The appearance of a brick building can be permanently spoiled by bad cleaning techniques or by the use of the wrong cleaning agent. Because of this it is important to ensure that the correct cleaning methods are utilised for the best results. In order to help with this, Austral has provided some helpful hints to help reduce the associated problems with brick cleaning. Remember that the only function of hydrochloric acid is to dissolve portland cement.
Helpful Cleaning Hints
1. All mortar dags should be removed using either a metal or wooden scraper.
2. Protect all areas which may come in contact with the cleaning agent as recommended by the manufacturer.
3. Ensure that the area of brickwork to be cleaned is saturated with water.
4. Use the correct ratio of Hydrochloric acid and water
(a) Light coloured bricks - 1 part hydrochloric acid to 20 parts water
(b) Dark coloured bricks - 1 part hydrochloric acid to 10 parts water
* Under no circumstances should more than 1 part hydrochloric acid to 10 parts water be used. It is better to scrub more vigorously than to use more acid.
* Where vanadium staining appears on brickwork spot clean with a solution of 20 to 40 grams of oxalic acid per litre of water prior to cleaning with hydrochloric acid.
5. When cleaning try not to work in direct sunlight.
6. Always begin at the highest point and work down the wall.
7. Only clean small areas at a time, eg 1 square metre to ensure you have adequate time to wash off the cleaning solution to ensure no staining occurs.
8. Allow solution to remain on wall for 3 - 6 minutes before scrubbing. Be sure not to scrub the joints.
9. Rinse thoroughly, making sure that all cleaning solution has been removed.
* Light coloured bricks should be rinsed with a neutralising solution, such as bicarbonate soda or washing soda, instead of water.
Take Care With Cleaning
High pressure cleaning equipment can be used but the following simple precautions must be adhered to:
• Keep pressure low - around 1000-1200psi (6800-8500 KPa).
• Use a wide fan spray nozzle (15°)
• The nozzle should be generally 500mm from the wall or never closer than 300mm.
• Test a small unseen section prior to full scale cleaning to ensure best results.
• If the mortar joint or the bricks are being damaged then either the pressure is too high or the nozzle is too close to the wall.
Note: Austral does not recommend high pressure cleaning of dry pressed bricks.
• Always wear protective equipment such as gloves, safety glasses, etc.
• Store acid and acid solution in heavy duty plastic containers supplied by manufacturer.
• If cleaning solution comes in contact with body, irrigate area removing all traces of cleaning solution.