Maintaining bricks

How do I remove oil and bitumen stains?

Oil stains

Oil does not penetrate readily into clay pavers, but if oil is spilt on the pavers, the spillage should be removed promptly with an absorbent material, such as paper towels. The oil should not be wiped up; otherwise this will spread the contamination on the surface of the paver.

Steam cleaning can be used on clay pavers to remove such staining, but if this is unsuccessful an emulsifying de-greaser should be employed. Brush with plenty of water to safe disposal. An alternative cleaning method is to brush the area with a strong detergent and hot water. This will not affect the colour of the clay paving.

Bitumen stains

Bitumen does not penetrate readily into clay paving. The best method of removal is to leave the bitumen until it has cooled. A paint scraper or a similar mechanical device can then often remove it. If it is particularly resistant, the use of ice to make the bitumen even more brittle may be required, prior to scraping it from the paving.

Any residue should be removed with a scouring powder and finally the whole area rinsed with clean water. Certain proprietary cleaning agents are available to remove bitumen, but these should be tested on an inconspicuous area of paving first.

How do I remove cement stains on brick?

Remove large deposits with wooden implements to avoid damaging the paver surface. Following the pre-wetting of the area, treat the residue of mortar by careful application of a dilute hydrochloric acid solution or a proprietary cleaning solution. The application of the acid breaks down the cementitious components but is not damaging to clay pavers.

As with all cleaning procedures a rinsing operation should be carried out shortly after  application, and care taken to dispose of run off solutions safely.

If the above method is not successful with coloured mortars, specialist advice from the coloured mortar supplier should be sought.

On the rare occasions when a vanadium efflorescence is present, hydrochloric acid based cleaners must not come into contact with the efflorescence, otherwise a dark stain will result which will become fixed on the surface.

Are clay bricks petrol & diesel resistant?

A burnt clay facebrick type product is resistant to petrol and diesel. For many years Caltex specified only clay pavers for their garage forecourts for this reason (Tarmac was never used as petrol and diesel attack it) Although petrol can stain bricks, they are easy to clean.

Acid resistant clay tanks are common in industry and these willl also cope best with petrol and diesel. We would suggest a specialized mortar and possibly a lining is used. There are many specialist suppliers – just search the net!

The acid and chemical resistant clay bricks are featured products in various construction and refractory applications and are available in various shapes and types such as Arch Bricks, Tapper Bricks, Sleeves, Tongue & Groove Bricks.

Chemical resistant clay bricks are used in following application areas:

  • Chemical plants: Dyes, Intermediates, Acids and Alkalies
  • Fertilizer Plants
  • Thermal power plants for chimney construction
  • Petrochemicals and refineries
  • Pharmaceuticals etc
  • Galvanizing Plants

How can I remove paint on my brick wall?

Fresh wet paint should be soaked up with an absorbent material without wiping the paint, as this will spread the stain. It should then be treated with a suitable solvent, such as white spirit, and then the area washed with a de-greasing agent taking care in the disposal of the run-off material.

Brick is porous, so paint sinks into all the grooves on the surface. Chemical and gel masonry strippers are the solution for inside walls; and while the process of stripping the brick is not complicated, it involves multiple applications of stripper and lots of scrubbing, making it a time-consuming project. It is impossible to scrape like wood, and interior walls cannot easily be water- or sand-blasted.

Pressure washing should NEVER be used as it can quickly erode the surface of bricks. Some caustic chemical solutions can cause surface failures or can change the color of old bricks. Rapid deterioration is then likely to occur, resulting in the need for major repairs

With dried paint, the paint should be scraped off as far as possible and then a paint remover to BS3761 (4) should be applied.

