Fulgurite

Can glass be made by lightning striking sand like in Sweet Home Alabama?

Lightning can form glass if the lightning is 18000 degrees Celsius when it strikes silica. It forms a tube and takes about 1 second. The resulting glass is called fulgurite. The longest one found was 16 feet long. Glass can also be formed naturally by meteorite impact and volcanic activity.
Fulgurites have been used as jewelry since ancient times. Fulgurites also tell the story of the land. The Sahara Desert had many fulgurites showing that there must have been many lightning storms over the Sahara Desert. In Scotland a 250 million year old fulgurite was found that shows Scotland had deserts at that time.

(image via: Cristales Curativos)

Phoenician Glass Blowing

According to Pliny the Elder the first people to start making glass were the Phoenicians.
the invention of glass occurred on the Palestinian coast.

"He claimed that as natron merchants were sailing from Egypt, they brought their ships to shore at the mouth of the Belus River near Ptolemais. Lacking stones, they used some of their cargo to hold up their cooking pots. The heat from the fire caused the mixture of soda-rich natron and sand to fuse into glass" http://www.penn.museum/sites/roman%20glass/Glassmaking/glassmaking_intro.html

Though Pliny's explanation of how glass was first made is impossible the Phoenicians did have an important role in glass manufacturing. In 50 BCE the Phoenicians started using thin hollow glass rods to blow glass. The first evidence of blown glass ( Glass tubes Rods and small bottles) was found in Jerusalem.  This was a big step forward and the technology has not changed that much since that time. Glass blowing was started during the Roman Empire and because of this spread throughout the Roman Empire. After the Roman Empire glass making almost disappeared until revived in Venice in the thirteenth century.

Glassmaking in Egypt

The Video above explains the use of furnaces the make glass in Ancient Egypt. Glass was highly valued in Egypt. Its value was on the level of gemstones and gold. It was used as a diplomatic currency, giving it to foreign governors. For a long time it was thought the Egyptians imported their glass. In 2003 in Quantir  evidence confirmed that Egypt had their own thriving glass industry. What is the reason that no record was left of the glassmaking? There are records of many other types artisans but not glassmaking. It has been hypothesized that it is because the nobles did not own the glass furnaces so they did not leave a record of it in their pyramids or other adorned buildings. It is interesting how they made vessels because glass blowing did not reach Egypt until the 2nd century.The Egyptians put clay forms that were covered with cloth and dipped into molten glass. The glass was then spun to make it even. Then later they scraped out the cavity.(http://www.touregypt.net/historicalessays/lifeinegypt12.htm) An interesting article on the importance of Egyptian glass making is http://news.nationalgeographic.com/news/2005/06/0616_050616_egyptglass.html

Glass making in Mesopotamia (document based)

A good way of looking at history is by looking at the written records of the people of the time Cuneiform has been found that describes glassmaking in Mesopotamia:

One group of clay tablets detailing glassmaking is from the library of King Assurbanipal (668-627 B.C.) and is currently housed in the British Museum. Part of the translation of the tablets (from Glass and Glassmaking in Ancient Mesopotamia by Leo Oppenheim) is below.
“When you set up the foundation of kiln to make glass, you first search in a favorable month for a propitious day, and only then you set up the foundation of the kiln. As soon as you have completely finished in the building of the kiln, and you go and place Kubu-images there, no outsider or stranger should enter the building thereafter; an unclean person must not even pass in front of the images. You regularly perform libation offerings before the Kubu-images. On the day when you plan to place the glass in the kiln, you make a sheep sacrifice before the Kubu-images, you place juniper incense on the censer, you pour out a libation of honey and liquid butter, and then only, you make a fire in the hearth of the kiln and place the glass in the kiln…
If you want to produce zagindurû-colored [greenish type of lapis lazuli] glass, you finely grind, separately, ten minas [about one pound] of immanakku-stone [sand], fifteen minas of naga-plant ashes, and 1 2/3 minas of 'white plant.' You mix these together. You put them into a cold kiln which has four fire openings, and arrange the mixture between the four openings… You keep a good and smokeless fire burning until the glass glows golden yellow. You pour it on a kiln-fired brick and this is called zukû-glass.
You place ten minas of “slow” copper-compound in a clean dabtu-pan. You put it into a hot chamber kiln… You crush and grind finely ten minas of zukû -glass. You open the door of the kiln and throw the ground glass upon the copper compound…When the glass assumes the color of ripe grapes, you keep it boiling for a time…After it has become yellow [hot], you observe some drops forming at the tip of the rake. If the glass is homogeneous, you pour it inside the kiln in a new dabtu-pan, and out of the cooled-off kiln emerges zagindurû-colored glass.” (http://www.cmog.org/article/origins-glassmaking)


