NATURAL STONE STONE g results. Here, the experts from BAL present a guide to fixing.

When installing natural stone with tile adhesives, special attention should be given to your choice of adhesive. Some carbonate-based stones, such as marble, travertine and limestone, may be susceptible to drawing in residual moisture from the tile adhesive, which has the potential to cause problems.

Because of this, we recommend fast-setting, cement- based white adhesives – such as BAL Rapid-Flex One – on walls and floors, or BAL Pourable One for floors with requirement for greater bed depths and when installing uncalibrated materials.

BAL Pourable One can offer bed thickness up to 25mm and can be grouted after three hours. The cement chemistry in this product uses up more of the water during hydration, thereby reducing the risk of water staining.

The use of BAL Pourable One can reduce the need to back butter – where surfaces are flat and even – providing sufficient coverage when the tiles or slabs are bedded down.


The risk of spoiling the effect of natural stone is greatest when the grouting stage is reached. It’s generally wise to choose a grout colour that is similar to the stone tile colour, particularly with porous stone.

On very porous stone, the result can be a rough ‘picture frame’ effect around stone edges, unless tiles are sealed

with a suitable sealer first. The risk can be reduced by using a rapid-setting grout such as BAL Micromax2.

When grouting natural stone, it’s advisable to carry out a trial on a small area to determine the potential for staining first. When in doubt, use a suitable protective sealer, such as BAL Protective Sealer, and repeat the trial to ensure a satisfactory result is achieved.

Finally, to ensure installation success, it’s important that movement joints are incorporated in the floor tiling. For perimeter movement joints, a suitable neutral curing silicone or similar is generally advised. That’s because acid curing sealants, such as acetoxy silicones, are bad news for some types of natural stone, especially marble and limestone. They chemically react with carbonates in the stone, causing de-bonding at the edges and, in some cases, breakdown of the stone.

In high-traffic areas, sealant movement joints should be avoided altogether because they will not protect the stone edge from damage. In these cases, proprietary pre- formed movement joints are recommended.

Overall, there is a lot for fixers to consider. But, by taking the appropriate steps at each stage, there is no reason why the beauty of a natural stone finish cannot be successfully installed and maintained for years to come.

For technical advice and training that can be trusted, contact BAL Technical Advisory Service on 03330 030160 or call the Innovation and Technology Centre on 01782 591120. — 25 —

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