Limewash is an ancient, versatile painting technique.

The use of limewash has spanned centuries and continents. From Europe to Asia, Limewash has been used to protect the walls of buildings and bring life to any structure. Limewash is a white or off-white paint made by mixing burnt limestone with water, also known as quicklime. This creates an exothermic reaction that breaks down the lime creating a hot paste that can be used immediately or left to cool and thinned out with more water. It is used for covering exterior and interior walls. Instantly creating a bright white colour, the limewash can also be tinted with natural pigments for various aesthetic alterations.

No wonder limewash is so widely used: it reduces surface cracking, offers protection from water damage, and allows the home or structures underlying fabric to breathe. Its freshness and versatility lend limewash a timeless appeal, perfect for all buildings, from traditional cottages to contemporary condos. Limewash has several other benefits, including being breathable, durable, and eco-friendly.

Limewash has long been the most popular choice for homeowners and building conservators looking to add colour and protection to walls. This is unsurprising as it offers many advantages over other materials. It is an excellent way to protect the substrates of a structure from water damage and cracking while also allowing it to breathe. Limewash is also highly adaptive; its versatile look works just as well on contemporary condos as on traditional cottages. Moreover, compared with other paints or sealers, limewash is very eco-friendly, breathable, and durable – all of which are sure to make this timeless material a favourite of homeowners everywhere.

Limewash prevents rot and allows buildings to breathe.

Limewash has been used as an accompaniment to preserving wood and masonry for centuries. A historic product free from modern additives. Limewash is unique because it offers a permeable barrier that allows water vapour to escape. Limewash prevents rot in structural timbers and erosion to the masonry, which might occur due to trapped moisture or severe weathering. Limewash helps protect against weathering by forming a durable physical barrier against rain, wind and sun. In addition, the breathable material naturally draws out water vapour, which can rot timber or cause erosion in stone and brickwork over time.

Limewash has a long track record as a trusted product, and its exact composition complies with current regulations on moisture-controlling materials. Limewash assists in maintaining the ability of the building to breathe as it is one of the most vapour-permeable decorative coatings. Tests show that limewash has a vapour permeability rating of about 350 units, while many masonry paints are well below that rating. Therefore, limewash is an appropriate choice for Grade I listed buildings, and it’s also extremely popular with homeowners wanting to preserve and enhance their property with attractive natural materials.

Limewash is a natural bug repellent.

Limewash is an increasingly popular solution to the problem of mosquito larvae and bug infestations in timber materials. Woodworms and the deathwatch beetle hate limewash and will avoid it anywhere it has been placed. This simple yet effective process involves spraying or painting a lime-based solution onto surfaces. Its powerful active ingredient, calcium hydroxide, has been proven highly effective at eradicating mosquitoes and other pests from timber. It also acts as a preventive measure, discouraging bug infestations by creating an alkaline surface that deters them from taking hold. Perhaps best, this solution is sustainable and significantly more affordable than many other pest deterrents today. Limewash may be the answer for those searching for an affordable yet impactful defence against bug infestations inside the home.

Calcium hydroxide is a naturally occurring insecticide used for numerous years. Mixing calcium hydroxide powder with water and applying the substance with a sprayer to dormant plants before the growing season offers an effective form of pest control against aphids, flea beetles, Colorado potato beetles and other pests that may hinder the growth of plants. However, it is essential to remember that direct application to foliage or roots could cause burn or destruction due to its corrosive properties. Besides its pesticide, hydrated lime is also employed as a deodorant for organic waste and carrion. This simple substance can prove highly useful when preventing insect damage or camouflaging unpleasant odours.

Limewashing walls helped to prevent the Great Plague from spreading.

In 1665, The Great Plague devastated Europe and caused the death of around 200,000 people over 18 months. However, despite a lack of understanding and technology compared to our day and age, our 17th-century predecessors were surprisingly advanced in their techniques for mitigating the spread of this deadly disease. The successful implementation of social distancing and disinfectants during that period set a precedent that we continue to live by today. One such tool was limewash – a technique synonymous with medieval times and still used in modern building preservation methods – yet one is also highly effective against bacteria due to its high pH level. Scientists experimenting with infused wood and limewash discovered that it is as potent as modern antibacterial sprays! It seems incredible that our ancestors used such sophisticated methods hundreds of years ago.

Limewash is quickly becoming a popular choice of paint amongst many homeowners due to its natural, odourless and non-allergic composition. It also has antibacterial properties, which makes it effective at preventing viruses from spreading, an essential factor in the current climate. Further advantages of this beautiful product include its ability to regulate the humidity levels inside the home. This is because limewash allows water vapour to be drawn through it; this process prevents condensation from forming on walls and ceilings, thus creating a comfortable living environment for all family members. In summary, limewash provides many benefits, and its natural properties could soon be the perfect substitute for modern-day paints.

Limewash is a natural incombustible paint.

In 1212, a disastrous fire swept across the streets of London, which not only burned down many buildings along the Thames but also engulfed much of London bridge. Fortunately for the citizens, the recently refurbished stone structure held firm against the devastating flames. However, all other structures built along the bridge as sources of income were destroyed. In light of this, King John took action amongst shop owners surrounding the London bridge and the Thames that decreed all houses must be covered in plaster within eight days or demolished if they were made up of reed or rush. Additionally, it was declared that all bakeries and breweries should be plastered and limewashed to safeguard them from future disasters.

