In the spring of 2009 Team Northstar took first place at the Glass Craft Expo International Flame Off with their incredible Skull Chandelier. The chandelier was inspired by a chandelier located in The Sedlec Ossuary, a small Roman Catholic chapel, located beneath the Cemetery Church of All Saints in Sedlec, a suburb of Kutná Hora in the Czech Republic. The Ossuary contains approximately 40,000-70,000 human skeletons which have been artistically arranged to form decorations and furnishings for the chapel.
Due to the shear size of the piece the team needed something more then the standard flame working equipment. The Skutt Crucible Furnace, GM818-3 CR, allowed the team members to melt and gather large amounts of glass needed to build certain components of this piece, primarily the skulls. Here is the process:
Northstar Colored Cullet
Scraper (shovel like tool 4 inches wide and 4inchs long shaped with a curve to match the crucible walls)
Kevlar gloves (this will protect your hands from massive heat)
Large pair of shears (to cut the tails of glass that come from a gather).
The Skutt Crucible Kiln - GM818-3
The chamber size of the furnace is 17.5” wide by 18” deep. You will want size your crucible OD to allow at least 2 inches of clearance from the elements. The height of the crucible should place it level with the bottom of the lid. This will make gathering easier and limit the amount of glass that can drip in the chamber. If your crucible is too short you can set it on fire brick to adjust the height. Make sure it is stable. The last thing you want to do is have that crucible topple over in the furnace. If it does, do not touch the glass. Molten glass conducts electricity and can shock you. The crucible used in this project was an Engineered Ceramics crucible, 12.5” high and 9” in diameter. It holds about 30 lbs of glass. We posted it up on K26 fire brick.
You want to heat the furnace at a fairly slow rate, 200 ˚F/hr, to prevent thermally shocking your crucible. Heat the furnace to 2300˚F. This is the temperature at which you melt the colored cullet. Skutt does not recommend using batch because the out-gassing is much more corrosive and will severely shorten the life of your elements and brick. Once the furnace reaches temperature you can charge about 4lbs per hour. Be careful not to pile it too high and risk having the glass stick to the lid.
Segment Rate Temp Hold
1 200 ˚F/hr 2300 ˚F 10 Hours (When glass is melted use the “Skip Step Feature to advance to the next segment)
2 200 ˚F/hr 2350 ˚F 99.99 Hours (When you are finished use the “Skip Step Feature to advance to the cooling segment)
3 200 ˚F/hr 200 ˚F 0.00 Hours (Furnace will shutoff when it reaches 200 ˚F
Borosilicate glass is very similar to melting metal. When melting metal you have a slag layer that needs to be scraped off before you have good clean metal and the same goes for borosilicate glass. After you scrape off the slag layer of glass (1/2 deep) you will be ready to do what ever your mind can handle. If you let the glass sit for more than 3 hours the slag layer comes back and needs to be scraped again.
We recommend you use clear glass tubing and rod to start your gathers. This will allow you to start with a large scale mass without multiple gathers. We also recommend you use small or large metal punties and blowpipes. This will allow you to have more stability with the hot molten glass. When you dip in the crucible with your clear or metal rod or blowpipe, you will need to cut the glass stringer that is trailing the gather, we recommended a pair of long diamond shears or large loppers for tree pruning.
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