Roman glas bottles, 2-3 AD.
© Science Museum / Science & Society Picture Library
The bottles' long necks are a product of the blowing technique used to make them. By dipping a blowpipe into molten mixture, a glasmaker could then mould the mixture into a variety of shapes. The Romans were one of the first cultures to manufacture glas. Having mixed sand with other ingredients, the glasmakers would then heat this 'batch' in a furnace, and as it cooled the glas was formed.