*Glassblowing can be extremely dangerous. Please do not attempt this activity without the aid of a trained professional*
*Information provided here is simply to engage your group prior to a class or meeting with a trained glassblowing artist*
*Extra links and resources have been added to plan a more in-depth look at the art, history, and science of glassblowing*
Mother Nature is the original glass worker. Glass is made by applying extreme heat to certain natural materials such as sand and rocks. Lightning strikes on the sand of beaches and deserts creates glass rods called fulgurites. Volcanic eruptions also create glass, when lava flows fuse sand and rocks into obsidian. Scientists have even found glass of extraterrestrial origin, most likely carried to Earth by meteorites or comets.
*Find a few pictures of each of these types of naturally formed glass. *
Glassblowing is a glass forming technique that involves inflating molten glass into a bubble with the aid of a blowpipe, or blow tube.
A person who blows glass is called a glassblower, glassmith, or gaffer.
A lampworker manipulates glass with the use of a torch on a smaller scale, such as in producing precision laboratory glassware.
Glassblowing involves three furnaces. The first is simply referred to as the furnace. The second is called the glory hole, and is used to reheat a piece in between steps of working with it. The final furnace is called the lehr or annealer, and is used to slowly cool the glass, over a period of a few hours to a few days, depending on the size of the pieces. This keeps the glass from cracking or shattering due to thermal stress.
The major tools used by a glassblower are the blowpipe (or blow tube), punty, bench, marver, blocks, jacks, paddles, tweezers, newspaper pads, and a variety of shears.
The tip of the blowpipe is first preheated then dipped in the molten glass in the furnace. The molten glass is gathered onto the end of the blowpipe.
This glass is then rolled on the marver, which was traditionally a flat slab of marble, but today is more commonly a fairly thick flat sheet of steel.
This process forms a cool skin on the exterior of the molten glass blob, and shapes it.
Then air is blown into the pipe, creating a bubble.
Next, the glassworker can gather more glass over that bubble to create a larger piece.
Once a piece has been blown to its final size, the bottom is finished. Then, the molten glass is attached to a rod called a punty for shaping and transferring the piece from the blowpipe to provide an opening for the top.
The bench is a glassblower's workstation
It has a place for the glassblower to sit, a place for the handheld tools, and two rails that the punty rides on while the blower works with the piece.
Blocks are ladle-like tools made from water-soaked fruitwood, and are used similarly to the marver to shape and cool a piece in the early steps of creation.
Pads of water-soaked newspaper (roughly 6 inches square, one-half to one inch thick), held in the bare hand, can also be used to shape the piece.
Jacks are tools shaped somewhat like large tweezers with two blades, which are used for forming shape later in the creation of a piece.
Paddles are flat pieces of wood or graphite used for creating flat spots such as a bottom.
Tweezers are used to pick out details or to pull on the glass.
There are two important types of shears, straight shears and diamond shears. Straight shears are essentially bulky scissors. Diamond shears have blades that form a diamond shape when partially open. These are used for cutting off bigger masses of glass.
*Review, discuss, and share pictures and or/videos of the tools in action*
Glass Artist Stephen Rolfe Powell’s website is a great resource for this.
www.powellglass.com Includes pictures and videos of his art as well as his tools and processes.
Eye protection is very important for two reasons.
First, glass can sometimes shatter when placed directly in the flame, and you must protect your eyes from flying glass fragments.
You must also protect your eyes from potentially damaging Ultraviolet and Infrared rays
*Discuss what ultraviolet and infrared rays are and how they can be damaging to your eyes*
Glassblowing, if done improperly can result in a number of serios injuries including, lung damage or irritation, burns, cuts, bruises, and muscle strains.
*While visiting with a professional glass smith have them explain what safety measures are in place in their shop or work area and why they are in place*
*Before your meeting with the glass smith try a couple of fun experiments to better understand the working process. *
Have group members dip a coffee/tea stirrer into a small cup of honey at room temperature. Tell them to try to keep the largest gob possible of honey on the tip of the stick as they pull it out of the cup. They are simulating how a glass blower works with gravity to keep a gob of molten glass on the end of the blowpipe. If you're in the mood to get messy have your group members try to blow into their coffee stirrer and make the honey into a bubble.
Experiment 2: Stained glass (ADULT SUPERVISION REQUIRED)
Jolly Ranchers hard candy
Nonstick cooking spray
1/4-inch satin ribbon eight inches long - same amount as pieces of glass
Cut a piece of parchment paper to cover the entire top of the cookie sheet.
Preheat oven to 350 degrees.
Spray the inside of the cookie cutters with nonstick cooking spray. Place the cookie cutters on top of the parchment paper covered cookie sheet.
Unwrap the Jolly Rancher candies in your choice of colors. The amount depends on the size of the cookie cutter. It will range from three to eight. Arrange the candies inside the cookie cutters to your liking.
Put the cookie sheet in the oven once it has preheated. Bake for six minutes.
Remove the cookie sheet from the oven, it will be hot so use hot pads. Let it cool. When the tray is semi-cool use a wooden skewer to put a hole in the top of each molded piece of glass. You will put ribbon through this hole in order to hang it.
Pop each molded piece of Jolly Rancher glass from the cookie cutter gently once completely cooled. Thread a piece of ribbon through the hole you made in each piece and tie it in a loop. You are now ready to hang your stained glass.
https://science.howstuffworks.com/question404.htm Discusses why glass is transparent
https://entertainment.howstuffworks.com/arts/artwork/glassblowing.htm A more in-depth scientific look at glassblowing
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