What does this document tell about society in Mesopotamia?
Was the process of glassmaking just a technical process? Why do you think this is?
What does the ability to make glass tell you about Mesopotamian society?

Recycling

Glass is highly recyclable. Ninety percent of recycled glass is used to produce more glass containers. The rest can be used on tile fiberglass, beads etc. Being ecofriendly is a big concern these days and glass is highly recyclable.  According to the recycling coalition of Utah, one ton of recycled glass saves:

• 42 kWh of electricity.
• 5 gallons of oil.
• 714.3 Btu’s of energy.
• 2 cubic yards of landfill space.
• 7.5 pounds of air pollutants from being released.
• 1,330 pounds of sand.
• 433 pounds of soda ash.
• 433 pounds of limestone.
• 151 pounds of feldspar.

 

Cullet- Recycled Glass

What  is more environmentally friendly glass or plastic?

Glass can be recycled over and over forever and it keeps its color strength purity, clearness and quality. It is 100% recyclable. Plastic on the other hand, because of the change in the chemical structure is made into other products unlike glass. Plastic loses its integrity, causing downcycling. That is why water bottles do not become water bottles again with plastic, but can with glass. On the other hand recycled glass takes 66% of energy used originally to make same product. Plastic takes only 10% of original cost to make a different lower quality item. It is obviously good to recycle. Which do you think is the better to use: glass or plastic?

 

Jamestown Glass

I think it is interesting that one of the first business ventures was glassmaking and not for the new world but to send back to England. I grew up in Virginia and did not learn this, but it is true. The glassmaking venture was not very successful.  It makes a lot of sense because unlike in New England, Jamestown was settled to make a profit. England was burning up their forests and to make glass you need to fuel the furnace. It made sense to bring the glass industry to a land of virgin forests. There were problems though. Glassmaking was a skilled job English glassmakers did not want to go to the wilderness. Why should they? So the company had to bring glassmakers from Germany and Poland. Later they brought Italian glassmakers. Sickness, dissent, death and Native American attacks were also problems. A final problem is the fact that the sand was not good for glassmaking, they even thought about bringing sand to Jamestown. These factors led to the end of glassmaking in Jamestown. Though not successful Glassmaking was one of our first industries. You can visit Jamestown to see glass house ruins. Jamestowns website http://www.nps.gov/jame/index.htm

June 6th Blenko Glass Visit

 On June 6, 2013 we went to Blenko Glass. We learned a lot about glass and were able to make a couple of water bottles ( these have been made continuously since 1938) and a candy dish with some help fom the glass workers. I took pictures and video of making the water bottle that I am making a movie with. In this blog I want to talk about things I learned. Blenko uses white silica sand not the sand from beaches. It is mined in Ohio or Michigan. They have not had much success finding the right sand in West Virginia. Glass that comes from this sand is not clear but

more like the shade of coke bottles. A powder
blue oxide is added to make it clear. In fact all

t

the colors are made with metal oxides except one. Topaz or amber is made using sugar and sulfur to give it that yellow color. Red glass is a hard to make a good color.  Glass like seen in the pictures is recycled and reused. The sand is heated for 20-40 hours to melt sand.  Glass's melting point is 2300 degrees.  It kind of looks like taffy and when on walls looks like ice or stalagmites.
       They used two different type molds. Metal molds that do not shine as much. The other mold is made out of wild cherry wood that creates a shine
 in the glass it makes. The wood molds are kept in water to make them last longer. The vats that hold them smell horrible, but the molds make pretty glass. Wood tools are also made out of the wild cherry wood.
       Blenko works in teams of 16. It is faster
 than each person doing all the steps. It takes
 7-10 years to become a glass blower and finisher. The system works well and they produce beautiful glass.