Making and Applying Limewash

In this case study, Michael Lawson (Heritage Painter and Decorator) and Nicky Richards (Apprentice Heritage Painter and Decorator) describe how they make and apply limewash - a surface finish made of lime and water - at the Port Arthur Historic Site.

This case study supports the development of heritage trade skills in Tasmania. It is part of a broader set of support materials that have been developed by the Tasmanian Building and Construction Industry Training Board (TBCITB).

Special thanks to Marty Passingham, Michael Lawson, Nicky Richards and the Port Arthur Historic Site Management Authority (PAHSMA).

Want to learn this heritage trade skill?

If you are interested in learning how to make and apply limewash, contact the TBCITB to register your interest in a training course.

Context

Michael and Nicky are finishing a limewash application on an exterior wall of the Visiting Magistrate's House at the Port Arthur Historic Site.

Two men sitting

Michael and Nicky at the Visiting Magistrate's House

Two men working

Mixing limewash before use

Advantages

There are three key advantages of using limewash as a surface finish:

  • It is a breathable product, which allows dampness to evaporate and not become trapped in the wall (causing problems down the track).
  • You can make it yourself.
  • It is easy to apply.
Man standing next to building

Preparing to limewash

Preparing a surface for limewash

Preparing a surface for limewash

Challenges

There are four main challenges associated with using limewash:

  • You have to slake and store lime well in advance.
  • If it is mixed or applied too thickly, it may crack when it dries.
  • It doesn't apply well in hot dry conditions.
  • It can be difficult to colour match.
Slaking lime

Slaking lime at the Works Depot

Preparing to colour match limewash

Preparing to colour match limewash

Solutions

There are a few handy "tricks of the trade" when using limewash:

  • Always try to apply limewash in cool damp conditions
  • Always spray the surface beforehand, during and afterwards with a fine mist of water from a water sprayer
  • Protect exposed surfaces with shade cloth in hot dry conditions
  • When matching new limewash to an existing colour, make a small test batch, apply it to a piece of cardboard and hold the cardboard against the surface for a visual (side-by-side) comparison.
Bucket of limewash

Colour matching the limewash

Applying limewash

Colour matching the limewash

Steps Involved

Step 1

Step 1 - Slaking lime

  • Wear protective clothing and safety goggles.
  • Assemble materials and equipment.
  • Half fill a solid metal drum with hot water. 
  • Carefully add rock lime to the water.
  • Stir occasionally with a shovel.
  • Add water to thin the slaked lime (as required).
  • Pour through a fine filter into an appropriate storage drum.
  • Label and date the storage drum.
  • Allow slaked lime to stand (approximately three months) before use.
Image for Step 1 - Slaking lime

Adding rock lime to water

Step 2

Step 2 - Making limewash

  • Filter slaked lime through a wire sieve to remove solid particles.
  • Add water and dilute until milk-like consistency is obtained.
  • If colour is needed, dilute powder pigment in hot water.
  • Gradually add diluted pigment to white limewash and visually match to surface colour.
  • Wear protective clothing and safety goggles Assemble materials and equipment.
  • Half fill a solid metal drum with hot water Carefully add rock lime to the water.
  • Mix limewash until it drips freely.
  • Pour limewash through a fine filter into a suitable paint bucket.
Image for Step 2 - Making limewash

Mixing limewash at the Works Depot

Step 3

Step 3 - Preparing surfaces for limewash

  • Treat mould growth with a fungicide (if required).
  • Point deep holes in advance with lime mortar (if required).
  • Poultice surfaces to reduce salt contamination (if required).
  • Scrape and brush surface to remove dust, dirt and any flaking paint (including old limewash).
  • Touch up blemishes and marks (noting these can often be an integral part of the history of a place).
  • Damp down surface with a fine mist of water from a water sprayer.
Image for Step 3 - Preparing surfaces for limewash

Preparing a wall at the Visiting Magistrate's House

Step 4

Step 4 - Applying limewash

  • Damp down surface before, during and after limewash application.
  • Apply limewash thinly with a suitable brush.
  • Work into all cracks and crevices.
  • Do not allow the limewash to build up too thickly as you apply it, or it may crack when it dries.
  • Allow to dry completely (at least one day) before applying next coat Apply at least three coats for a reasonable coverage.
Image for Step 4 - Applying limewash

Applying limewash to a wall at the Visiting Magistrate's House

Result

Always look for a strong finish that does not brush off on clothes.

Limewashed wall before

Before

Limewashed wall after

After