Behind Carol Milne’s Secret ‘Knitted Glass’ Techniques

In Session Three at The Studio, we find a special process in the work room. Carol Milne teaches the technique of creating glass pieces that appear to have been knitted! This week-long class takes an intensive look at the steps behind creating her amazing works. From knitting wax sprues, to forming plaster molds, to creating the final pieces, this unique process results in some fantastic works.

Nadina Geary forms a wax positive from wax sprues, which are long wax rods that come in different shapes and thicknesses

Nadina Geary forms a wax positive from wax sprues,
which are long wax rods that come in different shapes
and thicknesses

Step one: Student and glass artist Nadina Geary forms a wax positive from the sprues. The idea is to form the shape of the final product in wax. These wax sprues will become the negative in the plaster mold. The base of the piece is currently a cup covered in wax and will eventually hold the glass as it is heated to its melting point. This cup is called a reservoir. The molten glass will eventually enter from this reservoir.

Looking into the reservoir at the base of the plaster mold after steaming the wax out, we can see how glass enters the form.

Looking into the reservoir at the base of the plaster mold after
steaming the wax out, we can see how glass enters the form.

In the above image, you can see the holes in the bottom of the reservoir where the glass will pass through to get to the negative where the sculpture will be.

Two students work together to get plaster completely covering the wax positive.

Two students work together to get plaster to completely
cover the wax positive.

Step two: Here we have two students coating a wax sculpture in layers of plaster to form a mold into which the glass will be melted in the next step. No less than five layers of plaster are used in this process, in addition to a layer of fiberglass mesh which adds strength to the mold.

The plaster cast sits under a plastic bag while the wax is steamed out. Steam comes from underneath the mesh table and rises up into the bag.

The plaster cast sits under a plastic bag while the wax is
steamed out. Steam comes from underneath the mesh table
and rises up into the bag.

Step three: It’s time for the plaster molds and wax to get a steaming treatment. Sounds kind of nice, doesn’t it? The steaming process allows the wax to heat up and melt out of the plaster form, creating negative space. Once the wax has been steamed out, the final part of this step is to wash out the negative space with boiling water, removing any remaining wax.

The glass chunks are wrapped into paper and hammered into pieces as to allow for the proper weight of glass to be measured into the reservoir.

The glass chunks are wrapped into paper and hammered
into pieces as to allow for the proper weight of glass to be
measured into the reservoir.

Step four: This is where the glass is weighed out to match the amount of negative space that is in the plaster mold. Shown above are the pieces of glass that have been smashed to create the correct amount.

The plaster casts rest in the kiln before students remove them to start unearthing their glass pieces.

The plaster casts rest in the kiln before students remove them
to start unearthing their glass pieces.

Step five: Now that we have a plaster mold that possesses a negative space, it is time to put the piece in the kiln. The kiln heats up slowly allowing moisture to escape from the mold. Once the kiln gets up to peak temperature (1,530 degrees Fahrenheit) it stays there for many hours and gives the glass time to melt into a consistency described by some of the students as akin to honey. The glass then slowly makes its way from the reservoir to the hollow space in the mold, forming the final sculptural piece. The annealing process that follows is where the temperature is slowly reduced to remove stress in the glass, keeping it from fracturing.

Students are seen removing the plaster cast to get a look at their near completed works.

Students remove the plaster casts to get
a look at their near-completed works.

Step six: It’s time to open the mold. Students use fine tools to remove pieces of plaster from the glass it surrounds. It is important to remain cautious as the plaster is removed and to not ding the glass sculpture with the plaster removal tools. This process is “like archaeology,” Carol says.  “Every time you open a mold it’s like a holiday! I’m happy to see what happens and be surprised.” Student, Su McManus, describes the excitement and anxiety of opening the mold by saying, “I pray that if it’s not in one piece, that I like the pieces it is in.”

The Studio of The Corning Museum of Glass offers classes in a variety of techniques taught by top international glassmaking artists and instructors. Interested in learning more? Spaces are still available for summer intensive classes. Find out more at www.cmog.org/classes.

2 comments » Write a comment

  1. i live in uk and cannot find anywhere that sells wax rods apart from thinnish wax wire which keeps breaking due to heat from hands any ideas or names of suppliers even if in america please. many thanks

    • Hi Carolyn – One of our glassmakers suggested googling “sprue wax.” She said sh’e pretty sure that even Amazon sells it. Good luck!

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