Conservation of render and plaster

Lime, lime paints and limewash

A lime-treated façade has its own luster and life. Living with the weather it ages with grace. Lime is a building material with long traditions and is still the best alternative for our old buildings and lime substrates.

Protection of facade and heritage

Correctly applied and maintained, a lime-treated façade can provide good protection against rain and fulfill aesthetic expectations. The lime façade has its own life living with rain, and it develops a natural patina due to strain from water, sun and wind. It is a pure mineral treatment based on lime (dry or wet slaked), damp diffusion open and often pigmented with mineral-based or inorganic pigments. Lime will, when correctly applied with quality and care in all parts of the process, yield the sought protection and at the same time fulfill the building's value as cultural heritage. Lime-based paints are often considered as an additional treatment which protects the underlying layers of renders. When the lime is all worn, it is time to reapply with a new treatment.

Care in all parts of the process

Lime paint

Lime can work on different substrates. The best substrate though is a well-carbonated lime render. NHL-based mixtures and lime-cement mixtures with a high lime ratio are also suitable. The substrate should be repaired with the correct material and prepared to obtain the same suction over the whole surface. Different applying properties (suction, pretreatment, applying method and hardening conditions) might produce colour differences. Depending on the lime product to be used, pretreatment can include products opening the surface pores and after-treatment with limewater to kick-start the carbonation process. A golden rule is to apply several thin applications of lime, followed by spraying with pure water. A final coat of limewater will fix the lime and reduce smitting. As with all works involving lime, protection from fast drying, wetting and frost in the carbonation period is essential to obtain a long-lasting result.

Paints based on hydrated lime are still the most commonly used paint for renovation throughout Europe. Complying with the original material, modern premixed paints, both dry and wet, have shown to be a good match with regards to physical behaviour compared with site-mixed paints. Premixed paints ensure stable quality in terms of colour (traceability of the pigment composition) and lime-to-water ratio. A total control of the binder and mix helps to reduce uncertainty regarding physical behaviour and colour variations, and ensures the durability of the product itself. Different application methods and additives used historically in paint techniques can also be used to regulate its properties and behaviour.