Caring for your Clay Brickwork

Caring for Clay Brickwork

Hints and Tips on how to care for your clay bricks or pavers

  • Prevention is better than cure. Always cover the brickwork during building or renovating operations to prevent paint and mortar stains.
  • Staining can mar the appearance of brickwork but incorrect cleaning techniques can cause permanent damage. Always test any proposed¬†cleaning method on a small, unobtrusive area and examine after a week before tackling the job.
  • Know your limitations. The following techniques are intended to help you remove relatively small areas of staining. Hire a specialist contractor for large areas of brickwork.
  • Use wooden scrapers or stiff fibre brushes in order to avoid damaging the bricks.
  • Wet the brickwork with clean water before applying chemical solutions in order to prevent the bricks from absorbing the chemicals. Rinse thoroughly after the chemical application. Remember to protect metal window frames, doors, plants etc from chemical splashes.
  • Most of the chemicals quoted below are caustic, acidic or poisonous. Wear protective clothing and goggles when using them.
  • Volatile solvents should only be used indoors under conditions with good ventilation.
  • Identify the type of stain or deposit before undertaking any cleaning operation.
  • Unsightly staining often occurs when bricks are laid incorrectly. Bricklaying must be undertaken in a professional manner.

Stain Removal.

Mortar Stains

Remove larger pieces of mortar with a scraper. Thoroughly dampen the brickwork with clean water. Wash the stained area with a dilute solution of a proprietary acid cleaner (follow the manufacturer’s instruction carefully) and remove any residual acid by rinsing with cold water.

Mortar Smears

If the mortar smear shows signs of vanadium staining, follow the procedure for mortar stains, then treat the brickwork with a 15 to 20 % solution of Potassium Hydroxide.

Lime and lime bloom

Follow the treatment for mortar and mortar smear. NB: Lime staining is caused by free lime from mortar or concrete oxidizing on the surface of the brickwork. It thrives in damp conditions and can be difficult to remove from old brickwork for this reason. Eradicating moisture from the building will help to over come the problem.

Vanadium efflorescence

Vanadium Efflorescence are salts generally found in light coloured bricks that manifests itself as a green and sometimes brownish stains. Wash the brickwork with a 20% solution of Potassium Hydroxide. Do not rinse off afterwards. NB: Do not use Hydrochloric acid for vanadium stains because it will fix the stain and turn it brown.

Efflorescence

This white crystal or furry deposit usually disappears due to the action of wind or rain. If not, it can be removed with a firm bristle brush.

Lichens and mosses

Treat either with a solution of Copper Sulphate (1 kg to 10 litres of water) or a proprietary weed killer. Green staining which does not respond to this treatment is probably caused by vanadium salts in the bricks. NB: Vegetable growth usually indicates damp brickwork and will reappear if the damp is not treated.

Water stains

Water running continuously across brickwork will produce pattern staining. This can usually be removed by applying high pressure mist spray to the surface followed by a brisk scrubbing. If this proves ineffective, use the recommended treatment for mortar stains.

Various Oils

Sponge with white spirit, carbon tetrachloride or trichlorethylene. Ventilate the area well if indoors.

Paint

Apply commercial paint remover or a solution of trisodium phosphate (1 part to 5 parts of water by mass), Allow the paint to soften and remove with a scraper. Wash the wall with soapy water and rinse with clean water.

Rust and Iron

Wash the brickwork with a solution of oxalic acid (1 part to 10 parts of water by mass). NB: Brown staining which does not respond to this treatment, especially at the junction of brick and mortar, is probably due to manganese.

Timber (brownish-grey)

This stain is caused by water spreading tannin or resin from the timber across the bricks and mortar and can normally be removed by scrubbing with a 1:40 solution of oxalic acid in hot water.

Smoke and soot

Rub with a household detergent. Stubborn patches can be removed from the brick pores with Trichlorethylene. Ventilate well if indoors.

Tar

Remove excess tar from dry brickwork with a scraper. Then scrub the area with water and an emulsifying detergent. If necessary sponge with paraffin. NB: Do not use this method if the brickwork has surface damage.

Large projects / Multi-story buildings
  • Do not sand blast or high-pressure clean the stain unless under the supervision of an experienced contractor and with the prior agreement of the architect and NamClay.
  • Remove large mortar particles by hand
  • Cleaning should only commence 7 days after the brickwork has been completed and the mortar is firmly set.
  • Protect all surrounding metal, glass and wood surfaces before cleaning.
  • Work from the top of the building, downwards.
  • Saturate the walls with clean water before applying any chemicals

 

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