Lime bloom and how to fix it!

An example of lime bloom before treatment

Have you ever experienced lime bloom in your coloured render? This usually only occurs in cement-based products such as Monocouche.

Lime bloom is caused by the acids from the cement coming up to the surface of the colour making it patchy and white, sometimes showing the pattern of the block or brick underneath and usually occurs during the curing process after the product has been scratched or finished.  

We have a simple guide below to demonstrate how to recover your render:

  1. Wash the area down so that it is all damped down
  2. Mix brick acid – 80% water to 20% acid – and brush onto the render using a white clear brush (do a test area to start with to make sure that it doesn’t stain)
  3. If the test area is good, damp down the larger area again and brush on your acid water mixture
  4. After the acid mixture is brushed on, immediately wash off the area with clear water. Do not leave the acid mixture to dry ( if using a jet wash, hold the nozzle about half a metre minimum away from the render to avoid any damage)
  5. Once the area is cleaned off, make sure any other areas splashed are cleaned off
  6. Allow to dry to see the results, this should reduce the amount of lime bloom on the surface of the render

You may need to repeat this process as many as three times to remove the lime bloom from your render.  Do not increase the strength of the acid water mix thinking this will reduce the lime bloom as a stronger acid water mix may discolour the render. 

Please take care and wear the correct PPE when applying the acid.  

Thank you for reading our blog if you have any issues you’re unsure of regarding lime bloom, please contact your render manufacturer for further details. 

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