Islamic Blown Glass Vessel
Aelfgifu verch Morgan
What is it?
I based my design on a unique drinking vessel of probably Islamic origin, as well as other different vessels which contain similar characteristics. The most similar vessel is in the Kofler Collection. It is thought to be an example of the type of combined style possible when westerners were purchasing from local Islamic craftsmen. It contains attributes of both Islamic “donut” shaped bottles and the Anglo-Saxon and Frankish “claw beaker”. This sort of vessel was most likely used as a luxury drinking vessel.[1]
Drinking Vessel, Syrian region, Mid 13th century, Kofler collection.
Who owned it? How was it used?
It has been postulated that vessel in the Kofler Collection may have been owned by a Teutonic knight, a representative of the Order of the Hospitalers, or another Germanic crusader.[2] It is also possibly that this belonged to an Islamic person of the same time period (mid thirteenth century) and was simply inspired by the influx of outside design during the last period of occupation of the holy land by crusaders. Other Islamic vessels of the same time period contain non-Islamic imagery and are thought to have been possessed by locals.[3] One of the main reasons for suspecting that the specific extant vessel may have been owned by a crusader and then left in the holy land is the enameling which takes the form of an elongated shields shape on each of the “claws”. This type of shield is similar to the elongated kind used by some crusaders.[4] While this is true, there are certainly other examples of outside influences being incorporated into Islamic vessels and it does not constitute irrefutable evidence that this specific vessel would have been owned by an outsider to the region. I believe that the type of vessel I have made would either have been owned by a crusader or possibly by a wealthy local. While glass was certainly accessible to the middle class, this object is one of a kind and so was either a whim on the glass makers part, or commissioned by someone wealthy enough to request a special form. The fact that it also contains enameling, which was an additional and costly process supports the supposition that this belonged to someone who was either very wealthy or of the upper classes.[5]
The date on this object, mid thirteenth century, was attained by looking at the type of glass and enameling present on the claws. This sort of enameling was present mainly in the thirteenth and fourteenth centuries.[6] The shield shape of the design suggests crusader influence, pinning it down more closely to the last period of occupation of the holy land by crusaders.[7] It is also not as elaborately enameled as many of the fourteenth century examples of enameled Islamic glassware.[8]
The use of this object was most likely a decorative drinking vessel because of its wide mouth. While the only known parallels for the “donut” shape in the base are bottles and sprinklers, the wide mouth would make using this vessel as a long-term container impractical. It has been suggested that this sort of vessel may have been stored hung upside down by a string, chain or leather strap.[9] This is possible, but not necessarily true, as there were many Islamic vessels that did not have flat bases for storage. It would be possible for this sort of vessel to have a case, such as that enclosing the Luck of Edenhall, another vessel thought to have been owned by a crusader.[10] It may also have simply bee stored on its side or lip. It is uncertain weather this type of vessel may have been used during ceremonial occasions, or if it was simply a possession for private use in a persons own home because no similarly strange vessels appear in contemporary artwork.
Historical Context & Design Choices
I
chose to base my design almost entirely on the one extant example of this type
of vessel, that present in the Kofler collection. The key elements of this vessel are the donut
shaped base, the cup shaped top, and the hollow claws or tubes connecting the
two sections of the vessel. I chose to look at other vessels with similar
features in order to have a wider range of background material, and see
variations in individual features. Bottles with donut shaped bases were not unknown
in Islamic glass. Two such examples are shown below. The first example is a 12th
to 13th century Syrian sprinkler bottle of a solid blue color. It
has a blown foot.[11]
The second example is another perfume sprinkler, this one of two colors and
with little applied feet. It also dates to the 12th to 13th
century. While the pierced “donut” look was uncommon, other examples also exist
in collections in Duesseldorf and
Blue Blown Glass Sprinkler Bottle. Syrian, 12th
– 13th Century.
Blown Glass Perfume Sprinkler, Egyptian or Syrian, 12th
– 13th century.
Instead of making a vessel with no feet and a barely flattened bottom I chose to add on four little feet to the bottom of my vessel. Similar feet were used on various Islamic glass objects and they enhanced the ability to sit the vessel upright while not impacting the ability to hang it for storage if that was indeed the intended storage method for such vessels.
