How to Clean Masonry

By their very nature, masonry materials are hard, durable, and long-lived, making them an excellent building material.  Over time or when first installed, they can require aggressive cleaning methods to remove accumulated dirt or excess mortar.  It is important to proceed according to manufacturers’ instructions and use the right type of cleaning technique and product.

Prevention is the best way to reduce or eliminate the need for cleaning.  Proper wall design and construction practices will reduce the need for cleaning.  During the construction process, store materials off the ground and under cover; protect work-in-progress with tarpaulins; ‘work clean’ by reducing mortar drops and smears. 

Despite our best efforts, cleaning may become necessary.  Different types of masonry materials require different cleaning products and methods.  For the purpose of this guide we will separate masonry into two groups:

  1. Manufactured Stone Veneer
  2. Clay Brick/Architectural Heavy Weight Concrete Masonry and Natural Stone

First, a word on efflorescence

Efflorescence is a white coating or powder that can appear on the face of masonry.  This often occurs on newly built structures when naturally occurring salts are brought to the surface of the masonry during the normal post-construction drying process.  This phenomenon is called ‘new building bloom’.  If caught soon after it occurs, the efflorescence can often be removed with by dry-brushing.  Efflorescence can also occur in established masonry structures if moisture finds its way behind the masonry, causing this drying process to continue.  By stopping moisture penetration, you will stop the efflorescence occurrence.

Brick wall with white efflorescence

Cleaning Manufactured Stone Veneer

Manufactured Stone Veneer is a product that has the appearance of natural stone and is manufactured with concrete. 

Chemicals are not to be used for cleaning manufactured stone, neither are stiff brushes or power washers

Cleaning tools for manufactured stone are to be non-abrasive, soft nylon brushes for example.

‘Working clean’ will typically eliminate the need for cleaning.  Manufactured Stone Veneer is applied to the vertical surface of walls using mortar, like installing tile.  It is a good idea to begin installing the stone at the top of the wall and work down to the bottom.  This practice will eliminate mortar droppings from fouling the stone below if the installation is started on the bottom of the wall.  If mortar is dropped on the face of the stone, let it cure to a slightly firm consistency and pick the dropping off with a clean stick.  Never wipe a mortar drop with a wet cloth or sponge, it will smear and become permanent.

Loose efflorescence can be brushed off manufactured stone veneer with a soft-bristle nylon brush.  For adhered efflorescence and other staining, try a mixture of 1-part white household vinegar mixed with 5 parts of clean water to clean the stone.  Wet-down the stone with a garden hose at low pressure and apply the detergent solution, brush lightly and rinse.

There is a product by EcoChem called EF-Fortless that can also be used in more severe cases.  Ef-fortless is a soap solution that counteracts efflorescence.  The product is mildly acidic and safe for virtually all surfaces including clay, concrete, and natural stone.

Dirt and soil can be removed using a mixture of granulated laundry detergent and water.  Wet-down the stone using a garden hose at low pressure and apply the detergent solution, lightly brush and rinse.

If these methods fail to remove stains from your manufactured stone veneer, you can use coloured stain to touch up the stone.  I-XL Building Products offers colour touch-up kits for many of our stone products.  These kits include colour pigments and other materials used in the manufacture of the stone, along with the materials needed to apply them.

A sealer like CraftShield can provide added protection and will usually make the stone easier to clean if the surface becomes dirty.  CraftShield is a silane and siloxane-based penetrating, breathable masonry sealer which will not change the look of your stone.

Clay Brick, Architectural Heavy Weight Concrete Masonry and Natural Stone

These traditional masonry materials are typically very hard, meaning that aggressive methods may be necessary for cleaning.  Recent innovations in masonry cleaning materials have brought much more environmentally sensitive masonry cleaning products to the market than have been available in the past.  Products such as those produced by EaCo Chem, like NMD80, do an excellent job of cleaning both clay brick and heavy-weight concrete masonry materials.

A final word on safety

Materials used to clean masonry are typically commercial grade chemical products.  Contact with the cleaners and their fumes can be harmful.  Strict adherence to manufacturer instructions is mandatory.  Cleaning should be performed only by professional personnel trained to handle the safety risks associated with cleaning these products. 

Each masonry material manufacturer and masonry cleaner manufacturer have their own recommendations for products and methods to be used to clean their products. Referencing the manufacturer’s website for products and recommended cleaning methods is always the first step in the cleaning process.

Some general rules to follow are to test a small area to ensure the results are as desired.  Take care with high-pressure sprayers.  Even the hardest and most durable masonry surface can be damaged if the pressure used is too high.  Professionals should be consulted for challenging cleaning jobs such as removing paint and graffiti; cleaning historic masonry structures; and the use of abrasives such as sandblasting.  A good rule to follow is use the gentlest method for cleaning that is effective.

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