Lime-based products are rightly popular for their sustainable nature and exceptional breathability. At EWI Pro, we currently house a Lime Render and Lime Basecoat. However, there are many other lime products that mesh exceptionally well with heritage restoration. Two of those are Lime Paint and Lime Wash, which are used to cover walls internally or externally. The base ingredient for Lime Paint and Lime Wash is naturally limestone, however, the processing is different to the creation of a render or basecoat. A paint or wash will come premixed as opposed to a dry mix.

What is Lime Paint?

Lime paint is one of the oldest known natural paints. It is traditionally made from limestone that has been converted through a burning and slaking process. Limestone (calcium carbonate) is initially heated at high temperatures to produce quicklime (calcium oxide). This quicklime is then carefully mixed with water, a process known as slaking, resulting in slaked lime or calcium hydroxide. It transforms into lime paint when mixed with natural pigments and further diluted with water.

Environmental and health benefits

One of the compelling reasons to choose lime paint relates to its ecological and health advantages:

• Low Carbon Footprint: Lime paint inherently absorbs carbon dioxide during curing, which can help reduce a building project’s carbon footprint.
• Non-toxic: Since lime paint is made from natural ingredients, it does not contain volatile organic compounds (VOCs) or other toxic additives commonly found in synthetic paints, making it safer for the environment and indoor air quality.
• Natural Antimicrobial Properties: Lime paint’s high alkalinity makes it naturally resistant to mould, mildew, and bacteria, promoting healthier living environments.

Aesthetic qualities

Lime paint is celebrated for its unique visual qualities that improve with age:

• Matte, Velvety Finish: It offers a matte finish with a velvety texture, quite different from the gloss or semi-gloss finishes typical of acrylic or oil-based paints.
• Depth of Colour: Lime paint interacts uniquely with light, giving a soft, luminous effect that adds depth and texture. This interaction also means that the colour can subtly change depending on the lighting conditions.
• Colour Variation: Each mix can produce slight variations in shade, enhancing a wall’s character with a more organic and dynamic feel.

What is Lime Wash?

Lime wash is derived from limestone that is burned to create quicklime, then water is added to slake it, resulting in hydrated lime (calcium hydroxide). This slaked lime is mixed with water to form a lime wash, and a breathable coating penetrating the substrate is applied. Pigments can be added to the wash to achieve various colours, although the traditional lime wash is a brilliant white.

Environmental and health benefits

Lime wash is an environmentally friendly and healthy option for building finishes:

• Sustainable: Lime wash is made from natural materials and is fully biodegradable. It also helps in carbon sequestration, absorbing carbon dioxide from the atmosphere during curing.
• Non-toxic: Free from solvents and other volatile organic compounds (VOCs), lime wash creates a safe indoor environment and prevents the health risks associated with many synthetic paints.
• Natural Antifungal Properties: The high alkalinity of lime wash acts as a natural fungicide and bactericide, which means it can help prevent the growth of mould, mildew, and harmful bacteria on surfaces.

Aesthetic qualities

Lime wash creates a distinctive look that is much sought after for its aesthetic:

• Textured Finish: Lime wash provides a matte, textured finish ranging from smooth and uniform to mottled and streaked, depending on the application technique.
• Colour Depth: Over time, lime wash weathers to a pleasing patina that many find desirable. The gradual weathering and fading of the colour can add character and depth to a building’s appearance.
• Light Reflectivity: The crystalline structure of lime wash interacts with light to give it a subtle luminosity, enhancing its natural beauty.

Lime paint and wash are ideal for historical buildings where maintaining architectural integrity is essential. They are also increasingly used in eco-friendly and green building projects because of their low environmental impact and contribution to healthy living spaces. However, it’s important to note that lime paint and wash are best suited for materials that are naturally porous and breathable; they are less effective on non-porous or previously treated surfaces where they cannot bond properly.