Dusty Surface
How do I fix a dusty lime wash paint surface that rubs off easily?
My lime wash finish is dusty and the paint is rubbing off - what can I do?
There are two reasons why a lime wash finish may turn our dusty or the paint comes off easily when the surface is touched.
In all cases natural, mineral based lime wash, such as from Bauwerk Colour, requires a moderately absorbent surface. Where a surface is non-absorbent or absorbs too little it is necessary to create the right surface that the lime wash paint can penetrate into.
Reason 1 - Lime wash was applied to thickly
Lime wash paint should be applied nice and thin. The rule is to apply rather one more coat thinly than a reduced number of coats too thickly.
The reason for thin coats lies in the better absorption of CO2 and the better crystallisation of the lime wash. This process can take up to 2 weeks, even though the surface is touch dry.
In other words, the surface of the lime wash paint hardens with time and is strengthened with each new coat when time is given for that process.
Reason 2 - Lime wash surface was not prepared properly
As explained above, lime wash paint needs an absorbent surface to penetrate into. For very low or non-absorbing surfaces, such as an underlying acrylic paint surface, or a surface prepared with a Primer, it is best to create that absorbency either with the help of Bauwerk Prep Coat (used only on internal areas) or by applying a fresh cement based absorbent thin coat render (used externally or internally) that will create a surface for lime wash paint to penetrate into.
What can be done when my limewash finish has turned out dusty or the paint is rubbing off?
If the paint was applied to an absorbent surface and was just applied too thickly in most instances it can be rescued with another, very quickly applied lime wash paint coat.
Do not overwork the surface and don't be too concerned if you miss the odd little spot or two. Stretch out the paint and at the same time ensure you work wet in wet.
If the issue was that the lime paint was applied over a non-absorbent surface then we need to establish a suitable absorbent surface for either:
Internal Surface
by applying Bauwerk Colour Prep Coat (please follow the application advice)
or
External Surface
by applying a new cement based absorbent thin coat render (used externally or internally) or a similar product (there are different products int he markets for different countries).
Follow the manufacturers instructions and / or do a sample panel to be able to judge the final result.