How to remove efflorescence on tile grout

Tile grout efflorescence

Have you noticed a white deposit appearing on the surface of grout and/or tiles in your home? Don’t panic, it’s efflorescence – a salt deposit left behind as water evaporates from the surface, which isn’t harmful but can spoil the appearance of your tiles.

In this blog we’ll explain what efflorescence is, how to avoid it in the first place and how you can prevent it coming back.

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.

Calcium carbonate is not dangerous – it’s a completely natural substance found in limescale and even in common antacid medicines (though we don’t recommend licking your tiles clean to get rid of heartburn!).

You can remove efflorescence from your floor or wall tiles by following the 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: the use of excessive water and methods adopted in wiping off surplus grout from the tiles could 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 disappears after washing tiles with water and cleaning the joints with a stiff bristle brush. But it may reappear after drying. So it is obviously best to try and avoid the presence of efflorescence altogether during the installation by:

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    1. Removing moisture from the substrate

    In the mixing of setting materials, only clean water should be used and excess water should be avoided.

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    2. Eliminating soluble salts from the bedding and jointing materials

    In cement/sand bedding mortars or grouts, the use of sea or channel sand should be avoided, and only washed sand should be used. In general, use of proprietary adhesives and grouts eliminates many of the sources of these salts.

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    3. Avoiding accelerators

    The use of accelerators in the setting material should also be avoided, as should the use of lime in any cement/sand mortar.

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    4. Planning for high humidity

    In areas of high humidity, grouting should be avoided when temperatures fall.

How can efflorescence be removed?

Occasionally the deposit will just disappear with time, however, more often than not 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 washing off 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 have dried to the required colour. Otherwise, once sealed, there will be no means of removal of the salt deposit.

Any questions?

If you're unsure about anything you've read in this guide, please feel free to get in touch with our Technical team who are available to answer any questions you may have.

The team is available Monday to Friday from 8:30am until 5pm.

Simply call (01525) 722 100 option 2.

Click Compare to help you choose the right product for your project, if you need further assistance please email technical@netweber.co.uk

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