What is Limewash?
Limewash is a very ancient paint made from limestone which has been crushed, burnt and slaked with water to make lime putty. The lime putty is matured for several months before being thinned with water to make limewash.
Limewash is naturally white and forms a complex crystalline matrix which has a matt, slightly chalky appearance. It is coloured with pigments and can be used internally or externally where it works best on porous surfaces such as a traditional lime plaster, lime render, stone and brick. Unlike modern barrier paints, limewash works by sinking into the surface. It hardens by absorbing carbon dioxide from the atmosphere to form crystals of calcium carbonate which give the limewash its deep matt appearance and protective qualities. When used on porous surfaces, the colour will deepen if there is any dampness in the background material, hence its attractive shading.
Tallow (animal fat) or raw linseed oil are traditional additives which help to improve its water-shedding qualities when used externally.
As it is a water-based paint, limewash isn’t easily absorbed into less porous surfaces such as cement renders or hard gypsum plasters, and therefore it won’t wear nearly as well on these. Additives such as casein (skimmed milk) can be added to help it bond to these less porous materials.
Further details of our limewash, including prices, can be viewed on the Limewash Product Page.
The benefits of limewash
The way older dwellings are built affects the best way to repair and decorate them. Old buildings were traditionally of solid wall construction, rendered with breathable lime mortars and limewashed. These materials reduce the effects of condensation and allow the moisture in the walls to evaporate to the outside. Misguidedly trying to seal the weather out of traditional structures can lead to dampness, rot and condensation problems, causing decay in structural timbers and damage to the cob and stone walls themselves.
Being alkaline, limewash is anti-bacterial and insecticidal (woodworm and death-watch beetle hate it) – hence its wide usage on farm buildings. It also has fireproofing qualities – all the houses on the Thames were lime plastered and whitewashed after the great fire of 1212 as a precautionary measure.
Our limewash naturally comes as white but we also offer a large range that is coloured with both Natural and Manufactured pigments. The natural pigments are clay and silica, coloured with iron oxides in the earth. They are mined all over the world but some take their names from their primary locations – Sienna, and Umbria for instance. Natural pigments have less colouring intensity than manufactured pigments which are produced mainly from iron oxides to replicate traditional earth pigments. These are much stronger in hue, consistent and very durable.
This chart illustrates our range of traditional limewash colours, but we also provide a colour matching service for a fee of £40+VAT. The colours shown are a close approximation, not an exact match. 100 ml samples of the limewash are available for £2.20+VAT plus postage and packing.