Glassblowing 101

Glassblowing is a unique art form that requires not only a creative mind, but physical strength and dexterity. It became very popular in the 1960s when the Studio Glass Movement lead to glass artists working in their own studios, similar to ours. Glassblowing is seen as a mysterious and magical process and we frequently get asked questions about it. We put together this blog post to give you an idea of the basic studio setup, tools and the process of glassblowing. We hope it’ll inspire you to try glassblowing yourself!
Furnace: Our furnace consists of a tank that can hold about 800lbs of clear glass. It runs 24/7/365 and is kept between 2000 and 2400 degrees Fahrenheit. The furnace is made of high temp ceramic castable and it takes about 6 days to reach the correct temperature, so if it ever goes out, we’re out of commission for a few weeks! We also have a smaller 200lb furnace, which is used for special orders that require colored glass. Glass takes a while to melt, so furnaces allow us to keep a great quantity ready for use at all times.
Re-heating Chamber: We have two reheating chambers and one is the largest in Michigan! Reheating chambers are kept at about 2100 degrees Fahrenheit and are turned on about an hour before they need to be used. Our smaller chamber is our workhorse and we only use the large one for special projects as it uses a lot of resources and requires more assistants with a high level of skill. Reheating chambers are necessary for continually reheating the glass to keep it at a working temperature so it can be manipulated.

Soda-lime Glass: We get our soda-lime glass from a company called Spruce Pine, that is located in North Carolina. The glass arrives in a raw material, called batch, and it has to be put into the furnace to melt. The process of filling the furnace and melting batch is called a charge. Because we have such a large furnace, this is a long process that takes about 12 hours to compete to melt about 1,000lbs of batch! While the batch melts in the furnace, it takes on an acidic quality and eats away at the interior of the furnace, so the furnace has to be rebuilt periodically.

Annealing Oven:
Annealing is the gradual cooling of the glass down to room temperature. Our annealing furnaces run on a computer program and the length of time for pieces the size we tend to make is about 16 hours. Larger pieces take a longer period of time in the annealer.
There are different types of annealing ovens. Ours is an upright with four shelves. An alternative is a top-loading annealer, which opens like a cooler and pieces are placed inside.
Annealing is necessary because if glass is not gradually cooled down, it can go into shock, resulting in breakage.
Tools are extremely important for a glassblower. While working at the bench, they will almost always have a tool in hand to work the glass. The image below shows just some of the tools that are kept on the bench. We’ll take a look at each of them and how they are used.

Tweezers: Tweezers used for glassblowing are just like other tweezers, but larger. The pointed tips are used to stretch and pull hot glass.

Jacks: Jacks look similar to tweezers but larger and they have a springy handle. This allows the glassworker to control the space between the blades to manipulate and change the shape of the glass. Jacks can be used in a variety of ways. The blades can be used to shape a vessel as it’s being inflated. If the blades are held close, they can help to create a constriction to separate the glass from the blowpipe. They can also be used to create an opening of a vessel. If they are flipped around, the straps on the jacks can also be used for shaping glass. The video below shows how the jacks are used to push the glass up the pipe.