Anisotropy is caused by stress differences in the glass which result from uneaven heating and cooling of the glass in the tempering process. The phenomenon becomes visible when glass is viewed in polarized light – which is why anisotropy is especially visible for example when glass is installed by seaside or high in the mountains. In certain conditions anisotropy can become visible other venues as well.
Anisotropy is first and foremost a visual defect and it does not make glass weaker from a mechanical point of view. Laws, regulations and standards define requirements for safety glass regarding it’s mechanical strength. Hence, anisotropy is traditionally not considered as a defect from a regulatory point of view. However, anisotropy can effectively ruin a facade’s appearance, which is why it should not be overlooked. A key factor here is also measurement technology that hasn’t been able to provide reliable and fast measurements of all processed glasses.
Taking control of anisotropy has been a continuous headache for glass processors. By using latest machinery and technology it is possible to get better results regarding anisotropy – and solutions for controlling anisotropy are getting more and more sophisticated. In this session we will take a look of how anisotropy can be controlled and measured with latest technology.