The free diy home improvement guide with answers to your questions on a wide range of do it yourself projects.


Efflorescence, What is it & What to do

Efflorescence sounds like the name of a rock band or a type of flower arrangement, but actually it can be an unsightly and annoying problem which occurs on masonry and plasterwork. It is a name for white deposits which come out of brickwork and plaster destroying the look of your hard work. No matter how many times you attempt to wash it off it never seems to go. So what can be done to both prevent these deposits and how do you get rid of it once it is there.

Masonry Efflorescence

  • On brickwork, efflorescence will show itself as a haze of white across the surface – an almost chalky whiteness. Generally it is caused by water within the bricks reacting with the salt in the construction materials. The salt dissolves and comes to the surface due to evaporation.
  • If the source of the damp within the bricks has been found then the bricks can be cleaned down and the problem will not recur. However bricks which are near outside taps or drains may continue to have the problem. It is important to check for other sources of damp such as ground water and damp.
  • Once the source of the water has been found the walls can be coated with a salt neutraliser which can be applied to the bare bricks to prevent water coming out of them in the future.
  • Some efflorescence is caused by free lime which is the result of a manufacturing fault which occurs during the curing of the brick or mortar.

Plaster Efflorescence

  • Internal walls can also be subject to efflorescence which appears as white fluffy salts on the surface of the wall. They will be crunchy to touch and may occur behind wallpaper and paint.
  • Once again this is caused by water within the walls making its way to the surface. Water could be coming from an internal leak within the wall or from the outside walls coming through the brickwork and causing damp.
  • Once the source of the water is found the walls can be painted with a salt neutraliser providing the bare walls are treated. If the walls have become damaged beyond repair then the plaster will need to be removed. It may be wise to apply a damp-proof membrane behind the affected wall before applying new plaster.

In all cases of efflorescence, do not wash it off with water, this will simply exacerbate the problem; forcing water back into the walls. The best thing to do is to use as stiff brush to remove the white bloom or to use an acid wash which can be purchased from a DIY store.