The other distinctive feature of this vessel, and that which makes it unique in Islamic art, are the claws or tubes extending from the cup to the donut section. While there are no other known medieval Islamic vessels with claws, the technique used to make them is the same as utilized in making the spouts on ewers.
Ewer, Iranian or
Mesopotamian region, 9th – 10th century,
Glass Tools and Techniques
The tools and techniques we use in glass blowing today are essentially the same type used in the Middle Ages. The basic tools of a glass blower include those used to actually melt and cool the glass and those used in forming it.
The tools used for heating and cooling are:
·
a furnace to melt and hold glass
·
a place to re-heat glass - either the mouth of
the furnace or an additional heating area modernly called a “glory hole”
·
An annealer to gradually cool off the finished
glass so it doesn’t crack while cooling.
There
are several different examples of medieval glass shops that can be observed in
pictures and from descriptions, and they all include these heating and cooling
tools. Unfortunately, while glass is available from most periods, all of the
pictures and descriptions of tools, furnaces, and techniques are from later
periods. 
Miniature of a float representing the glass guild
during festivities in
There are no known
Islamic texts dating from this time period which discuss the techniques of
glass blowing, nor are there any images from this exact time period. The
closest image is that above. This actually represents a float of the glass
bottle makers in
In, On Divers
Arts, written by Theophilus somewhere between the 10th and 12th
centuries CE, methods for creating a furnace for working glass and for making
an annealing furnace are described. [14]Another
example, similar to that shown on the Turkish picture, is from a description
and wood cut of a furnace from the Pirotechnia of Vannoccio Biringuccio: The
Classic Sixteenth-Century Treatise on Metals and Metallurgy. [15]
The Pirotechnia of Vannoccio Biringuccio. Furnace for melting, working, and annealing glass. Woodcut.
Other illustrations of medieval glass shops also include the same aspects – an annealer, a melt furnace, and a place to re-heat glass. As these are all necessary to the craft of glass blowing, it seems reasonable to assume that they would be part of any medieval glass shop. These furnaces were run off of wood, and fires were kept stoked by apprentices and workers who carefully watch the quality and heat of the fire. A modern glass shop such as the one where I made my glass consists of the same elements, but is run off of electricity and natural (or sometimes propane) gas for fuel, with regulators to do the jobs of the apprentices and workers.
The tools used for shaping the glass are:
- a blowpipe -on which to blow the glass
- a punty or pontile -on to which the glass vessel is transferred when it is time to open the mouth of the vessel
- a marver -a place to roll the glass to shape and cool it
- jacks -used for cutting in necks and pulling necks on bottles
- tweezers -used for pulling out bits of glass
- shears -used for cutting and trimming glass
These
tools can be seen in medieval illustrations in manuscripts. Here a glass blower
can be seen blowing through a pipe and marvering the bubble of glass on some
sort of flat surface. The same can be seen in the miniature of the
Depiction of a forest
glass shop from Sir John Mandeville’s
Travels, Dated 1420 – 1450. British
Library,
Tools and techniques have also been mentioned in descriptions. One particularly good description is from the The Pirotechnia of Vannoccio Biringuccio (pg. 130-131):
It (glass) is worked by being blown by men’s breath with certain iron tubes... With one of these they take the glass from the pot by attaching it to the point and then wrapping it around... and giving it the form of a large ball. The first thing they do after withdrawing it is to press it on marble, turning it over and over so that it unites. The blowing on it through the opening of the tube they make it like a bubble and they elongate it by swinging it about their heads... and finally, in short, they give it the form of the vessel which they wish by warming and blowing, by pressing and enlarging. Then separating it from the first tube they take hold of it again at the bottom with the other (tube) and improve it, cutting its mouth with a pair of shears...”
These are the same type of tools used today in glass blowing, and what I used in creating my glass.
Glass
Most
glass shops imported glass from other areas to use in furnaces. Usually glass
would be melted down into ingots near a source of materials, and then exported.
