Excavations at Cologne in the Rhineland suggest that there was a glasshouse here quite early in the first century AD. It was perhaps founded in AD 50 when the emperor Claudius (AD 41-54) made the town a colony at the request of his wife, Agrippina the Younger. This flask has an opaque yellow spiral trail on the neck between the handles, as well as single opaque yellow trails above and below the pattern of tooled and milled snake-thread trails. 'Snake-thread' trails take their name from their appearance. Most vessels with this type of trailing date from the third century AD. The technique seems to have been introduced from the east, where the vessels of greenish or colourless (clear) glass are normally decorated with trails of the same colour as the body. The examples from the Rhineland usually, but not always, have trails of different colours to the body, as on this example. The flask has been broken and mended, and the foot-stand is missing.