Click on the links below to jump to the appropriate limewash guidelines.
- Limewashing on new lime renders or lime plasters
- Limewashing over old coats of limewash
- Limewashing onto masonry & emulsion paints
Limewashing on New Lime Render or Lime Plaster
Limewash is a very traditional decorating product which allows the structure to “breathe” – allowing any moisture present to evaporate away rather than be trapped in the wall. Limewash has a matt finish and helps consolidate and improve the surface of both old and new plaster both physically and visually. Because limewash is a porous paint, it shades in depth of colour to reflect the dampness of the background material.
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 quicklime. It will develop a fine finish over several coats; we recommend a minimum of 3-4 coats on new render and plaster.
Mike Wye 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. ACS Mould Wash Concentrate) which should be rinsed off before limewashing.
Damping
Damping is very important for 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 to prevents the water in the limewash from being drawn out too quickly on application.
First Coat
Whisk the limewash thoroughly before use.
Brush apply limewash with a large emulsion or masonry brush. Don’t let limewash 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 limewash dries to a much lighter shade than the wet colour.
Subsequent Coats
4 coats are recommended on new external lime render; 3 coats on new internal lime plaster.
Ideally leave each coat to cure for 24 hours. For each further coat, follow the same procedure as the first coat.
Protect external limewash from the weather if necessary. A thin coat curing slowly in the presence of moisture will form a more crystalline, hard-wearing surface compared to a chalky finish if a thick coat dries out too quickly.
Frost
Limewash is a water-based paint and therefore shouldn’t be applied in temperatures less than 5 ºC 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 decorated.
Safety
Limewash is 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.
Limewashing Over Old Coats of Limewash
Further to the general guidance above,”Using Limewash on New Lime Render or Lime Plaster”, we would suggest the following points are noted:
- Remove flaking limewash with a stiff brush to get rid of loose material. Dampen the wall down with clean water before application of each coat.
- Apply a thin coat of limewash. Mike Wye make a relatively thick limewash so don’t be tempted to apply thicker coats.
- Ideally leave each coat to cure for 24 hours. For any further coats, follow the same procedure.
- Protect external limewash from the weather if necessary. A thin coat curing slowly in the presence of moisture will form a more crystalline, hard-wearing surface compared to a chalky finish if a thick coat dries out too quickly.
- If adding casein into a limewash (for improved bond), mix the casein with some warm water first. Always add water to powder and slowly whisk to form a paste and leave to stand for 30 minutes. Slowly whisk in more water until a similar consistency as the limewash is achieved. Leave to stand for a further 15 minutes and then whisk well into the limewash.
Poor bonding of a new limewash onto an existing limewash can result from:
- Additives in the original limewash such as tallow or raw linseed oil, which reduce the porosity and hence the key for the new limewash.
- Surface dusting or chalking, which may detract from a sufficiently consolidated surface for the new paint to key onto.
- Applying the new limewash too thickly. Our limewash is already relatively thick and easy to apply with or without added casein and must be applied thinly.
- Rapid drying caused by insufficient damping down prior to application or insufficient control of the drying process (e.g. by spraying or physical protection).
- Applying in low temperatures or when there’s a risk of frost.
- Over-enthusiastic application of water before application of lime or application of lime too soon after damping down as this stops the suction.
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.
Limewashing on Masonry or Emulsion Paint
Further to the general guidance above “Using Limewash on New Lime Render or Lime Plaster”, we suggest the following points are noted:
- It is difficult to limewash onto surfaces painted with masonry or vinyl emulsion paint and is always best remove other types of paint before limewashing. There are a number of factors to be considered:
- Preparation is very important. 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 decorating.
- The previous paint system may not be very porous, therefore the benefits of the limewash will be aesthetic rather than functional. Because the background material isn’t necessarily porous the limewash isn’t able to soak in to the material. Instead it will tend to sit on the surface. This will make it prone to flaking or weathering at a faster rate than usual. This can be very rapid in some cases.
- A sample area should be tested to judge adhesion of the limewash, the ease of painting and the degree of coverage achievable with two or three coats.
- It may be necessary to add ingredients to the limewash to improve its adhesion and durability. Traditionally both casein (from skimmed milk) and common salt have been added. There are also a number of old recipes using various sources of albumin, such as egg white, milk, blood and plant seeds. Albumin is a simple protein that combines with slaked lime to produce hardening properties. We have used and supplied a casein paint as an additive at the rate of 250 g of casein paint to 10 litres of limewash. If adding casein into a limewash, mix the casein with some warm water first. Always add water to powder and slowly whisk to form a paste and leave to stand for 30 minutes. Slowly whisk in more water until a similar consistency as the limewash is achieved. Leave to stand for a further 15 minutes and then whisk well into the limewash.