Spicules are tiny glass flakes which are formed during the manufacture of
glass
Glass is a non-crystalline, often transparent, amorphous solid that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass is most often formed by rapid cooling ( quenching ...
vial
A vial (also known as a phial or flacon) is a small glass or plastic vessel or bottle, often used to store medication as liquids, powders or capsules. They can also be used as scientific sample vessels; for instance, in autosampler devices i ...
s. A glass tube is extruded at a constant rate and a jet of water applied to the hot glass is used to cut the blank tube to length. The bottom and lip of the vial are formed by swagging or upset forming while the glass is still hot.
Spicules are formed in a cloud when the glass explodes from the contact of the cold jet. These are held to the glass blank during forming, and if the vial is not reheated or cleaned after manufacture, these spicules can drift off into the mixture subsequently placed in the vial. This is a serious problem in the manufacture of soft
contact lenses or pharmaceutical products.
Glass engineering and science
{{Glass-engineering-stub