Investigation Of Cat Scratches On Container Glass

Cat scratches have become a chronic quality problem for the container glass industry but there is still controversy about their origin and how to eliminate them. Many tests related to appearance, shape, location, and chemical composition of this type of cord have therefore been made. As a result, it can now be said that cat scratches are surface cords containing higher amounts of alumina and especially zirconia than the host glass. The cords form 10-20um thick bands located 10-60um below the surface. The origin of the problem is the corrosion of refractory material. It is impossible to locate exactly the primary source because different mechanisms can create the cords. However, the main source is probably in the hot zone of the melter.