The Magic of Striking

Preciosa’s latest color innovation, Rose Peach, is among the most challenging to get right; not just for Preciosa, but for the entire glassmaking industry.

crystal color Rose Peach blanks after striking

Rose Peach blanks after striking, ready for cutting.

The color mixture contains 24-karat gold and silver, and must undergo the complex and highly specialized process of “striking” to achieve its perfect rosy-pink hue. While some glass colors, like Crystal or Cobalt Blue, emerge from the furnace looking like Crystal or Cobalt Blue, others emerge looking nothing like the name on the production sheet. These colors require a carefully controlled series of heating and cooling cycles – known as striking – that effectively change the color of the glass after it has been produced. If this sounds complicated, that’s because it is. Simply put, striking activates the metallic compounds found within the glass mixture, creating a chain reaction that transforms its chemical makeup. This transformation alters the way light interacts with the glass, resulting in a change in color.

The process

“Exact times and temperatures depend on the present compounds, desired color and stone size,” explains Milan Pátek, chief technologist at Preciosa’s glassworks in Prysk. “This information, along with our many glass recipes – we have around 3,800 – are closely guarded trade secrets, known in full by only three people in the factory.” Although the glass is re-heated, it is not re-melted. At this stage, the glass is already in the form of what is referred to as the “blank.” A blank is an intermediate or partially finished piece of glass that will undergo further processing – it already resembles its basic shape but is not fully shaped: cut, polished or finished. The blank is first cooled to a hardened state, then placed in an oven heated to several hundred degrees. “Colors that require a higher temperature are covered in layers of clay to protect against deformation or re-melting,” explains Mr. Pátek. “Re-heating is a highly specialized process with many variables, leaving lots of opportunities for error.”

New color Rose Peach on Chaton Roses MAXIMA and Rondelle Beads.

Variegation refers to an irregularity or inconsistency in the color or appearance of the glass. If there is variegation in the blanks, uneven streaks can appear after the glassis struck, or larger sizes with holes can even crack due to repeated stress. “Although this is a rare occurrence owing to the high level of professionalism at our glassworks, errors can still happen,” says Mr. Pátek. “There are no second chances – you have to get it right the first time or the blank has to be completely remelted down and used in another batch of the same color. Mastering the industrial production of Rose Peach was a real challenge,” he adds. “We cannot wait to see this new shade on the luxury items and catwalks Preciosa is relied on to illuminate.”