The appearance of brickwork can be spoilt by bad cleaning techniques or by the use of the wrong cleaning agent.

For this reason, it is important to ensure that the correct cleaning methods are utilised for the best results and to help reduce any associated problems with cleaning. Brick Manual 3 outlines the techniques that should be employed.

Acid cleaning using hydrochloric acid (HCl) should normally only be used to remove mortar stains. Generally, hydrochloric acid should not be used to treat any other stains or at any other time during the life of your bricks. If used incorrectly, it can cause unsightly staining that is more difficult to remove. The correct technique for cleaning mortar stains of brickwork with hydrochloric acid is given in Brick Manual 3.

Any vanadium stains should be treated prior to acid cleaning. Vanadium stains are a yellow-green harmless discolouration on the face of a clay product, which can occur especially in light coloured clay products. Acid cleaning prior to treating vanadium stains can result in the stain becoming more unsightly and more difficult to remove.
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Acid burn' is caused by the use of an incorrect acid cleaning procedure. The acid reacts with iron oxides naturally present in bricks or mortar to cause the stains.

Helpful acid cleaning tips:

• Always use adequate safety precautions!
• Reduce the need for acid cleaning by cleaning ‘as you go’ during laying.
• Ensure sufficient pre-wetting of the brickwork prior to applying hydrochloric acid.
• Apply an acid solution of the correct strength. Acid solutions that are too strong are a problem.
• Ensure that the brickwork is sufficiently rinsed after cleaning. Light coloured bricks should be rinsed with a neutralising solution.
  

High pressure water jets are often used during acid cleaning. The correct procedure must be followed so that the bricks and the mortar joints are not damaged by the process.

Helpful high pressure cleaning tips:

• Use the correct pressure (maximum 7000kPa or 1000psi)
• Keep the nozzle moving and use a wide nozzle angle (15°)
  Clean at a safe distance of 500mm. Never have the
• nozzle closer than 300mm to the wall.
• Dry press, slurry coated or glazed bricks should be cleaned by hand, not by high pressure water jets.

Refer to Brick Manual 3 for the full cleaning procedures.