Glasfehler des Monats

August, 2019
Rusted Butterfly
During container manufacture, molten glass is blown out into molds using pressurized air. Contaminants in the air supply, such as the particle of rust shown here, can become embedded on the inside surface of the newly formed bottle. In this SEM micrograph, the bubbles and dissolved metal stretched into the surrounding glass suggests that the rust particle was deposited during blowing out of the parison (i.e. blank). The interesting pattern was created when embedded material was distorted by expansion in the blow mold.
July, 2019
Toxic Swirl
This iron stone has reacted with the surrounding glass, creating a telltale greenish-brown swirl. Bottle caps and lids are a possible source of iron contamination in recycled cullet, but the use of magnetic separation usually prevents widespread problems from occurring. The internal cullet supply can be more vulnerable, however, and nuts, bolts, wire, or even mold parts have been known to find their way into the furnace.
June, 2019
Spring has arrived here in Western Pennsylvania and the birds are chirping and flying branch to branch. However, they cannot land on this “Birdswing” as it was found in the neck of a glass bottle. This critical glass defect is actually a thin strand of glass stretched between two points on the inside surface of a bottle. It is caused due to low viscosity of the glass, when the opposite inside surface touch, causing them to fuse. During the blowing out of the parison into the final shape a filament will be drawn between the points where the opposite inside surfaces made contact. The thin glass strand poses a risk for breakage during filling or use, which would create glass-in-product.
May, 2019
This month we are featuring a Scanning Electron Microscope (SEM) view of an open check/tear on the outside surface of a glass container. You would be excused, of course, if a quick glance led you believe this was an image of butterfly sitting on a mirrored surface.
April, 2019
Reptilian Eye
While staring at this month’s unblinking defect might give you the chills, it actually is an alumina silicate stone within a viscous solution sack formed from a dissolving stone. It was found buried in the surface of a glass container and caused by a ceramic contaminant in the cullet stream.