On a Molecular Level: How Natural Stone Is Really Protected
Natural stone is one of the most timeless materials we work with every day at Hochwert. Marble, limestone, travertine — every slab tells its own story, shaped over millions of years, unique in grain and character. These very qualities are what make natural stone one of the most sought-after materials in refined interiors: robust, elegant, and possessing a presence that only deepens with time.
Yet the same properties that make natural stone so valuable also make it vulnerable. Stone types like marble or limestone consist largely of calcium carbonate — and react sensitively to acids. A splash of wine, a few drops of lemon juice, a spritz of perfume: even the smallest amounts can leave permanent stains, often removable only through extensive grinding of the surface. Cementitious surfaces are not exempt either.
This tension between beauty and vulnerability comes up often in our consultations at Hochwert. How do you protect a material without changing its character? How do you preserve the patina, the texture, the finish that makes a natural stone unique — while still protecting it from everyday life?
An Afternoon Dedicated to a Shared Question
We're exploring exactly this question on Thursday, August 27, 2026, together with Hägni AG, experts in stone refinement, as part of a brownbag lunch hosted by the Swiss Baumuster-Centrale Zurich (SBCZ).
Under the title "KONKRET – On a Molecular Level," we're inviting professionals from architecture, design, and construction to join us in exploring protective solutions for natural stone and cementitious surfaces. It's exactly the kind of event we value most at Hochwert: grounded in expertise, hands-on, and carried by a community that approaches materials with the same care we do.
Marc Sommer, natural stone expert and director of the Hochwert Library, opens the afternoon with an introduction to the petrological properties of natural stone — the scientific foundation explaining why different stone types behave so differently. Following his talk, Remo Hägni and Guido Walliser of Hägni AG take over to introduce a solution that is genuinely new in its approach.
RAKU: Protection You Can't See
At the center of the afternoon is RAKU, a new anti-acid system that differs fundamentally from conventional sealants. While standard solutions simply create a layer on top of the surface, RAKU works directly on a molecular level — deep within the material itself, rather than merely on its surface.
The result: lasting protection against acid stains, without altering the stone's color, sheen, or texture. The application is suitable for both new and existing calcareous surfaces, as well as polished cementitious surfaces. Because the product acts as an invisible barrier within the material rather than an external coating, it is also UV-resistant, heat-stable, and won't yellow over time.
For us at Hochwert Library, this marks a meaningful step forward: a solution that lets natural stone remain exactly as it is — with no compromise on aesthetics or feel.
Experience It, Don't Just Hear About It
What makes this event stand out is the chance to experience what you've just learned, firsthand. All visitors are invited to bring their own material samples to have them treated with the anti-acid system after the presentations — and test the effect themselves, on the spot. Specific requirements for material samples are listed on the SBCZ website.
This is the same spirit that shapes our work at the Hochwert Library: materials aren't understood through explanation alone, but through direct experience — the texture under your fingers, the surface's reaction, the difference you only truly see once you've brought it about yourself.
Free Admission, Registration Required
Participation in the brownbag lunch is free of charge. Registration is open until August 25, 2026, via the Swiss Baumuster-Centrale Zurich website or by QR code.
Event Overview:
Title: KONKRET – Brownbag Lunch "On a Molecular Level"
Date: Thursday, August 27, 2026
Time: 12:15 – 1:15 PM
Location: Schweizer Baumuster-Centrale Zürich, Hohlstrasse 420, 8048 Zurich
Speakers: Marc Sommer (Hochwert Library), Guido Walliser & Remo Hägni (Hägni AG)
Cost: Free
Registration: by August 25, 2026, via baumuster.ch
We look forward to exploring, together with Hägni AG and the Swiss Baumuster-Centrale Zurich, a question that has always mattered to us at Hochwert: how to not only select high-quality materials, but to preserve them, too. We warmly invite you to join us — and to bring your own material samples along.
Learn more about Hägni AG and their work in stone refinement at haegni.ch.