Defect van de Maand

October, 2020
Flying Bug
This summer in Western Pennsylvania we have had to contend with mosquitos, flies, bees, hornets, and now these flying bugs. The bug-like inclusion shown here is a common crystalline devitrification stone called Beta Wollastonite. Wollastonite is composed of calcium silicate and will form in cooler areas of the furnace and forehearth. It typically crystallizes into large prisms that produce vivid retardation colors in polarized light. These types of stones will not melt in molten glass and thus the cullet containing these stones should not be re-introduced into the batch.
September, 2020
This sea green stone actually started as a grass-green colorant. Chromic oxide, is a batch additive used to make green glass. It can form inclusions due to insufficient melting or mixing. Excessive moisture or humidity may have caused it to agglomerate. Chromic oxide stones are difficult to melt and therefore should not be returned to the cullet supply.
August, 2020
Nazca Desert Drawings
In the Kingdom of the Crystal Skull, Indiana Jones used (real) giant desert drawings to locate the (fictional) city of Akator. The unusual markings at the fracture origin shown here bear an eerie resemblance to the drawings created by the Nazcas, and are similarly shrouded in mystery. This particular origin was found at the inside knuckle of a glass container along with embedded material. Elemental analysis showed that the metal particulate was composed primarily of nickel and iron, likely caused by degradation of the plunger.
July, 2020
Bottle Opener
This crescent-shaped fracture typically occurs on bottles with a crown closure. Bottles broken during opening usually have a C-shaped fragment missing from the locking ring. This fracture pattern is usually caused when the consumer accidentally makes contact with the underside of the locking ring of the bottle with an opener rather than engaging just the cap.
June, 2020
Finish Line
This photomicrograph shows a top-down view of the sealing surface on a bottle. Three percussion cone flaws can be seen, of which one has extended into a crack across the finish. These percussion cones were caused by downward-directed impacts from a blunt object with a relatively small radius.