Mortar Training Yesterday at Womersley's Breathable and natural paints for Lighthouse Aglaia emulsions used at St Leonard's Latest build by Guy and Straw Works Ltd Advice on Breathable Insulation for a Windmill More Lime Wash for West Wycombe Park Our latest article in the Listed Heritage Magazine Toft Gate Lime Kiln in Nidderdale The whole is greater than the sum of its parts What a pleasure to be booked in to resurvey the Apollo Tim's Nidderdale Dream Womersleys helping with Conservation Skills Training Programme Lovely Chamfers Working with our German Paint Partners The Ceiling Centre Tells a Story Historic Mortar Analysis for North Bar, Beverley New Foamed Glass Sub Base for Beamish Park Gardens Refurbishment Plasterwork survey at Oakwell Hall Completed Please call in to see us if you are at the Great Yorkshire Show Renovation in the Prettiest Village in the County Offering Paint Advice at Holy Trinity Church, Hull Developing Thornton's Conservation Area Assessment to Guide Develeopment Talbot Yard Malton Wins Award Insulating an Old Building with the Internal Warmshell System The Hairy Builder (Biker) Promo Traditional and Natural Paints featured in LPOC magazine Results of Plaster Survey at Wythenshaw Hall following fire damage New pre mixed Ironstone mortars introduced Results of Plaster Analysis at Castle Dairy Kendal Womersleys continue to supply lime mortars to Pontefract Castle Plaster Survey at Wythenshaw Hall following fire damage Holy Trinity Church Sunderland Plaster Survey Investigations in to the condition of the plaster on the walls at the Exchequer Building, Palace Green Library, Durham Plaster Analysis at Castle Dairy Kendal Free Illustrated Case Studies detailing Insulated Floors for Old Buildings