Product watch: inside the ceramic craft behind the Japanese WASHLET from TOTO

Best known for bringing advanced Japanese shower toilet technology into the bathroom, TOTO has established itself as a leading manufacturer in the category. Yet, behind its signature WASHLET lies something altogether more fundamental: ceramic. Hotel Designs takes a closer look at the material, craftsmanship and precision behind its distinctive white form.

For all its associations with advanced bathroom technology, the WASHLET begins with clay – a simple, natural material shaped, refined and transformed by fire into something enduring. The ceramic bowl beneath is made from the same family of materials as everyday tableware, but engineered for a very different purpose. Through precision moulding, the organic, pebble-like silhouette takes shape, creating the distinctive white form beneath the WASHLET.

Achieving that consistent finish begins with the raw materials themselves. TOTO sources locally wherever possible, while also procuring specific materials internationally when required to meet its standards. The same level of care extends to transport: materials are typically shipped in food-grade containers to prevent contamination.

During the container shortages that followed the Covid-19 pandemic, these food-grade containers were not always available. In those cases, TOTO used standard containers lined with protective sheeting to create a clean internal environment and prevent impurities from coming into contact with the materials. This attention to detail helps safeguard the quality at every stage. The production process begins with more than 20 natural raw materials, including clay, feldspar and pottery stone. Combined with water and finely milled, these ingredients become a liquid clay, known as slurry, which is poured into moulds to create the bowl.

What emerges already resembles the finished ceramic, but at this stage it remains soft, unfinished and deliberately oversized. During drying and firing, TOTO’s sanitary ceramics shrink by approximately 13%, meaning the final proportions must be anticipated long before the piece reaches the kiln. This is where a highly controlled manufacturing process meets the hand of the craftsperson. Depending on the design, sections of ceramic are joined, surfaces smoothed and curves carefully refined in preparation for glazing. Automation plays an important role in production, but the material still demands human judgement, precision and skill.

The glazing process gives the ceramic its characteristic white finish, while also incorporating one of the brand’s best-known technologies into the material itself. As Tomoyasu Ichiki, Director of TOTO’s Research Institute, explained: “Just like the base material for sanitary ware, glaze was traditionally made from natural raw materials”.

CEFIONTECT is TOTO’s proprietary ultra-smooth ceramic glaze, developed to make it more difficult for dirt and waste to adhere to the bowl. Its development involved extensive experimentation with different glaze compositions, bringing together traditional ceramic knowledge and modern material science. Satoshi Horiuchi, Executive Vice President of TOTO Sanitechno Co., Ltd., looked back at the experimentation behind its development: “I created dozens of ‘recipes’ for glaze ingredients and tested them for anti-stain properties.” The breakthrough ultimately came from applying two different layers of glaze, rather than relying on the conventional single-layer finish.

Firing these layers together presented its own manufacturing challenge. “We only fire it once,” said Ichiki, describing what makes the process distinctive. At temperatures reaching approximately 1,200°C, the two glazes must retain their individual properties rather than simply melting together, requiring precise control of their composition and firing conditions.

The result is a highly refined, glass-rich surface integrated into the ceramic itself. At a microscopic level, its irregularities are considerably smaller than those found on conventional ceramic. CEFIONTECT is also hydrophilic, encouraging water to spread readily across the surface and helping particles to wash away. For hospitality interiors, that performance has a practical consequence. A finish chosen for its clean, seamless appearance must also withstand repeated use and regular housekeeping while retaining its quality over time. After firing, the ceramic is inspected for dimensions, colour and finish, along with checks for flaws that might not be visible to the eye. Only then is it ready to become part of the completed shower toilet.

What appears as a seamless white form is therefore the result of careful material selection, skilled handling and tightly controlled production. Its apparent simplicity belies the complexity of its creation, with each stage, from the composition of the clay to the formulation of the glaze, contributing to the quality and performance of the finished ceramic. In TOTO’s WASHLET shower toilet, ceramic is more than a backdrop to the technology above it. It plays an equally important role in the product’s durability and performance, demonstrating how natural materials, traditional craftsmanship and advanced manufacturing can come together in a single, carefully considered form.

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Main image credit: TOTO