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GLASS KNOWLEDGE

What Are Murrine?

Murrine, known as murrina in singular form, refer to patterns or images made in glass cane, which when cut reveals its pattern in the cross-sections. The art of murrine encompasses an extensive array of designs, ranging from simple circular or square motifs to intricate, highly detailed pictures, and even lifelike portraits of individuals. A renowned example includes the formation of flower or star-shaped motifs, which, when combined in significant quantities from various canes, are referred to as millefiori.

The origins of murrine production trace back over 4,000 years ago in the Middle East. This artistic tradition experienced a renaissance during the early 16th century, thanks to the skilled Venetian glassmakers located on the island of Murano.

Traditional murrine are created in a hot shop, and used for glass blowing. A molten lump of glass is gathered on the end of a metal rod, then rolled in colored glass, shaped in a mold and then the clear glass is layered around, this process is repeated numerous times. The resulting layers resemble exquisite flowers, resulting in stunningly beautiful creations.

However, vitrigraph murrine takes a different approach. It involves loading a vessel, which can be either a terracotta or stainless-steel pot with a hole at the bottom, with glass. This loaded pot is then placed in a small kiln, which also has a hole in the bottom. The kiln is elevated above head height, and heated to approximately 830 degrees Celsius. As the glass reaches a molten state, it flows and is carefully “pulled” into canes of glass through the hole at the pots and kilns bottom. The outcome depends on the arrangement of the glass within the vessel, leading to unique designs when the cane is sliced, revealing captivating cross-sections.

what are murrine

What Is Fused Glass?

Fused glass is a versatile and artistic glass-working method that entails heating glass to high temperatures, causing it to melt and form diverse shapes and designs. This technique is commonly executed in a specialized glass-firing kiln. In glass fusing, the glass goes into the kiln at room temperature, the kiln heats it to the required temperature to create the effect you want, it then cools the glass, including an anneal, and the glass is not removed until it is back at room temperature. This is different from a hot shop, where molten glass is manipulated. Fused glass empowers artisans and craftsmen to craft a diverse array of functional and ornamental items, spanning from exquisite jewellery and elegant dishes to decorative tiles and captivating sculptures.

what is fused glass

What Equipment Do You Need To Be A Fused Glass Artist?

First and foremost, you will need a kiln or access to a glass kiln, this could be as simple as a microwave kiln to a larger electrical one.

It is best to decide what fusible glass you want to work with, the 3 main options are Bullseye Glass – which has a COE of 90, Oceanside Glass – 96COE and Float – also known as window glass.

There is an endless list of equipment you can get for fusing glass, but to start with you will need:

  • Glass Cutter – to score a line
  • Glass Breakers and/or Grozing Pliers – to break the score
  • Safety Gear – glasses, gloves if you like, and a mask if you will work with glass powders
  • Adhesives – from simple Elmers glue to Bullseye Gell glue, I love gluing my pieces before I put them in the kiln
  • Glass molds – if you want to shape your glass

Then watch as many videos and read as many books as you can on the subject and give it a go. You will be amazed at what you can make.

fused glass tools

What Is A Firing Schedule?

In the realm of glass, a firing schedule plays a pivotal role. It is broken down into three segments.

  1. A temperature you want the glass to go to
  2. The speed you want to get to that temperature
  3. How long you want to stay at that temperature

Most firing schedules are then broken down into segments, each segment accomplishing a different stage of the firing, from initial heating and making sure all the glass is the same temperature, to a bubble squeeze to push any air out from between layers, quick heat through the devitrification range to top temperature, then annealing the glass, which takes 2-3 segments. I would advise purchasing and reading Bob Leatherbarrow’s book on firing schedules before you start.  Here is a link to where it can be purchased. Firing Schedules for Kiln formed Glass — Leatherbarrow Glass Studio.

Please be aware that firing schedules are very kiln-dependent, so a temperature and firing schedule that may work in one kiln may not work in another.

firing schedule

What Is The Difference Between Tack Fuse And Full Fuse?

The difference between a tack fuse and a full fuse lies in the temperature and duration of the firing process in glass art and glass fusing:

Tack Fuse

A tack fuse involves heating glass pieces to a lower temperature than a full fuse, typically around 1300 to 1400 degrees Fahrenheit (700 to 760 degrees Celsius).

The heating duration is relatively short, usually just long enough to bond the glass pieces together without fully melting and flattening them.

Tack fusing results in glass pieces that retain their individual shapes and textures while becoming securely attached.

Full Fuse

In a full fuse, glass is heated to a higher temperature, typically around 1475 to 1544 degrees Fahrenheit (800 to 840 degrees Celsius).

The glass is held at this elevated temperature for a longer period to allow it to fully melt and flow together, creating a single, flat, and smooth piece of glass.

Full fusing results in a homogeneous, uniform glass surface without distinct boundaries between individual pieces.

The choice between tack fusing and full fusing depends on the desired artistic effect and the specific project. Tack fusing is often used when artists want to maintain the texture and shape of individual glass pieces while creating a fused composition. Full fusing, on the other hand, is employed when a completely smooth and uniform glass surface is required, such as for creating glass plates, bowls, or other functional objects.

What Is The Difference Between 90COE And 96COE?

The key difference between 90 COE (Coefficient of Expansion) and 96 COE glass in glass art and glass fusing lies in their thermal properties.

However, when most people are referring to COE they are using a shorthand method to speak about its compatibility.

Compatible glass is glass that can be fused together. All Bullseye glass has been rigorously tested so that it can be fused together, we refer to it as 90 COE but the COE is not the important part, it is that it has been tested for compatibility.

90 COE glass and 96 COE glass can not be fused together as they expand and contract with temperature at different rates, which means that if you try and use them together you will end up with tension in the glass which will most likely break or even explode if used together.  This is why COE is important.

What Is Float Glass?

The Float glass name comes from how it is made; it is floated across a layer of molten tin during the manufacturing process. Float glass is the generic term we use for window glass. There are float glass fusing products that can be used on window glass and the glass you will find in lanterns you can purchase from many homeware stores, however due to the large range of COE’s these have we do not suggest you take them above a tack fuse.

what is float glass

Can You Mix 90COE, 96COE And Float In A Project?

Mixing glass with different COEs can lead to stress and cracking in the glass and destroying your project.

COE is a crucial factor in glass compatibility. It measures how much a glass expands and contracts with changes in temperature. Glass with different COE values expand and contract at different rates and as stated above projects using different COE will most likely break or even explode.

mixing different COE glass

What Do You Recommend For Cutting Murrine Cane?

We use mosaic glass wheel cutters to cut all our cane as this gives us the best results and are the easiest to use, we turn the wheels regularly to keep them sharp.  It has small, replaceable wheels that allow for precise cutting of individual murrine slices.

what do you recommend to cut murrine cane