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Masonry structures are built to last and offer an alluring natural charm to a home. However, our harsh Ottawa climate and hydrocarbon pollutants can cause masonry units to stain or weather loosing its visual appeal. To get your brick home or masonry structure looking like new again, it is important to first identify the stain, determine if it is a sign of a larger isssue (like water penetration) and then choose to appropriate method/procedure to remove the stain. Here are some of the most common stains on masonry home and how to address them:
Lime Run
Lime run looks like light white or gray crusty streaks running down the face of the wall. Lime run is comprised of calcium carbonate deposits that typically originate at a mortar joint that has had water flowing repeatedly through it. The flowing water carries calcium deposits that are absorbed from the mortar and brings them to the surface.
In order for lime run stains to be removed, you have to first address the water issue and prevent it from contacting the masonry again.
Lime run can be incredibly difficult to remove, however some success can be had with diluted acid cleaners (diluted muriatic acid and water). In many cases, the removal of stained bricks and installation of new ones is the only solution. For working with acids, we highly recommend hiring a licensed mason who is familiar with restoration work to try and remove lime run.
White Scum
White scum is created by Silicate deposits on the face of brickwork. White scum usually forms when brickwork is not properly cleaned with muriatic acid buffers after is has been constructed. Should the mason or helper not pre-wet the wall or rinse it well enough with clean water after scrubbing with acid, the remaining acid can cause a scummy "burned" look.
Special proprietary cleaners may be able to remove some of the white scum and are available at most brick supplliers.
Managanese Stain
Manganese staining is usually brown or gray in colour and is caused by a reaction of acids exposed to manganese oxide in the brick units. Mangese oxide is a colouring agent used to colour brown, gray, or black units.
Road Salt, water penetration and exposure to acid rain will cause these stains to occur. For removal, some success can be had with diluted muriatic acid solutions or a special proprietary compound available at most brick suppliers. Handling of acid cleaning should always be done by a professional restoration mason.
Vanadium Stain
Vanadian appears as a green or yellow stain and is caused by naturally occuring vanadiam salts that are present in some clay bricks. Walls exposed to moisture problems, or walls washed with unbiffured acids can cause vandium salts to crystallize on the surface.
To remove vanadium stains, one can mix 1/2 lb. of potassium hydroxide with 0.95 litres of water and apply it to the wall to soak in for 2-3 days followed by a thorough rinsing off with water. Other proprietary solutions are available at local brick suppliers.
Pollution/Environmental Stains
Pollution from combustion vehicles and factories can cause soot like stains to develop. On stonework, specialised lasers work well for the removal of tar-like stains. Some buffered acids, low pressure water, and/or poultices may also work to remove stains.
Organic compounds like algae and mold form over time in the presence of moisture. Low pressure water cleaning is highly effective.
Effloresence
Efflorescence is the most common form of staining seen in Ottawa. It appears as a white crust deposit on the surface of brickwork. It is caused by soluble salts and excess moisture that draws the salts in the brickwork to the face where the water evaporates leaving a salt deposit.
Since efflorescence is water soluble, misting or spraying along with a stiff brushing to the effected area can remove most of the efflorescnse. Effloresence is usually always a sign of moisture damage and usually leads to further damage like brick spall if the water issue is left unaddressed.
Conclusion
For all cleaning procedures, its is critical to speak directly with masonry manufacturers for the best advice on how to remove specific stains on specific materials. Masonry restoration specialists should always be consulted for the right procedures. In all cases, the gentlest, least harmful method should be used and a test sample spot should be done before cleaning an entire wall.
For more information on brick repairs and masonry restoration services, please contact Kavanagh Masonry by phone at 613-859-5090 or to request a quote, please visit the Request a Quote Page to get the process started. All restoration work is completed by a Red Seal Certified Brick and Stone Mason.
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