I have heard you can add salt into limewash to improve performance is this correct?

I have heard you can add salt into limewash to improve performance is this correct?

Historically salt was occasionally added into limewashes, often in tallow limewashes to assist the emulsification of the tallow. As the salt is hygroscopic it can also aid the carbonation of the lime on exposure.

These salt mixes are not recommended for historic fabric as they introduce unwelcome soluble salt crystallization cycles and these mixes have poorer adherence.

For more information refer to John Ashurst’s book, Conservation of Building and Decorative Stone.