  1. Put on safety goggles, a face mask and work gloves to avoid coming into contact with the stripper chemicals or fumes.
  2. Brush the masonry paint stripper generously over the brick wall with the brush, starting with one corner and working outward and downward. Reposition the ladder to work on the top of the wall first all the way across; then continue working on the next section until the entire brick has been covered in stripper.
  3. Wait the amount of time specified by the manufacturer. Then begin at the top of the wall again and scrub the masonry paint stripper off with a stiff-bristled brush. Paint will come off in chunks and flakes; continue to wear the protective gear. Scrub the entire wall with the brush, removing as much of the paint as possible.
  4. Wash the brick wall with rags and warm water to remove clinging paint and the stripping compound. Allow it to air-dry.
  5. Reapply another layer of masonry paint stripper to remove stubborn paint. Allow it to sit on the brick and scrub again. This step may have to be done several times to get most of the paint off the brick wall. Repeat the rinsing process to remove the stripper.
  6. Spray the stripped brick wall with white vinegar, and scrub off any remaining paint residue with a clean brush. Rinse with water.

 

How do I remove moss & algae from bricks & paving?

It is common to find growths such as algae, lichens, liverworts and moss growing on hard surfaces. Contrary to popular belief, they do not damage what they are growing on, but can cause patios, drives, paths and steps to become slippery.

Moss, lichens and algae should not grow on clay bricks unless the area is heavily shaded, is under trees, or is not laid to an adequate fall. If such growth does occur and is considered undesirable then the area should be treated with a proprietary moss killer used in accordance with the manufacturer’s instructions.Such products take some days to be effective and work best when applied during a spell of dry weather. Any thick growths should be scraped off first and the chemical treatment well brushed in.

Some treatments leave a residue to discourage the re-growth of the moss and algae, but this will only be of limited value if the paving remains damp and in shade.

Non-chemical control

  • Dislodge moss from between paving by running a sharp knife along the cracks. Alternatively, use a block paving brush with a long handle, narrow head and wire bristles for effective cleaning without stooping
  • A pressure washer will remove moss and algae effectively.  However, use this method with care in areas where drainage is unsatisfactory as the extra water could exacerbate damp problems. Always wear goggles when using a pressure washer.
  • Brush hard surfaces with a stiff broom on a regular basis to help prevent growths from taking hold. Raking loose surfaces such as gravel helps to keep these areas free of both moss and weeds
  • Prune overhanging plants to improve air flow – this will allow the drying effects of sun and wind to reach the site
  • Ensure surfaces slope slightly to prevent standing water
  • Improving drainage in the surrounding area will also help to deter growths. Dig out shallow channels along the edges of paths, patios and drives and fill with coarse gravel to absorb run off water
  • Fork over beds close to damp surfaces to maximise drainage and water absorption
  • Only pave areas essential for access. Choose permeable paving when constructing new hard surfaces and keep drains clear of leaves and debris
  • Surface finishes that are raised to give grip in wet weather are ideal for shady spots. Spreading coarse sand over garden steps is another simple anti-slip solution

How do I prevent salt damage at the coast?

Please refer to our Technical guides under `SALT ZONES` and salt erosion of clay bricks.

If you have a property situated on the beachfront there is usually some degree of deterioration taking place! All bricks are porous and will absorb salt, and many factors are at play so it is impossible to say how long it will be before deterioration of the façade begins. The softer lime mortar used in external brickwork prior to the 1960’s can be substantially affected by salt deterioration. This is more prevalent in the exposed location but  buildings located 2-3 kilometres from the sea can also be affected. The mortar becomes soft and powdery.

More recent Calcium Silicate face bricks can still suffer from surface delamination. This occurs as the salt crystals adhere to the brickwork and are absorbed into the bricks. During rain the crystals will expand and then push the outer surface of the brickwork away. Once the hardened surface of the brickwork is lost, then the rate of deterioration of brickwork will accelerate. It is not possible to prevent the surface delamination of bricks.

We have however noticed that the higher temperatured bricks like steel blues are holding out better than the reds/yellows and browns. Smoother textures are better than others at resisting the attack in severe zones.

In many cases, the problem is concentrated at ground level due to rising damp or minerals added to soil as fertilizer. The location does give easy access to undertake repairs.

