The Portland Vase is one of the prized possessions of the British Museum and is a stunning work of art that attracts many people who tour British Museum. There are many theories on the origin of this beautiful vase. Richard Whiteley, who is an Associate Professor from the Australian National University School of Art and Design, recently said that all the previous theories on the origin of the 2000-year-old artifact are wrong. He also claimed that he has evidence to prove a more likely explanation on how the vase was made.
The Portland Vase is not very big and measures only 25 cm high and 56 cm around the widest part. However, the craftsmanship and artistry that went into the making of the vase are really surprising and can stop even the most casual museum visitor in front of it like a brick wall. It is said that the Portland Vase could not be duplicated for more than 1,700 years because its manufacturing secret was long lost.
Historians say that the vase was made around 25 AD, which was a period of experimentation in cameo glass by the Roman glass blowers. The vase has a dark blue glass body with finely carved white glass layer on top. The layer of carved white glass covers the lower half portion of the Portland Vase. The outer layer of the vase is carved in detail and displays six people, a snake, and cherubim in a garden landscape. However, there are no details on the history, origin, or purpose of the Portland Vase that was discovered in Italy in the sixteenth century.
For many centuries, the vase was considered the premiere example of Roman cameo glass that is manufactured making used of a very advanced technique making it impossible for anyone to duplicate it. The challenge was so big that in the nineteenth century a prize of 1,000 pounds was offered to any person capable of cracking the secret behind the manufacture of the vase. This contest was won in 3 years by a glassmaker named Philip Pargeter.
The general method that was used to make Portland Vase was to blow a bubble of blue glass and dipping it in a vat of molten white glass, while the blue glass is still very hot. However, many still doubt if the vase is actually a work of blown cameo glass. As per Whiteley, the cameo glass might not be blown but made with a cold pressing method that is usually called pate de verre. In the method, glass is finely powdered and mixed with usual binding agents like gum arabic and water. After mixing, it is pressed into a mold, the mixture is heated until the glass melts and takes the shape of the mold.
Whiteley said that by examining a piece of Roman cameo glass under a CT scanner, he could see the direction, composition, and pattern of the air bubbles trapped between the white and blue layers of glass. He found that the shape of the bubbles were not same as that seen in blown glass.
“We saw a bubble configuration within the glass that results from a pressing and turning motion,” said Whiteley. “I believe that cold granulated glass has been packed into a mold and then a blob of molten blue glass introduced and pressed against mold heating the white granules from behind. You just would not get a bubble that size and flat-shaped from blowing. The most striking thing about it, is not its size and its flatness, but we found a section where the blue glass has mixed with the granulated white specks of glass.”