Up to Date with Ardex Part Four: Dealing with Lime Bloom

Up to Date with Ardex Part Four: Dealing with Lime Bloom

Q: What is Lime Bloom (Efflorescence)?

A: Lime Bloom can be seen as a lightening or light patches on the grout surface. This is normally a result of slow drying conditions which could be caused by a cold environment or an excess of mix water.

When the mortars remain wet for longer it provides ample opportunity for soluble lime to migrate to the surface.

Once the soluble lime is on the surface, it reacts with atmospheric carbon dioxide to form white calcium carbonate (lime bloom). Note that lime bloom is not the result of a product fault, but a naturally occurring chemical reaction.

Q: Is it permanent and how can I remove it?

A: Luckily the effect is not permanent and the surface discoloration can be removed using a proprietary cleaner containing phosphoric acid designed for such purposes.

The cleaner will effectively dissolve the thin film of lime bloom, exposing the intended colour of the grout mortar.

Sometimes, the cleaning process may be more difficult if latex components are present in the grout or adhesive.

These can also migrate to the surface and can form a protective barrier around the lime bloom making the acidic phosphoric acid mix less effective.

To counter this problem it’s best to use an acidic solution that combines cleaning agents to help break down the acrylic barrier.

As a word of caution, some acid sensitive tiling such as natural stones or polished surfaces may be adversely affected by an acid based cleaner.

In these cases, it’s far better to use abrasion to remove the bloom, using a stiff brush and mild detergent, but rinse well in order to stop the dissolved lime bloom from re-appearing.

Always seek advice and follow recommendations from the chemical cleaning manufacturing companies.

For any successful tiling project you need to start with high performance products. Ardex offers a comprehensive range of 35 tile grout colours which are all batch tested for accurate colour matching, and to ensure a consistent streak free finish.

The Ardex-Flex FS Flexible Tile Grout for Narrow Joints and Ardex-Flex FL Rapid Setting Flexible Tile Grout for Wide Joints are both dirt resistant and water repellent, providing a long lasting, stable colour finish.

For more information on Ardex click here.

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