Dealing with Efflorescence.

You may have seen a white powdery substance on brick and tiles. This is a natural phenomenon called efflorescence. Under certain circumstances, a white powder can form on unglazed terracotta type floor tiles. This is due to soluble salts rising to the surface from the concrete slab. When they dry out on the surface, the remaining salts appear white and powdery.

Efflorescence often occurs in the cement joints of new brickwork or grouting between tiles, especially shortly after they have been laid. Numerous studies have been made around the world to try to determine why it can appear in one location and not another under seemingly identical conditions. The only things that we do know are that it happens when Portland Cement is present and there is no real solution for it. Efflorescence does clear up over time unless there is an ongoing issue with rising damp from the substrate. It is defined as the 'migration of soluble salts.'

This is not due to substandard tiles, adhesives, or grout; and generally there is nothing to worry about.

The only real solution is to brush the grout with a stiff bristled brush and vacuum away. Commercial efflorescence removers are also available, these are generally acid based.

Repeat this from time to time and generally, it should eventually stop recurring.

Some people advocate brushing the salts away and then applying a penetrating tile sealer. While these are great products, and are worth using because they will keep your grout and tile clean and seal out dirt, these products generally won't stop efflorescence.

In most cases, penetrating sealer applied with a lambswool applicator will help as it works by allowing vapour to transfer through to the surface, but not moisture. It allows the tile to 'breathe' and can reduce the problem, although it is not guaranteed to always work, especially in outdoor areas.

You can also wash with a 50/50 mix of water and phosphoric acid. Leave the solution on the tiles for two minutes, then thoroughly wash off with clean water.

Always take care with stone (marble, granite, and sandstone) and acid sensitive products. First test in an inconspicuous area.