Common Questions

What is Lime?

Firstly, what lime isn't. It's not a magic bullet that will cure all problems, but if used as part of a more holistic approach in the home (adequate ventilation and air flow, correct drainage solutions, breathable insulation etc) it will help save a buildings fabric, prolong that building for many years to come and make for a much nicer living environment. 


Limestone (calcium carbonate), when burnt in a kiln, loses carbon dioxide and becomes quicklime (calcium oxide).


On contact with water, it combines with it, producing great heat to form slaked lime (calcium hydroxide), also called lime putty or pure lime. This gradually takes up carbon dioxide again from the air and changes back to calcium carbonate. This ‘setting’ is called carbonation. Lime putty mixed with a sand and an aggregate makes mortar.


Pure Lime which is also known as:

air lime, because it hardens on exposure to air
fat lime, from its consistency in putty form
non-hydraulic lime, it sets through air and not through water

How Long Have We Been Using Lime?

For more than 7,500 years burnt lime stone has served as the principal cement - or binder -  in mortar, plaster, render, and lime wash. The ancient peoples who inhabited Jerico in the jordan Valley made a plaster from lime and unheated crushed limestone. The plaster was used to cover walls, floors, and hearths in their homes. 


Dating back 6,000 years to the days of ancient Egypt they used a lime/gypsum mix to plaster the pyramids at Giza. Ancient Grecian builders used fine lime plasters in creating the Parthenon and Roman builders used it extensively throughout their empire in their homes and temples.

What are the Key Benefits of Using Lime and Natural Paints?

Healthy - for you, the built environment and the planet

Lime allows for a more comfortable living environment, and coupled with breathable paint, sheep's wool insulation, adequate ventilation, it can help reduce surface condensation and mould growth


No dangerous Volatile Organic Compounds being 'off-gassed' into our homes as solvent based paints and varnishes do.

CO2 emissions in the manufacture of lime are 20% less than for cement.


Carbon neutral: lime, like cement, gives off CO2 (the main greenhouse gas) during its manufacture. However, unlike cement, lime re-absorbs CO2 as it cures. Meaning that the more lime-based products we use in construction, the less CO2 we expel into the atmosphere. 

Lime mortars allow bricks to be recycled as you can clean the bricks, and the old mortar can be re-used as aggregate into new mortar. 


Cement manufacture causes environmental impacts at all stages of the process.


The cement industry is the second largest CO2 emitting industry behind power generation. Globally, cement production contributes to around 5% of all CO2  emissions (source The Economist 2008)


Cement contain dangerous heavy metals which are released into the air on burning. In some circumstances, mainly depending on the origin and the composition of the raw materials used, the high-temperature calcination process of limestone and clay minerals can release in the atmosphere gases and dust rich in volatile heavy metals, a.o, thallium, cadmium and mercury are the most toxic.


Lime is an important part of any ‘natural house’ – as well as timber, straw-bales, clay and earth, all of which are natural, healthy and biodegradable.

For peace of mind AJ Winter has £5,000,000 PLI, and all of our sub-contractors carry their own insurance too

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