Fixing Powdery Limewash Surface
Learn why limewash sometimes feels powdery or rubs off — and how to fix it and prevent it from happening again
Words
© Andreas Riedel
Published
2024.09
Q. Why is my limewash finish powdery and rubbing off on my hands?
Powdering usually occurs when limewash paint is applied too thickly, preventing it from curing properly. This causes the lime to ‘bloom’ on the surface, leaving white patches and making it powdery, so it comes off easily when touched. For best results, apply limewash in thin coats using a proper bristle brush for limewash application. Spread the paint out as far as it will go, without overworking it. Curing takes about two weeks, so avoid rubbing the walls during this time to prevent marking.
Mineral-based limewash, like Bauwerk Colour, requires a moderately absorbent surface. When a surface is non-absorbent or absorbs too little, proper preparation must be undertaken to create the right conditions for the limewash paint to penetrate. If painting over a sealed or non-absorbent surface, such as a wall previously painted with standard acrylic house paints, lime blooming is more likely to occur, as it is more difficult to avoid over-application of limewash. We recommend using Bauwerk Prep Coat as an important step in surface preparation when limewashing previously painted or sealed interior wall surfaces. For external surfaces that have already been painted or sealed, we recommend applying a fresh cement-based absorbent cement based thin coat render (used externally or internally) to create a surface for lime wash paint to penetrate into.
Note
It is best to reapply Prep Coat if you have already done 4 or more coats of limewash paint.
4 Common Causes for a Powdery Limewash Finish
01
Over application, too much paint applied.
Powdering usually occurs when paint is too thickly applied. The best results are achieved using thin applications rather than thick coats. Bauwerk Limewash cures by taking carbon dioxide from the air, a truly wonderful and natural occurring process. The thin coats allows the right amount of curing. If the paint is too thick, then the paint cannot cure correctly and it leaves white patches and makes it powdery to the touch. This can be easily fixed by waiting 24 hours and then applying another thin coat.
Note: It is best to go back and reapply Prep Coat if you have already done 4 or more coats of limewash paint.
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02
Incorrect Brush
Using a natural fibre brush for limewash application will help to leave minimal brush marks and give the most even finish. It is absorbent and holds a good amount of paint. You may get away with using a conventional brush on a nice absorbent substrate but you will use much more product than needed. Using a conventional brush on a sealed or Prep-Coated surface will give a very poor looking finish.
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03
Bauwerk Prep Coat not used
Bauwerk Prep Coat creates an absorbent surface for the Limewash to adhere to on the wall, we have specially developed our Prep Coat as a bridge coat between standard paint and primers to make limewash more durable, and easy to apply. (For interior use only.) Bauwerk Prep Coat is not a primer. It is important to understand that Bauwerk Limewash and Prep Coat have no capacity to mask what is on your wall, it allows all the history and the materials of the wall to come through.
Tip: Apply a nice even coat of Bauwerk Prep Coat for a consistent finish, Prep Coat can be sprayed on or rolled on and cut in with a brush. Ensure that you cut in while the rolled surface is still wet, working wet in wet and blending the brush and rolled areas will help to avoid a picture framing effect.
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04
Bauwerk Prep Coat applied inconsistently
It is important to apply a consistent coat of Bauwerk Prep Coat across the wall to ensure the best final finish. Our Prep Coat creates an absorbent layer for the Limewash to adhere to on the surface, adding durability and avoiding over application of the Limewash. An inconsistent coat of Prep Coat will result in different levels of absorbency across the wall and can result in visible patches as the colour changes over these different levels of absorbency. If roller lines and straight-edged patches appear across the finished wall this indicates a patchy Prep Coat layer, this will be more obvious when painting with darker Limewash colours. To resolve patching caused by an inconsistent Prep Coat application, we recommend applying another coat of Bauwerk Prep Coat over the wall before re-application of Limewash.
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Q. How do I fix my walls that show white powdery patches ?
To resolve powdering or white patches from over-application, simply wait 24 hours and apply an additional thin coat of Limewash paint.
Tips + Tricks
- When applying the paint to a wall, have a look side-on from where you have applied. With the glare you will be able to see if there are areas with too much product.
- Make sure your brush is in good condition – not too dried out and clean of old paint etc.
- Be mindful to have the "right" amount of paint on your brush for the area or cloud you will be painting. Too little will also make it difficult to spread before it dries.
- When painting your clouds make sure to paint until it feathers out on the edges. This is a good indicator that the paint has been stretched. This with the first tip will help to keep the coats consistent.
Watch Tutorials
We would also suggest having a look at our YouTube tutorials, especially any that mention application over Prep-Coat.
Five Fab Limewashing Hacks
Limewashing with Colour 'Balance', a slightly darker neutral, for great texture and moody highlights in the room.
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