By Paul Watts

Generally limewash should be applied thinly and be allowed to dry out slowly. Our limewash is prepared from the finest quality lime putty slaked from Buxton quicklime. It will develop a fine finish over several coats, we recommend a minimum of four on new render and plaster. Supplied in a huge range of colours, our limewash has a small quantity of linseed oil added to reduce "dusting" and improve external water shedding. Historically, many ingredients were added to limewashes to modify their performance such as common salt, casein, tallow and linseed oil.

 

Preparation

 

The surface to be limewashed should be brushed and washed free of any loose particles, dust, dirt, lichen etc. If there is mould growth the surface should be treated with a fungicide (e.g. a weak bleach solution) which should be rinsed off before limewashing. Old coats of limewash can be cleaned with a solution of citric acid crystals.

Damping

 

It is very important to damp dry surfaces but may not be necessary if limewashing new lime render or lime plaster which has yet to totally dry out. Spray the area before limewashing with water as this prevents the water in the limewash from being sucked out too quickly on application. The water must be allowed to suck into the substrate or the limewash may fail after a week or so.

 

 

First Coat

 

Whisk the limewash thoroughly before use as the putty will settle out. Using a large emulsion brush or paint pad apply the limewash onto the dampened area. Work it well into any cracks or joints but don't let it build up too thickly as it can craze on drying out. Remember it's a wash and will look transparent on application but will dry opaque. Coloured limewashes dry to a much lighter shade than the wet limewash.

 

Subsequent coats

Four or five coats are recommended on new external lime render, three coats on new internal lime plaster. Ideally leave each coat to cure for a minimum of a day. For each further coat, follow the same procedure of misting well before limewashing and allowing to dry out slowly, with light spraying if necessary. Protect external limewash from the weather if necessary. A thin coat curing slowly in the presence of moisture will form a more crystalline, hardwearing surface compared to a chalky finish if a thick coat dries out too quickly. After the initial carbonation and curing limewash will continue to strengthen for several weeks.

 

 

Frost

 

As limewash is a water-based paint, it shouldn't be applied in low temperatures of less than 5ºC or if there's a risk of frost.

 

Quantities

A litre of limewash will cover 3 - 6 square metres for one coat, depending on the smoothness and porosity of the surface being limewashed. 

 

Safety:

Limes are caustic. Always wear eye protection and protective gloves and clothing and follow the safety instructions on the labels. Our advice and information are given in good faith. It's important that users satisfy themselves that they've chosen an appropriate product and have a suitably skilled workforce.

 

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