Iridescent glass oinochoe, Syria, 300-400 AD

Iridescent glass oinochoe, Syria, 300-400 AD
Period:
Dating:300 AD–400 AD
Origin:Roman World, Eastern Roman World, Roman Syria
Material:Glass (all types)
Physical:10.1cm. (3.9 in.) - 40 g. (1.4 oz.)
Catalog:GLS.MM.00682

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Links to others of type Oinochoe

Blue glass oinochoe, Roman, 1-100 AD
Glass oinochoe, Syria, 200-400 AD
Glass oinochoe, Syria, 200-400 AD
Glass oinochoe, Syria, 300-400 AD
Glass oinochoe, Syria, 300-400 AD
Iridescent glass oinochoe, 20 BC-100 AD
Iridescent glass oinochoe, Syria, 200-400 AD
Iridescent glass oinochoe, Syria, 200-400 AD
Iridescent glass oinochoe, Syria, 200-400 AD
Iridescent glass oinochoe, Syria, 300-400 AD
Iridescent Oinochoe, Syria, 300-400 AD
Iridescent oinochoe, Syria, 300-400 AD
Iridescent oinochoe, Syria, 50-350 AD
Iridescent olpe, Roman, 100-300 AD
Iridescent olpe, Syro-Palestine, 100-300 AD
Pottery oinochoe, Greece, 550-500 BC
Trefoil mouth oinochoe, Roman, 75-250 AD
Trefoil mouth oinochoe, Syria, 200-400 AD
Trefoil mouth oinochoe, Syria, 200-400 AD
  Beneath the spectacular iridescent coat of this delicate Oinochoe, the glass is transparent pale blue. The bottom is flat, with a prominent pontil mark, the body is pyriform with a smooth transition to a tapering neck, and a flaring mouth with an infolded rim. The thin and wide ribbon handle presents a large attachment point mid-body, stretching almost directly to the rim where the extra material was gathered, then snapped off. Probably from Syria, Eastern Roman World, 300-400 AD.

Oinochoe
An Oinochoie (sometimes spelled Oenochoe) is a “Jug with an ovoid body, a vertical loop handle, a flat base, and usually a trefoil (pinched) lip. Examples occur in many shapes and sizes, some having a circular mouth, a beaked lip, or a spout. There are two types:(1) with the neck set off from the shoulder; and (2) with a continuous curve from the neck to the body (the olpe is a form of this type)… There are glass oenochoe of small size (4 to 9 cm.) used as receptacles for toilet preparations…” (Newman 1977).

Glass Iridescence
The iridescent effect that so often enhances immeasurably the beauty of ancient glass was not planned by ancient glass artisans. Instead, it is the combined result of weathering processes and the properties of light. The rainbow effect you commonly experience in daily life, such as on soap bubbles or drops of oil spread on water, stem from the same action: light bouncing on a extremely thin transparent film.

When a glass bottle is new, there is no such thin film. The wall of the bottle is homogenous. But “as glass is exposed to water in its burial environment, some of its [chemical] components can be dissolved by the water and carried away (leached out). This generates a thin surface layer of glass that has a different composition that the undegraded bulk of glass. Often, there is a think layer of air between the corroded surface and the bulk” (Bezúr 1999).

When ordinary white light strikes the bottle, some of the rays bounce off the top surface of the thin film, and some go through the thin film and then bounce off the glass-air interface between the thin film and the underlying glass. When the rays coming back from the bottom of the thin film reemerge into open air, they combine with those that simply bounced off the surface. But since they have been delayed by their additional travel, their waves are no longer in phase (in synch). When these two streams of out-of-phase white light combine, some of the wavelengths cancel out (and therefore those colors disappear), and other wavelengths are reinforced (and therefore those colors become very intense), thus turning white light into vivid random colors.

Glass artists of the late 19th Century, such as Louis Comfort Tiffany, admired the iridescence of Roman glass, and devised ways to produce it deliberately by placing the glass piece while still very hot in an oven filled with vapors (tin and iron chlorides) that would alter the surface and create a thin film of different composition, yielding an iridescent effect that did not require a thousand years to develop.

A more thorough technical discussion of the phenomenon by Aniko Bezúr of the University of Arizona Department of Materials Science and Engineering is available from http://www.u.arizona.edu/ic/mse257/class_notes/iridescence.pdf

Miniature Glass Jugs
Miniature glass jugs “are usually made of various hues of blue glass with varying degrees of translucence, sometimes appearing nearly black. Like rod-formed vessels, the miniature jugs were not blown, but tooled by bead makers… Juglets are thought to have been amulets… The shape of the miniature jugs may have been meant to evoke a specific contents, for example holy water from one of the many pilgrim sites. If the hypothesis that miniature vessels were Christian amulets is correct, this might provide an explanation for their unusual distribution pattern from the Eastern Mediterranean to western Europe… Miniature jugs may have been sold as souvenirs or amulets. The custom of taking relics and souvenirs from holy places appears to have been well established by the sixth century… Type II occurs not only in Palestine, especially in Galilee, but also in Egypt, the western Mediterranean, and northwest Europe” (Stern 2001:361).

Bibliography (on Oinochoe)

Newman, Harold
1977 An Illustrated Dictionary of Glass. Thames and Hudson, London, UK.



Bibliography (on Glass Iridescence)

Bezur, Aniko
1999 Online Notes on Iridescence (http://www.u.arizona.edu/ic/mse257/class_notes/iridescence.pdf). University of Arizona, Department of Materials Science and Engineering, Tucson, AZ.



Bibliography (on Miniature Glass Jugs)

Stern, E. Marianne
2001 Roman, Byzantine, and Early Medieval Glass; 10 BCE-700 CE; Ernesto Wolf Collection. Hatje Cantz Publishers, Ostfildern-Ruit, Germany.






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