Défaut du mois

November, 2021
Blue Worm
This wormlike flaw is actually classified as a type of stone resulting from AZS refractory erosion that drips into the melt. Typically AZS drip stones are composed of very small particles of zirconia that are embedded in nepheline and/or carnegeite. They are produced by decomposition of the AZS refractories in the superstructure or run-down of molten silica over AZS refractories. AZS stones should not be returned to the cullet stream as they are unlikely to melt in subsequent trips through the furnace.
June, 2021
A deadly viper or a piece of lint fiber? To some, both possibilities in or on your glass container may be equally horrifying. This SEM image of a crinkled fiber viewed at 330x demonstrates the importance of experience in knowing what to look for. Contaminants such as weathering can adopt unusual geometries that can be confused with surface debris, and particles filtered from product can occur in almost any material or shape. We have even analyzed contaminants ranging from rodent dung, to machine oil, to blood.
May, 2021
Unfilled Finish
Have you ever started a home-improvement project, but stopped because you ran out of materials? The defect in this picture is a little bit like a partially completed project and is referred to as an ‘unfilled finish.’ It occurs when the glass weight is too low and there isn’t enough glass left to fully form the finish. This type of defect prevents the bottle from being capped.
April, 2021
Butterflies in the sun
The picture was taken at 100x magnification in a polarizing microscope with a first order red insert. This is a stone that exhibits bright birefringence with crystals of zirconia at angles that are reminiscent of butterflies in flight. The stone is a melted viscous layer of a AZS refractory that dropped into the molten glass from above the flux line. Once surrounded by the molten glass it experienced comparatively cooler temperatures and the droplet recrystallized to form six sided crystals. The melting of AZS refractory that led to the stone creation had been caused by batch dusting and/or misdirected burners causing spikes in furnace temperature.
March, 2021
Egyptian necklace
Traditional necklaces of ancient Egypt incorporated parallel rows of beads, creating heavy concentric bands around the wearer’s neck. This image of a fracture origin presents a similar effect. Pronounced ripple markings on the fracture surface, such as those on this sample, are a hallmark of point contact damage. As the name suggests, point contact damage is caused by forceful contact with a hard, pointed object. This particular origin was found on the sealing surface of a bottle, and analysis via SEM-EDX revealed glass-to-glass damage nearby.