For centuries, bubbles resulting from an imperfect fusion or poor refining have been the glassmakers' nightmare. Trapped in the matter, they are a sign that the temperature has not been kept high enough for the required duration to allow the fusion gases to escape to the surface of the glass bath. This malfin glass, therefore, constitutes a failing glass whose effect the Verrerie de Biot has taken advantage of and has voluntarily reproduced. It also is an ancestral technique used in the manufacture of lighting by glassworks from Scandinavia, Venice, or Bohemia.