Window glass thickness dating technique

Usually when a liquid is cooled to below its melting point, crystals form and it solidifies; but sometimes it can become and remain liquid below its melting point because there are no nucleation sites to initiate the crystallisation.If the viscosity rises enough as it is cooled further, it may never crystallise.The viscosity rises rapidly and continuously, forming a thick syrup and eventually an amorphous solid.The molecules then have a disordered arrangement, but sufficient cohesion to maintain some rigidity.

It is sometimes said that glass is therefore neither a liquid nor a solid.In principle, a glass could undergo a spontaneous transition to a crystalline solid at any time.Sometimes old glass devitrifies in this way if it has impurities.The transition can be detected as a marked change in the thermal expansivity and heat capacity of the material.The temperature at which the glass transition takes place can vary according to how slowly the material cools.

Leave a Reply

  1. who is brendon urie currently dating 30-Mar-2020 11:13

    While filmmakers such as Michel Auder, Jonas Mekas and Ed Pincus created cinematic diaries, the sculptor Claes Oldenburg, in the early 1960s, had theatrical showings of his home movies.