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
Spin glass as the sample is cooled to the transition temperature, magnetization of the sample increases as described by the Curie law. Upon reaching "T", the sample becomes a spin glass and further cooling results in little change in magnetization. This is referred to as the "field-cooled" magnetization. When the external magnetic field is removed, the magnetization of the spin glass falls rapidly to a lower value known as the "remanent" magnetization. Magnetization then decays slowly as it approaches zero (or some small fraction of the original value—this remains unknown). This decay is non-exponential and no simple function can fit the curve