The best solution in my opinion is to remove all the flakes from the damaged bricks, brush them down and then to plaster the ground floor brickwork and paint to a chosen colour, which would best suit your building.

A well plastered smooth finished wall with waterproofing additives would prevent the ingress of salt and would therefore not deteriorate in the same way. Only normal painting at intervals will be required. 

If the decision is to replace the brickwork with a new face brick finish, then it could be done but we would then suggest a low porosity brick with a smoother surface (not rustic textured which holds more salt). This would lengthen the life of the brickwork although it is impossible to say how long before the same type of damage occurs again. Individual bricks can be replaced as well, but this is an untidy solution, as the new bricks will look odd (another colour and size) and it will take an enormous amount of time.

The third concern after mortar and bricks, is the rusting and deterioration of the wall ties, which secure the external skin of brickwork to the main building. With complete rusting of the wall ties, this will allow the external brickwork to bow out as it is unrestrained and in extreme cases can cause complete collapse of the external skin of brickwork. In corrosive environments, stainless steel wall ties are recommended during construction.

Clive Archer
Managing Director

Crammix Bricks

As with all cleaning procedures a rinsing operation should be carried out shortly after  application, and care taken to dispose of run off solutions safely.

If the above method is not successful with coloured mortars, specialist advice from the coloured mortar supplier should be sought.

On the rare occasions when a vanadium efflorescence is present, hydrochloric acid based cleaners must not come into contact with the efflorescence, otherwise a dark stain will result which will become fixed on the surface.

Should I seal my paving?

Mark Hunter-Smith of Algoa Brick advises:

“Any form of sealant or dressing on a brick automatically turns a maintenance free product into one that has to be maintained as the sealer will weather and or peel off over time. The only time this has limited success is internal feature walls that are protected from the elements. Sealing traps moisture in the bricks and wall and cause softening and failure of the mortar. In most older buildings you will be able to see that the bricks to not fail, it is the mortar that crumbles or splits.

“Applying a sealer to an external paving situation is probably the hardest to do as it is totally exposed to weather as well as car tyre abrasion etc. It has no roof overhang to protect or vertical walls for rain to run down i.e horizontal surface taking full pounding. I do not think a sealer will last very long in this application especially in the high wear areas which can create a patchy type finish. Also a sealer makes the paver waterproof so rain water pooling occurs and also surface can become rather slippery.

“I would suggest rather a good clean with a high pressure setting of a garden hose using industrial type soap like Teepol. If dirt very stubborn a weak acid cleaner can be used.”

What is the white, powdery substance on my bricks?

Efflorescence is a powdery deposit of salts which forms on the surface of bricks and paving. It is usually white but efflorescence can be yellow, green or brown.

Efflorescence does not in any way influence the structural strength of clay bricks or pavers. Roman buildings that have been standing for 2 000 years can show efflorescence

A temporary efflorescence is particularly common on new brickwork and paving as soluble salts are dissolved and transported to the surface of the brickwork and paving by water. The efflorescence on new well fired brickwork and paving may be unsightly, but it will not cause damage unless the brickwork and paving are under-fired or soft-fired, in which case serious efflorescence can cause flaking of the surface of the brick or paver.

Efflorescence can occur from a variety of sources. Besides the brickwork, soluble salts can originate from the sand, mortar and the water used. Ground waters that are naturally salt-bearing can be drawn into the base of the brickwork and paving.

Remedies

The best removal method is simply to brush off the deposit with a stiff dry bristle brush after the wall has dried out. Collect the removed salts with a dust pan or a vacuum cleaner to prevent the salts re-entering the brickwork. Wetting the wall by methods such as hosing usually dissolves efflorescence back into the brickwork, allowing it to reappear again when the wall dries out.

Acid or alkaline treatments are not recommended as they do more harm than good because they add to the total salt content.

High pressure washers can remove the surface of the brick, resulting in serious deterioration in the long term.

Dries V of Cermalab