Preventing and removing efflorescence from tile grout

What is efflorescence?

Efflorescence is a white deposit (usually calcium carbonate) that develops on the surface of grout and/or tiles as they dry out. It happens when soluble, naturally occurring mineral salts contained in Portland cement, or materials used in conjunction with it, rise to the surface.

It’s a completely natural substance found in limescale and even in common antacid medicines and therefore isn’t dangerous.

You can remove efflorescence from your floor or wall tiles by following our handy tips below.

What causes efflorescence on tiles?

The mineral salts that cause efflorescence can come from the background render or screed, as well as from the tile adhesive or grout that the tiles are fixed to.

Efflorescence can be caused by:

• Ongoing damp or humidity: this may occur after completion of an installation or where there is a prolonged delay in drying out.

• Inadequate damp-proofing: persistent efflorescence can come from inadequate damp-proofing in the wall or floor structure.
• Naturally occurring salts in products: soluble salts present in the jointing material, adhesive-bed, or substrate on which the tiles were fixed.
• Methods used to finish grouted joints between tiles: use of excessive water and the methods adopted in wiping off surplus grout from the tiles can result in fine particles being brought to the surface along with the soluble salts.

Evaporation or hydrostatic pressure (pressure exerted by a fluid due to its weight) must occur for the salts to migrate to the surface. With time, efflorescence will lessen, unless your tiles are exposed to a continuing external source of salts and water.

How can efflorescence be avoided?

Efflorescence often appears to diminish after washing tiles with water and cleaning the joints with a stiff bristle brush, but it may reappear after drying. Therefore, it’s best to try and avoid the presence of efflorescence altogether during the installation by:

How can efflorescence be removed?

The deposit may just disappear with time, however, often it is necessary for chemicals to be used. Here are some tips for using chemicals to remove efflorescence:

Use safe, acid-based, proprietary products in accordance with the manufacturer’s instructions. Leave it in contact with the surface for a few minutes before thoroughly rinsing with clean water.

Please note: HG Limex or Lithofin Cement Away are suitable but should not be used on marble or limestone floors, as they will attack the tile surface.

When tackling large areas, treat a small test area first. You want to be sure you’re using the correct techniques before you try treating the whole floor or wall.

Allow any new tile installation to dry out thoroughly before any sort of treatment with acid cleaners, as efflorescence could reoccur if more soluble salts are brought to the surface.

In general, sealing of floor tiles is not recommended. However, if used – for example, on terracotta tiles – then the installation should be allowed to dry out completely and the grout has dried to the required colour. Otherwise, once sealed, there will be no means of removal of the salt deposit.