The 1930s-1950s were a period of experimentation with glass and light. In February 1934, Crotti gave a lecture at the Centre d’études des problèmes humains on the theme of “Shapes and colors in motion”. During this lecture, equipped with a magic lantern, he projected colored translucent materials onto a screen. This innovative experiment heralded the development of “gemmail”, a new lead-free stained-glass technique for which he filed a patent.

In 1937, he presented “Kalocolor Projections”, a system of light projections through transparent, colored bodies, then distorted by various sets of lenses at varying distances from each other, using the zoom principle to create an infinite stained-glass window in perpetual mutation.