Iridescent glass flask, Syria, 300-400 AD

Iridescent glass flask, Syria, 300-400 AD
Dating:300 AD–400 AD
Origin:Roman World, Eastern Roman World, Roman Syria
Material:Glass (all types)
Physical:10.6cm. (4.1 in.) - 30 g. (1.1 oz.)

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Links to others of type Flask

Biconical glass flask, Syria, 200-400 AD
Cylindrical glass bottle, Syria, 300-400 AD
Diamond-pattern blown glass flask, Rome
Double-head glass flask, Syria, 1-300 AD
Flattened glass flask, Syria, 1-300 AD
Flattened traveller’s glass flask, 50-120 AD
Glass flask, Eastern Roman, 280-350 AD
Glass flask, tooled stemmed foot
Glass unguentarium, Alexandria, 1-100 AD
Glass unguentarium, Roman, 50-150 AD
Glass unguentarium, Syria, 1-100 AD
Golden iridescent flask, Syria, 300-400 AD
Iridescent funnel-mouth flask, Palestine
Iridescent glass flask, Palestine, 40 BC-30 AD
Iridescent glass flask, Roman, 1-200 AD
Iridescent glass flask, Roman, 1-200 AD
Iridescent glass unguentarium, 1-100 AD
Iridescent glass unguentarium, 1-100 AD
Iridescent glass unguentarium, 1-100 AD
Iridescent glass unguentarium, 1-100 AD
Large flat glass bottle, Syria, 1-100 AD
Mold-blown glass flask
New year flask, royal gift of sacred water
New Year’s flask for sacred water, Dyn.18
Polychrome glass flask with spiral coil
Spherical glass flask, Palestine, 200-700 AD
Translucent glass flask
Translucent glass flask, Palestine 600-700 AD
  Beneath its magnificent iridescent coat, this glass unguentarium was blown of very pale green glass. The flaring mouth transitions smoothly to an unusually long straight neck, which meets the body with a sharp indent (although this is not a sprinkler flask). The body is hemispherical, slightly irregular, with a kicked bottom. Roman world, 4th century.

Thick black weathering crust. Deep loss of material where flaked.

“Spherical sprinkler flask. Ht. 7.8 cm. Colorless glass with a greenish tinge. The sprinkler flask has a roughly spherical body blown in a bipartite mold decorated with a stylized vine scroll or herringbone pattern. A constriction ring is present at the base of the neck. The piece is covered with thick dark weathering product flaking away to reveal fiery brilliant iridescence. Eastern Roman Empire or Byzantine, 3rd. - 5th. century AD” (Fortuna 1991:63 #108).

“Ribbed flask. Ht. 12.4 cm. Yellowish-green glass. Spherical flask with a tubular neck and flared infolded lip resting on a concave bottom. The piece is decorated with unevenly distributed vertical ribbing, probably produced by tooling rather than pattern molding. Multicolored iridescence and dark encrustation in some sections. Eastern Roman Empire, 3rd. - 4th. century AD” (Fortuna 1991:60 #98).

“Gutturnium. Ht. 10.2 cm. Syria, 3rd. - 4th. century AD” (Münzen und Medaillen 1986:21-22 #73).

“The earliest shape to be blown, the bulbous bottle with a tubular neck, was made throughout the Roman empire… This general purpose bottle, probably known as ampulla in antiquity, was made in a wide range of sizes. Small ampullae are called unguentaria or balsamaria in modern terminology after the contents which were often unguents or ointments, but the bottles were also used for scented oils, cosmetics, pigments, salves, medicines, and even dried herbs. The bulbous bottle was simply the simplest shape to blow because it needed very little tooling. The glassblower could make a spherical, piriform, or tubular bottle without touching the glass. The rim could be finished by reheating: the simple action of rotation caused the rim to flare outward and the edge to fold over” (Stern 2001:43).

“A small receptacle for toilet preparations (e.g.: oil, scent, kohl). They were made of glass in numerous sizes (usually from 3 to 16 cm. high) and forms. Some examples made of core glass are in the form of various types of Greek vases (e.g. aryballlos, alabastron, lekythos, ampulla) and have combed decoration. Others of the Roman period were of coloured or colorless glass and were of spherical or conical shape, with a slender neck… Many such objects were deposited in Roman tombs, mistakenly thought to have been used to hold tears of the mourners, and were sometimes called ‘tear bottles’ or ‘lachrymatories’… also called a balsamarium.” (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

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 (for this item)

Fortuna Fine Arts, Ltd.,
1991 Shining Vessels: Ancient Glass from Greek, Roman, and Islamic Times. Fortuna Fine Arts, Ltd., New York, NY. (63 # 108

60 # 98)

Münzen und Medaillen,
1986 Auktion 70. Kunswerke der Antike. Münzen und Medaillen, Basel, Swizerland. (21-22 # 73)

Bibliography (on Unguentarium)

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

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

Bibliography (on Glass Iridescence)

Bezur, Aniko
1999 Online Notes on Iridescence ( 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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