CLEANING OF CLAY BRICKWORK
GENERAL PRECAUTIONS Staining can mar the overall appearance of bricks, but incorrect cleaning technique can cause permanent damage. Consequently any proposed method of cleaning should be tested in a small unobtrusive area and left for at least a week to judge the results before the whole job is tackled. The techniques given here are intended for do it yourself work in removing relatively small areas of staining. A specialist contractor should be engaged for cleaning large areas of brickwork.
Staining in many cases will disappear in time with normal weathering and traffic, however if after three months staining is still evident chemical intervention should in most cases solve the problem
It is preferable to use wooden scrapers and stiff fibre brushes to avoid damaging the bricks; but where chemicals are to be used, the bricks should be thoroughly wetted with clean water to prevent it absorbing the chemicals and rinsed thoroughly with clean water afterwards. Adjacent features, such as metal windows and the area at the foot of the wall, should be protected from splashing from the chemicals.
Many of the chemicals recommended are caustic, acidic or poisonous, so care should be taken and protective clothing and goggles should be worn. Volatile solvents should only be used indoors under conditions of good ventilation. It is essential to identify the type of stain or deposit before any cleaning operations are undertaken.
Note: Metal scrapers, brushes and the like should not be used on brickworks as it may cause damage.
PREVENTION IS BETTER THAN CURE
Cover bricks during building or renovating operations to prevent mortar and paint stains.
PREPARATION
Remember to thoroughly wet the bricks with clean water before applying any chemical and wash down with clean water afterwards. The main area of unsightly staining arises from the operation of laying the bricks in mortar and the related quantity of workmanship and management of the operation.
MORTAR AND MORTAR SMEAR
1. Where possible, remove large pieces of mortar with a wooden or nylon scraper (not metal).
2. Wet the bricks thoroughly with water, starting at the top and working down.
3. Wash the bricks down with a diluted solution of a proprietary mortar cleaner, used as per the manufacturer’s instruction. Scrub bricks using a stiff fibre brush (not metal).
4. Never allow the mortar cleaner to dry on the bricks. After scrubbing for a few minutes the bricks must be thoroughly washed with clean water to remove any acid residue.
5. Cleaning should be done in a relatively small area at a time working from top to bottom.
6. Should the mortar stain still be visible once the brickwork has dried out, steps 2 to 5 should be repeated.
EFFLORESCENCE – WHITE CRYSTALS OR WHITE FURRY DEPOSIT
Efflorescence is a usually harmless, although a unsightly phenomenon it does not require chemical cleaning to take place.
It usually disappears rapidly from new bricks by the action of wind and rain. Dry brushing or damp sponging down of the bricks at times where there is maximum efflorescence will also help.
LITCHENS AND MOSSES
These can be killed with a solution of copper sulphate (1kg to 10 litres of water) or, alternatively, a proprietary weed killer. Vegetable growth is generally indicative of damp brickwork and will usually reappear if this basic cause is not cured. (Green staining, which does not respond to this treatment, is probably due to Vanadium salts from within the bricks). Boiling water or steam is effective in cleaning mosses.
LIME AND LIME BLOOM
Follow treatment recommended for ‘Mortar and Mortar smear’. Lime staining in older brickworks, originating from the reinforced concrete structure, can be particularly difficult to remove. It is important to stop the flow of moisture through the structure to overcome the problem.
MANGANESE (DARK BROWN) Brush the stain with a solution of 1 part acetic acid and 1 part hydrogen peroxide in six parts of water.
PAINT
Apply commercial paint remover or a solution of trisodium phosphate (1 part to 5 parts water by mass). Allow the paint to soften, and remove with a suitable scraper (not metal). Wash the bricks with soapy water and finally rinse with clean water.
RUNNING WATER
Water running regularly down the surface of bricks produces pattern staining and this can frequently be removed by scrubbing after wetting with a high pressure mist spray of cold water (be careful of washing out the grouting). If this is not effective, the treatment recommended for ‘Mortar and Mortar Smear’ should be followed.
RUST OR IRON
Wash down with a solution of oxalic acid (1 part to 10 parts of water by mass). Brown staining which does not respond to this treatment, particularly at the junction of the brick and mortar, is probably due to ‘Manganese’.
SMOKE AND SOOT
Scrub with a household detergent.
TIMBER (BROWN OR GREY)
These stains are due to water spreading tannin or resin from the timber across the brick and mortar, and can normally be removed by scrubbing with a 1:40 solution of oxalic acid in hot water.
VANADIUM (GENERALLY GREEN / YELLOW IN COLOUR)
Wash down with a 20% solution of potassium hydroxide. Scrubbing is not necessary. Do not wash the bricks with clean water afterwards. Hydochloric acid should never be used on vanadium stains since it ‘fixes’ them and turns them brown.
Note: Light coloured clay bricks contain vanadium salts. Under certain conditions light coloured bricks are susceptible to vanadium staining, some more than others. To avoid vanadium staining it is important that the correct cleaning materials and methods are used.
VARIOUS OILS
Sponge with white spirits or carbon tetrachloride. Good ventilation is essential indoors when using these chemicals.
