Grout was once viewed as a very prosaic product, simply used to fill the spaces between tiles – grey for floors, white for walls. But today’s grouts have a more pronounced role in successful tile installations. Joe Simpson reports.
While the main purposes of tiling grout – to seal the joints and protect them from dirt or stains, and to withstand any expansion and contraction of the tile – have not changed, coloured grout can radically change the look of any installation.
Traditionally white or grey, grout it is now produced in a large range of colours which can contrast with, or complement, the colour of the tiles, or even match the tile so closely that the grout joints are difficult to discern.
Bright yellow, red, and sparkly grouts have fallen out of favour and many have been discontinued as grout shades follow interior colour trends that favour more subtle tones.
Kerakoll has taken grout design one step further by commissioning designer and architect, Piero Lissoni to curate the colours for its new grout collection, Fugabella Color. The result is a range of 50 colours, from delicate neutrals and gentle pastels through to rich, intense shades that can either be used to create the illusion of a continuous surface or as an integral part of the design, notably in mosaic installations.
Of course, coloured grouts must be fit for purpose, with colours that do not fade, or stain. Without the correct formulation, UV light can bleach colours. In the past, some cementitious grouts have been prone to Portlandite, the unsightly salt and lime efflorescence caused by the inclusion of Portland cement. Recent product developments have resulted in products that do not have these problems.
For instance, Kerakoll’s Fugabella Color is a resin-cement hybrid formulated with a new mix of pure, natural binders that have been hybridised with resin binders and other additives. The particles used in the grout allow it to be produced in a wide range of rich intense colours. These particles have a defined shape and an optimised size distribution to deliver an even colour disbursement that remains stable over time. It is an advanced cementitious grout with enhanced water-resistance and antibacterial properties
As a resin-cement grout, Fugabella Color does not contain Portland cement so it is not affected by Portlandite. The resin hybrid formulation remains workable without changing consistency in the bucket, so there is no need to add water. This is something that can lead to colour inconsistency in traditional cementitious grouts.
Traditional grouts can be divided into two main classes. The first is cementitious grout: a powdered mix of cement binder and aggregate to which water is added. Advanced cementitious grout formulations feature additional components, such as polymers or biocides, to provide enhanced characteristics such as mould and bacteria resistance, or faster setting times. The second main class is reactive resin grouts, typically an epoxy resin mixed with a filler.
The market has been complicated by the emergence of products like Fugabella Color. The formulation of this resin-cement hybrid means that its performance values regarding abrasion resistance, colour uniformity, colour durability, water-repellence, stain resistance, and ease of maintenance are similar to those achieved by reactive resin grouts, but without the additional cost and difficulty of application.
Epoxy grouts tend to be more expensive than conventional cement-based grouts. They can also be more difficult to use and can cause allergic reactions in the people applying them. However, they set harder and do not break down as easily as cementitious formulations. This gives them advantages in specific environments such as areas where hygiene is important.
Many specialist tiling contractors remain firm advocates of epoxy (reactive resin) grouts. One reason is the impermeable characteristics of epoxy that makes it ideal for applications where hygiene is of the utmost importance, such as hospitals and food production facilities. For example, Mapei Kerapoxy is resistant to animal fats, oils, and grease, so it is an ideal grouting choice for meat processing plants and commercial kitchens. Mapei epoxy grouts also emit extremely low levels of VOC, and provide impressive mechanical and compressive strength characteristics.
At the other end of the scale, highly decorative products like Mapei Kerapoxy Design can add to a surface aesthetic, and dry to a translucent finish that is effective when used with glass tiles or mosaics. These impervious grouts are available in a spectrum of designer shades and can be enhanced by the addition of 23 colour options in Mapeglitter, making the grout joint a design statement.
Epoxy grouts can also be used in domestic applications as their durability, aesthetically pleasing appearance, and easy cleanability are all valued attributes. Over a long period of service, cement-based grout can discolour, stain, and soften with harsh cleaning products, but epoxy grouts offer years of efficient service without these common problems.
One reason why epoxy grouts are not used by more installers is their reputation for being hard to use, and for setting extremely quickly. This is changing because the latest generation of epoxy grouts are easier to install, with certain products. Mapei’s Kerapoxy CQ has been specifically designed with ease of application in mind. This is achieved through the use of specially graded coloured quartz.
In traditional epoxy grouts, the colour is derived from the resin, often leaving a coloured smudge-like residue over the surface of the tile that can be difficult to remove without a suitable cleaner. With Mapei’s Kerapoxy CQ, the colour comes from the quartz which simplifies the cleaning off process. And, with an average pot life of approximately 45 to 60 minutes, the rapid setting issue has been largely overcome.
The finishing process with epoxy grouts has also been improved. Most manufacturers will recommend a suitable cleaning product to help remove the slight haze left on the surface of the tile after installation. For instance, Mapei Kerapoxy Cleaner is designed to be used with the Mapei Kerapoxy grout range, and available in an easy-to-use spray bottle applicator. There are now epoxy grout formulations that can be cleaned off without fuss just using water, white felt, and a cellulose sponge.
Some products challenge traditional definitions of grout. For instance, Litokol Starlike (which has been available for more than a decade now) resolves three different requirements: bonding, sealing, and smoothing. In effect, it is an epoxy grout that can also be used as an adhesive and levelling product for wall applications.
Starlike, a UV-resistant epoxy sealant for both indoor and outdoor use, is billed as a new way of designing surfaces where colour variation is an essential element of the design. As well as a vast colour choice, divided into three families, Starlite has built-in antibacterial qualities and is thus suitable for healthcare facilities, laboratories, public swimming pools, commercial kitchens, and other hygiene-sensitive locations.
But it is the aesthetic appeal that really define the range. Starlike Crystal is designed for grouting glass and artistic mosaics. It is formulated to absorb the colour of transparent glass tiles and to change depending on the host tile’s colour. The neutral-coloured translucent joints are ideal for artistic mosaics because they highlight the colours and do not interfere with the overall look.
Joe Simpson is the international correspondent for Tile Today magazine.