Fires have always posed a significant threat to our country’s wooden structures. To combat this, many solutions have been employed to coat the wood to make it resistant to fire; alum, lime and clay mixtures have proven the most successful, cost-effective routes. During the era of open fires and timber constructions (reminiscent of medieval Britain), certain precautions needed to be established to minimise the risk of flames. Lime plaster and lime wash were widespread solutions that helped protect homes from burning down.

As a non-flammable and heat-resistant finish, limewash protects buildings from potential fires. This makes limewash suitable for use in areas with fire risk, such as near fireplaces or grills, on walls near furnaces or other sources of intense heat. Limewash can be used in establishments that require the use of fire-retardant materials. For anyone looking for a safe and long-lasting finish for their home or business, limewash paint is an option worth considering. All lime mortars and renders have a classification rating of A1 resistance to fire as outlined in BS EN 13501-1.

The effects of limewash on metal surfaces.

In 1916, an experiment conducted by a U.S. civil engineer uncovered a game-changing discovery – Limewash was found to be an effective preventative measure against rust on iron surfaces. Through submerging parts of iron in slaked lime, rust did not form even after continued exposure to fresh Mississippi river water. Lime has since been found to have no adverse effects on stainless steel and lead. However, it is still important to carefully assess the surface area you plan to paint near or over with a lime-based product, as it can be corrosive to galvanised steel, aluminium and other metals. Truly a revolutionary find for those looking for a protective coating for their iron surfaces!

Compared to concrete, little attention is paid to the corrosion behaviour of metals in contact with lime mortar. This environment is also essential, and its pH decreases over time, but the results indicate important differences in the behaviour of these systems. Carbon steel, passive in concrete, corroded in lime mortar after three months; the corroded layer developed between the metal and adhering mortar. The zinc-coated steel did not rust within the studied time range in the lime environment. Copper formed a Cu-S corrosion product, dispersed in an adjacent layer of mortar, despite being a relatively noble metal. On the other hand, zinc in brass provided passivation to the material, and any corrosion has not been observed. The lead corroded to Pb(OH)2−4 anion dispersed in the lime mortar.

It can be concluded that the best corrosion compatibility with the lime mortar in a wet environment proved brass and zinc-coated steel. Czech Science Foundation project Nr has supported the work. 18-13525S “Modern mosaic mortars in a microscope – methods for their materials characterisation and degradation studies”.

How to make limewash at home.

Painting walls using quicklime is an old handcraft used by many ancient civilisations and can bring a unique quality to your home. Firstly, you’ll need to purchase quicklime from a lime supplier: burnt limestone or calcium oxide. Quicklime products can be dangerous, so it’s imperative that when handling them, you wear the proper PPE – goggles, mask and gloves – as well as ensure your arms and legs are covered.

To prepare for the application, fill a metal or rubber bucket about three-quarters of the way with water and use a metal scoop to slowly add quicklime powder into the liquid, gradually mixing with a chopped-down wooden broom handle until the water boils and the paste thickens. Getting the consistency right takes practice but typically involves little dripping from brushes when appropriately mixed. For those new to this craft, however, being informed of these steps beforehand is essential for a successful outcome.

Where can limewash be used on a building?

Limewash can be used for more than just painting traditional interior and exterior walls. As well as providing beautiful colour, it has many other benefits in preserving wood, preventing pest infestations, neutralising odours and regulating moisture levels. One great use of limewash is on wooden windows, structural timbers and floor joists; it helps draw out moisture preventing the wood from rotting. Limewashing such timbers make them less susceptible to bug infestations like woodworm or deathwatch beetle. Limewash can also help regulate the moisture levels in cellars or basements with the correct ventilation. The antifungal properties in limewash also help to prevent mould development on subfloor walls. An outhouse was commonly limewashed in the past due to its natural antibacterial qualities and effective odour neutralisation.

We recommend watching an excellent lecture from the Historic England IHBC Conference on the topic of the role of lime mortars and coatings in dissipating moisture. Please find it here.

Maintaining limewash is simple.

Limewash is a unique and stunning way to decorate walls, providing an elegant, mottled, shadowy effect. This eye-catching decoration is also low maintenance, requiring no more than a simple re-coat should the wall need a touch-up. Cleaning limewashed walls is not recommended, as it detracts from the look of the wall and can leave marks where the paint has been worn away; unlike standard painted surfaces, dirt does not show up as quickly on limewashed walls. Therefore, a mild re-coating of the wall periodically results in the best and most beautiful outcome.

Limewashing is an excellent choice for external walls of buildings since it’s highly durable and can be applied in many colours and styles. The need for doing this may vary depending on the building’s location and exposure levels, but a limewash can last 5-10 years before needing a new coat. If a building is located in an area with more extreme weather, more frequent limewashing may be necessary due to the elements breaking down the coating more quickly. Limewashes are preferred by many homeowners who want to ensure their building’s walls remain protected over time compared to traditional paints that may not have as long of a life span when exposed to similar environmental conditions.