Sand transformed
Archaeologist Ticia Verveer on Facebook:
These lovely glass birds contained cosmetics in powder form, to which access was gained by breaking the end of the bird’s tail. This type of powder container was made by glassblowing, a technique perfected circa 50 BC by Roman glassworkers in the eastern Mediterranean region.
Production of these small glass birds was particularly abundant during the reign of Emperor Augustus (27 BC-AD 14) and was still quite popular until circa AD 70.
Although many such birds have been found in Greece, Cyprus, and Syria, northern Italy (particularly Piedmont) and the canton of Ticino in modern Switzerland seem to have been the principal region for the production and distribution of this type of container.
H/t Vanina
Incredible. The fact that four of them have survived almost perfectly intact for two thousand years is made all the more surprising when one sees on the two damaged birds how thin and delicate the glass is.
Untempered glass almost always breaks spontaneously. Uneven cooling leaves extreme stresses on the material. Unless the powders were immune to heat, it would be incredibly difficult to make these birds last until the consumer chose to break them open.
John, it’s likely that the tails were left as open tubes for the tempering process, filled when cold, and finally the tip of the tail being re-heated enough using a tallow flame to enable the blower to pinch it closed and smooth it off. That would not only seal the vessel but also create a natural weak-spot, making it easier to open with a clean break and less likely to shatter.
The Romans also produced dichroic glass, ie glass that appeared red or green depending on the ambient lighting–an example of Roman nano-technology.
The green colour in Roman glass was largely accidental, caused by iron impurities in the raw materiels. However, the glassmakers knew that adding copper oxide to the molten ‘metal’ in a furnace with an oxidising atmosphere resulted in a stronger green colour, whilst adding the same oxide in a reducing (non-oxidising) atmosphere resulted in red glass.
By having two furnaces running, one with a smokeless fire which created oxidisation, the other smoky for a reducing atmosphere, they could add oxide to the metal in one furnace, allow it to melt and so become fixed into one colour, then transfer the cauldron to the second furnace and melt in more copper oxide. The result was a transparent glass with particles of both red and green copper in suspension, giving the dichroic effect.
That the glassmakers from as far back as the 10thC BCE were deliberately using various oxides to produce colour and knew that smoky or smokeless furnaces affected the colour achieved (though not understanding why), had to require much experimentation and ought to see the glassmakers, along with the first metallurgists, considered the first genuine scientists.
A of S @ 5
Very interesting. However I think that you’re stretching the definition of ‘scientist’ rather thin. Historically, technique, has until the 17th century, preceded understanding, so ‘not understanding why’ is exactly the point. Unless the early metallurgists and glass blowers had a coherent theory that they could test I wouldn’t describe them as scientists. I recently watched a doco on the production of late Medieval and early modern armor, the smiths developed remarkable levels of skills but they had no theory as why hammering the crap out of iron transformed it into steel. Also the Greek philosophers developed an atomic theory, they were correct, but they weren’t scientists.
I’d suggest Archimedes of Syracuse as the world’s first real scientist.
RJW, you’re right; ‘scientist’ is rather overstating things, it was more a successful alchemy, transmuting sand to glass and opaque minerals to transparent colours. It must have seemed like magic to the people of the time. There is very little that hasn’t been thrown into the mix at one time or another, even uranium in the early 20thC (to great effect, but only if seen in black light).
Glassmaking itself was a skill so revered that Renaissance-era Italian glass makers were ranked with the nobility, and throughout much of Europe at the time glass making was the only trade that an aristocrat could engage in without loss of rank, status, or privilege. Those in Lorraine, France, even enjoyed the same tax exemptions as nobility.
As you may have already guessed, the history of glass is a subject I am rather partial to.
Addendum to above; uranium was used in the first half of the 19thC in Germany and Bohemia, but only rarely and fell from fashion for a while until the 20thC revival when uranium itself became the ‘in thing’ and was being put into everything from toothpaste to condoms to paint for watch dials. It was a fashion that didn’t end well for a lot of people.
A of S @ 7 & 8
Yes, and there was even a children’s chemistry set on sale in 1951 that contained radioactive materials. After Hiroshima and Nagasaki it’s amazing how the horrendous effects of radiation were ignored.
Yes, you certainly are well-informed about glass production. I have a general interest in ancient techniques, alchemy is also a fascinating subject but for obvious reasons alchemists kept a low profile.
I knew about the exalted position of glass blowers, however I didn’t realise that aristocrats were involved in the industry. Metal smiths seemed to have stayed working class although they were held in very high esteem by the aristocracy for obvious reasons. In some regions and at various times the term ‘smith’ also meant ‘sorcerer’.
RJW, a radioactive chemistry set? Jesus! And I thought that being being given wads of asbestos to play around with in secondary school chemistry classes was a tad risky in retrospect.
It sheds a whole new light on those glowing children in the old Ready Brek adverts.
Re glassmaking:
In a book I am currently reading (The Crow Road, by Iain Banks), a glass factory figures in the storyline. At one point a character notes with amusement that, in the Dewey Decimal System, glassmaking is covered under category number 666. Seems appropriate.
They do say that the Devil’s in the details, Sackbut.