Glassblowing Basics: Equipment, Part 1
Hello! Welcome to my new blog series! I hope you find this to be interesting and gives you better appreciation for hand blown glass. I'm hoping this series will act as a source of reference for you. This is my world ~ I am excited to share!
The furnace is the heart of a glassblowing studio, and stays on 24/7 at 2100 degrees Fahrenheit. I work out of a non-profit glass facility called Public Glass in San Francisco. Public Glass has a 600 pound capacity, electric furnace, which you can see here, which periodically gets "charged" with new or recycled clear glass based on use. Molten glass is held inside a crucible that gets swapped out once a year for maintenance, as a failure in the crucible is a dramatically detrimental occurrence that I've only witnessed online. Essentially, molten glass will eat through the walls of the furnace and will spill out the bottom, destroying anything in its way.
Here, you can see my friend, Minami gathering glass out of the furnace. Gathering is the process of spooling molten glass on the end of your pipe or punty. At 2100 degrees, glass is like the consistency of honey. It's weird to think that all hand blown glass is made out of a formless glob on the end of a pipe, right? It takes years of practice to control your gathering technique!
These are pipes and punty rods. Pipes have a hole running through the body of the rod, and is used for creating blown work. Work made on pipes will typically be transferred onto a punty rod in order to finish the glass from the opening. Punties do not have a hole running through its body. Both pipes and punties come in all sizes, each to satisfy a specific need, and can come in a variety of diameters, materials, with or without grip, counterweighted, etc. I had mine custom made to be 4 inches shorter than the industry standard (not shown), to fit my needs.
You will typically see at least one bucket next to any glass furnace. The strip bucket is where you off-load some glass after gathering, since it's difficult to measure how much is gathered until you're out of the furnace. The hot end of the pipes and punties can be quenched in the water bucket in order to clean or cool it down before gathering. The clear glass from the strip bucket will eventually get recycled back into the furnace.
This is the pipe warmer heating the tips of pipes and punties because glass doesn't like to stick to cold rods.
Minami is cooling her punty rod with the pipe cooler because the rod gets hot after gathering from the furnace. The rod is cooled in a trough of water that gets recirculated through a bin of water. Public Glass' pipe cooler is made custom out of an old beer keg.
The gloryhole is the reheating chamber that we use to extend the workability of glass after gathering from the furnace. The gloryhole is heated with forced air and natural gas, and is around 2000 degrees Fahrenheit. Unlike the furnace, the gloryhole can be turned off when not in use, with the ability to adjust its heat. As a glassblower, you must constantly move the glass from the gloryhole to the bench, where the glass gets manipulated in the desired shape. You only have a short window of opportunity to reshape glass before it loses its workability due to becoming too cold and rigid. Depending on what is being made, the glass' workability outside of the gloryhole can be a few seconds to a few minutes. The yoke sits on a set of metal rails, allowing the glassblower to easily rest the pipe or punty while in the hole, and makes for easy maneuverability in and out. The heat shield is very helpful in protecting the glass maker from the gloryhole heat.
There are many different types of furnaces, gloryholes, etc.. Every glassblowing studio looks slightly different. This is just showcasing the equipment that's currently available to me and one day I hope to have my own. By the way, Public Glass has lots of options for classes if you're interested in trying out glassblowing. Not a paid promo... just letting you know in case you're interested and in the area.
Thanks for getting this far! If you have any feedback or questions, leave it in the comments :) Stay tuned for next week's Equipment, Part 2!