Ketonen discovered his own technique — Graal — during his on-the-job training periods in Riihimäki. In graal, several layers of colored glass are blown into a blank. After cooling, the surface is engraved or painted with images, and the blank is reheated and encased in clear glass. The thick mass acts like an optical lens that brings the imagery to life.

During his studies, Ketonen completed every module of his professional qualification specifically through the stages of graal. He wanted to master the technique thoroughly — and above all to adapt it to his own artistic expression.

Developed in the 1910s in Orrefors, graal is relatively young in the history of glass art, and according to Ketonen, it still holds vast, unexplored potential. For him, a technique is an open field where fearless experimentation matters as much as following tradition.

“If someone says, ‘You can’t do it that way,’ that’s usually a sign I should do it exactly that way. When I repeat what looks like a mistake, it becomes a method—a tool that helps me make the piece look the way I want.”
 

Unlike traditional Graal practice, Ketonen deliberately allows the color layers to blend and react with one another. His greatest inspiration comes from the interplay of color and optics, and from the way light interacts with the glass.
Another characteristic feature of Ketonen’s work is its organic form language. He uses tools sparingly—allowing hot glass to find its shape through gravity, rotation, and movement.

“I can create purer, more natural forms when I don’t force the glass with tools.”