Then it would be crushed up into “cullet” to use in the glass furnace for
re-melting, occasionally raw materials would be shipped and combined in the
glass furnaces, and this is modernly called “batch”. Glass from failed attempts
which was not polluted by colored glass would usually be saved, crushed, and
re-melted in the form of “cullet”. Such glass was sometimes even exported from
places like
The
glass I use is one of the types of glass made in the Middle Ages. There were
three major kinds of medieval glass, pot-ash glass, soda-lime glass, and
high-lead glass. All three types of glass were used through the medieval world,
depending on what materials were available. The glass used in the shop where I
blow glass is soda-lime glass. The usual temperature for the working range of
medieval soda-lime and pot-ash glass was around 1800 - 2000 degrees Fahrenheit.
The glass I use is workable at temperatures between about 1900 and 2100 degrees
Fahrenheit. [19] [20]
Enamels & Gold
I have been experimenting with modern glass enamels in an attempt to get a Medieval Islamic look from them, and have just recently begun getting to the point where I am starting to get the look I desire. My most successful attempts have been using a clove oil based painting medium mixed with Reuche glass enamels. I mix the enamels to a very specific consistence where it will not run if left for several hours, but where, when possible, it is not so pasty that it leaves streaks when fired. I have been firing in an electric kiln up to 1050 degrees ferenheight and leaving the glass at that temperature for 30 minutes before lowering the temperature. There are no medieval Islamic texts discussing their techniques for enameling and gilding, which are very distinctive in style, so my enameling has been achieved mostly by trial and error. I recently found an article which gave break downs of the chemical compositions of various glass enamels, and at some future date I plan to begin trying to formulate my own enamels.
I attempted several different methods for gilding the glass. I originally tried simply laying a layer of gold leaf on the surface using egg white as a binding agent as described in, The Craftsman’s Handbook, for the gilding of gold ornaments.[21] I discovered that modern gold leaf is simply to thin to make this reasonable as the gold rubs off far too easily. I also tried the procedure with an especially thick silver leaf, and found that, while it was slightly more satisfactory, it was still not going to last well enough for use on a drinking vessel. My second method was using milled gold paint (in this case shell gold), letting it dry, and then painting enamel over the top, as discussed in Theophilus’, On Divers Arts.[22] This worked fairly well. As I do not have access to a clear enamel, I used a translucent amber yellow enamel which fires almost clear. I found that a very tick application of both gold and enamel were required for the gold to show up well and for the enamel to form a protective covering and keep the gold from rubbing off. I departed somewhat from the colors used on the vessel on the Kofler collection (red and blue) due to the fact that I was having varying degrees of success in having my red turn out red rather than a dark brown. I chose to use a green colored enamel as well on my final piece, as green is another color common to Islamic enameled glass of the 1300’s and 1400’s.[23]
Works Cited
Carboni, Stefano. Glass From Islamic Lands. Thames & Hudson in association with the
al-Sabah
Collection, Dar al-Athar al-Islamiyyah,
Carboni, Stefano, and David Whitehouse. Glass of the
Sultans. The Metropolitan
Museum,
Cennini, Cennino d’Andrea. The Craftsman’s Handbook; “Il
Libro dell’ Arte”.
Translated by Daniel V. Thompason,
Jr. Dover Publications, Inc.,
Jacoby, David. “Raw Materials for
the Glass Industries of
About 1370 – 1460.” Journal of Glass Studies. Vol. 35. Corning, New York.1993.
Smith, Cyril Stanley, Martha Teach
Gnudi (translated by). The Pirotechnia of Vannoccio
Biringuccio:
The Classic Sixteenth-Century Treatise on Metals and Metallurgy. Dover
Publications, Inc.
Tait, Hugh (ed.). Five Thousand
Years of Glass.
Theophilus On Divers Arts. Translated by John G. Hawthorne, Cyril Stanley Smith.
Dover
Publications, Inc.,
Toso, Gianfranco. Murano: a History of Glass. Arsenale Editrice. 2000.
Tyson, Rachel. Medieval Glass
Vessels Found in
British Archeology Report 121. 2000.