What is the white substance on bricks and how to remove it?

Do you have a coating of white powdery stuff on your exterior brick walls?  The name for this white powder is efflorescence.

Masonry contains natural salts (sodium and calcium chloride).  These salts are trapped within masonry in stable form until they are dissolved in water.  In the winter, heat in the building drives this moisture in front of it. When the water/salt solution reaches the exterior wall surface the cold, dry air evaporates the water, leaving the salt as a white crystallines on the surface.  Although it can occur year-round, it is most likely to form during the low temperatures of winter.  Protecting your brickwork from the Winter weather is vital.

Although unsightly and undesirable, efflorescence is usually not harmful to brick masonry.  However, it is an indicator of the presence of excess water in the masonry, which can lead to more serious issues.


The removal of efflorescence from masonry is a relatively easy.  Most efflorescing salts are water-soluble and will disappear without any intervention through normal weathering.  It is usually not advisable to wash efflorescence off of the brickwork except in warm, dry weather.  Many efflorescing salts can be removed simply by dry brushing.  Brush off the deposit with a stiff dry bristle brush when the wall has dried out. Collect the removed salts with a dust pan to prevent the salts re-entering the brickwork.  Wetting the wall by methods like hosing usually dissolves efflorescence back into the bricks, allowing it to reappear again when dry.  This is not advised. Resist the temptation to break out the pressure washer.  High pressure washers can remove the surface of the brick, resulting in serious deterioration in the long term.  Acid or alkaline treatments are not recommended as they do more harm than good, as they add to the salt content, making efflorescence worse.

Efflorescence requires both the presence of soluble salts and moisture.  Eliminating either will help prevent or minimise possible efflorescence. Design and construction that promote resistance to water penetration are the most effective methods of preventing efflorescence.  Things like having good drainage, to prevent standing water.  Having paving sloped away from the walls to encourage run off.  Having well maintained guttering.  Good maintenance, removing and moss or algae build up.

With garden or driveway walls this includes using overhanging coping stones to direct the flow of water away from the wall. Copings can come with a drip channel placed under both sides to ensure rain water will not run down the face of your wall. Coping must overhang the wall by a minimum of 30mm each side in order for the drip channel to function properly.

Coping Stones and Pier Caps are essential, practical and ensure your garden wall has an attractive finish while carrying out the important job of preventing rainwater dripping down the surface of your wall.

Read more on building a garden wall with out Top tips for building a garden wall.

Some people may choose to paint their garden or driveway walls.  This can dramatically improve the aesthetic of a boring garden wall in an instant.  But it is important to consider this carefully before carrying out such work.  You need to remember bricks need to breathe.  They need to be able to expel moisture and when you coat them with paint you have effectively closed the pores of the bricks preventing them from breathing.  Ensure you choose the correct paint or wall coating system for the job.  It has to allow water to exit the brick, avoiding trapping it inside, causing water damage and the brick to crumble when it freezes in winter.  It does this by microporous technology, allowing damp and moisture out but not in.


We can often manufacture Pier Caps and Coping Stones to match your exact specification using our specialist mould making techniques. Contact us today to discuss your project requirements.

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