EFFLORESCENCE ON PLASTER SURFACE – WHAT, WHY & HOW?

What is Efflorescence on a Plaster Surface?

Efflorescence is a type of defect found on the surface of plaster. Efflorescence is a white crystalline substance that appears on the surface of walls due to the presence of soluble salts, such as sulfates of sodium, calcium and magnesium.


Why does swelling occur on plaster surfaces?

The presence of salts in lime, cement, sand, bricks and sometimes even water used in construction work causes flaking on the plaster surface. after the plaster work is completed and when it is completely dry; Soluble salts dissolved by moisture are drawn to the surface through pores. These soluble salts absorb moisture from the atmosphere and on drying get deposited in patches as a white crystalline substance. The ugly moist patch of pupil distorts the surface. This defect gradually disintegrates the structure. It is usually temporary in nature as it disappears during the wet season and reappears during the dry season.

bloom on plaster
bloom on plaster

How to fix or what are the remedies?

  • The flowing salt cannot be removed by rinsing with water as it can carry some of the salt back into the pores.
  • Dry brushing of visible growths on the surface is one of the treatments.
  • Treating an old wall with a silicone solution will often stop flowering because the liquid blocks the path for the movement of moisture.
  • When weathering occurs due to the rise of salt solution through capillary action from the sub-soil; The only solution is to provide bitumen or metal seals in the walls above ground level to create an effective barrier to capillary action.
  • In the case of brickwork, the salt can be removed with a solution of zinc sulfate and water. The surface is brushed when dry.

How to stop inflorescences in a new building?

  • Cement gauged lime mortar or medium hydraulic lime mortar or cement mortar with small proportions of alum and soft soap should be used throughout the work. If possible, use a water proof mortar.
  • Wherever necessary, damp proof courses should be used.
  • Only burnt bricks and clean water (free of salt) should be used.
  • Masonry or plastered works should be well protected at night and during rains to exclude excess water.

Er. Mukesh Kumar

Photo of author
Er. Mukesh Kumar is Editor in Chief and Co-Funder at ProCivilEngineer.com Civil Engineering Website. Mukesh Kumar is a Bachelor in Civil Engineering From MIT. He has work experience in Highway Construction, Bridge Construction, Railway Steel Girder work, Under box culvert construction, Retaining wall construction. He was a lecturer in a Engineering college for more than 6 years.