NB! This information has been supplied in good faith, Style & Craft Paving cannot in any way be held accountable for poor workmanship or errors that may occur through the use of this information
GENERAL PRECAUTIONS Staining can mar the overall appearance of bricks, but incorrect cleaning technique can cause permanent damage. Consequently any proposed method of cleaning should be tested in a small unobtrusive area and left for at least a week to judge the results before the whole job is tackled. The techniques given here are intended for do it yourself work in removing relatively small areas of staining. A specialist contractor should be engaged for cleaning large areas of brickwork.
Staining in many cases will disappear in time with normal weathering and traffic, however if after three months staining is still evident chemical intervention should in most cases solve the problem
It is preferable to use wooden scrapers and stiff fibre brushes to avoid damaging the bricks; but where chemicals are to be used, the bricks should be thoroughly wetted with clean water to prevent it absorbing the chemicals and rinsed thoroughly with clean water afterwards. Adjacent features, such as metal windows and the area at the foot of the wall, should be protected from splashing from the chemicals.
Many of the chemicals recommended are caustic, acidic or poisonous, so care should be taken and protective clothing and goggles should be worn. Volatile solvents should only be used indoors under conditions of good ventilation. It is essential to identify the type of stain or deposit before any cleaning operations are undertaken.
Note: Metal scrapers, brushes and the like should not be used on brickworks as it may cause damage.
PREVENTION IS BETTER THAN CURE
Cover bricks during building or renovating operations to prevent mortar and paint stains.
PREPARATION
Remember to thoroughly wet the bricks with clean water before applying any chemical and wash down with clean water afterwards. The main area of unsightly staining arises from the operation of laying the bricks in mortar and the related quantity of workmanship and management of the operation.
MORTAR AND MORTAR SMEAR
1. Where possible, remove large pieces of mortar with a wooden or nylon scraper (not metal).
2. Wet the bricks thoroughly with water, starting at the top and working down.
3. Wash the bricks down with a diluted solution of a proprietary mortar cleaner, used as per the manufacturer’s instruction. Scrub bricks using a stiff fibre brush (not metal).
4. Never allow the mortar cleaner to dry on the bricks. After scrubbing for a few minutes the bricks must be thoroughly washed with clean water to remove any acid residue.
5. Cleaning should be done in a relatively small area at a time working from top to bottom.
6. Should the mortar stain still be visible once the brickwork has dried out, steps 2 to 5 should be repeated.
EFFLORESCENCE – WHITE CRYSTALS OR WHITE FURRY DEPOSIT
Efflorescence is a usually harmless, although a unsightly phenomenon it does not require chemical cleaning to take place.
It usually disappears rapidly from new bricks by the action of wind and rain. Dry brushing or damp sponging down of the bricks at times where there is maximum efflorescence will also help.
LITCHENS AND MOSSES
These can be killed with a solution of copper sulphate (1kg to 10 litres of water) or, alternatively, a proprietary weed killer. Vegetable growth is generally indicative of damp brickwork and will usually reappear if this basic cause is not cured. (Green staining, which does not respond to this treatment, is probably due to Vanadium salts from within the bricks). Boiling water or steam is effective in cleaning mosses.
LIME AND LIME BLOOM
Follow treatment recommended for ‘Mortar and Mortar smear’. Lime staining in older brickworks, originating from the reinforced concrete structure, can be particularly difficult to remove. It is important to stop the flow of moisture through the structure to overcome the problem.
MANGANESE (DARK BROWN) Brush the stain with a solution of 1 part acetic acid and 1 part hydrogen peroxide in six parts of water.
PAINT
Apply commercial paint remover or a solution of trisodium phosphate (1 part to 5 parts water by mass). Allow the paint to soften, and remove with a suitable scraper (not metal). Wash the bricks with soapy water and finally rinse with clean water.
RUNNING WATER
Water running regularly down the surface of bricks produces pattern staining and this can frequently be removed by scrubbing after wetting with a high pressure mist spray of cold water (be careful of washing out the grouting). If this is not effective, the treatment recommended for ‘Mortar and Mortar Smear’ should be followed.
RUST OR IRON
Wash down with a solution of oxalic acid (1 part to 10 parts of water by mass). Brown staining which does not respond to this treatment, particularly at the junction of the brick and mortar, is probably due to ‘Manganese’.
SMOKE AND SOOT
Scrub with a household detergent.
TIMBER (BROWN OR GREY)
These stains are due to water spreading tannin or resin from the timber across the brick and mortar, and can normally be removed by scrubbing with a 1:40 solution of oxalic acid in hot water.
VANADIUM (GENERALLY GREEN / YELLOW IN COLOUR)
Wash down with a 20% solution of potassium hydroxide. Scrubbing is not necessary. Do not wash the bricks with clean water afterwards. Hydochloric acid should never be used on vanadium stains since it ‘fixes’ them and turns them brown.
Note: Light coloured clay bricks contain vanadium salts. Under certain conditions light coloured bricks are susceptible to vanadium staining, some more than others. To avoid vanadium staining it is important that the correct cleaning materials and methods are used.
VARIOUS OILS
Sponge with white spirits or carbon tetrachloride. Good ventilation is essential indoors when using these chemicals.
NB! This information has been supplied in good faith, Style & Craft Paving cannot in any way be held accountable for poor workmanship or errors that may occur through the use of this information
