Glass quality and glass defects

Defects and inclusions

We are experts in analysing inclusions in glass, such as blisters, stones or cords. In dialogue with the glassmaker, we can find the cause, which can be linked, for example, to raw materials, glass recipes, corrosion on the furnace material or to the manufacturing process. Any contaminants and discolouring substances are identified. We also investigate surface defects from contact with moulds and tools. Other examples are problems with scratches in the glass surface and delamination of flat glass.

Surface attack

Glass is a chemically resistant material but can still be attacked under certain conditions. We investigate and analyse weathering, corrosion and deposits on glass, such as stains from concrete drainage on windows and facades. We test how many times household glasses can be dish washed in a machine before they become milky white in the surface. We also have experience of archaeological glass and glass that has been affected by so-called glass disease.

Breakage

When glass breaks, we can investigate the cause, which can be related, for example, to defects, mechanical impact, improper fixation, incorrect annealing process. We can assess and measure residual stresses in glass and calculate the annealing procedure for a safe glass with low residual stresses. When different glasses are to be combined and fused together, we can determine the tension between clear glass and coloured glass and modify the glass recipes so that the glasses match in expansion. For thermally strengthened flat glass, we can check the degree of tempering. We also investigate suspected spontaneous granulation of tempered glass for windows, facades, shower walls, glass panels. If unknown glass fragments have ended up in food, for example, we can also help find the source.

Important analytical techniques are optical microscopy, scanning electron microscopy (SEM / EDS), polariscope, scattered light polariscope (Scalp), nanoindentation and optical profilometry.