Fourcault process the pit must be "heated back" and then the process can continue anew. Glass chemistry has a huge impact on the process since it controls the melting, forming and annealing temperatures, liquidus temperature (point where various chemicals that make up the glass start to crystallize out of the glass) and rates of change of characteristics of the glass itself. Occasionally the ribbon will break or crack, leading to failure of the drawing process. Such breaks, known as "checks" can be alleviated by using proper operating parameters. Sometimes an expedient measure, using a portable source of heat, can be used to
Shaping processes in crystal growth Shaping processes in crystal growth Shaping processes in crystal growth are a collection of techniques for growing bulk crystals of a defined shape from a melt, usually by constraining the shape of the liquid meniscus by means of a mechanical shaper. Crystals are commonly grown as fibers, solid cylinders, hollow cylinders (or tubes), and sheets (or plates). More complex shapes such as tubes with a complex cross section, and domes have also been produced. Using a shaping process can produce a near net shape crystal and reduce the manufacturing cost for crystals which are composed of very expensive or difficult