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Can You Stand the Heat?

Flame Chemistry

The setting of a flame (a.k.a. flame chemistry) is a crucial aspect of a lampworker’s process. Different flames have varying effects on borosillicate glass.

Flame anatomy

Each zone or candle has its own characteristics such as color, sharpness, temperature, and length depending on the type of flame.

  • Inner Cone – upper tip is the hottest part of the flame
  • Intermediate Cone – not always present
  • Outer Envelope – coolest part of the flame
Example of Flame Zones
Example of Flame Zones

Flame Types

  • Diffusion – This is usually a starter flame. It is composed of mostly fuel and burns coolest of all flames. It is identified by its yellow-orange color and wispy appearance.

 

Diffusion Flame

  • Reducing – Once a little more oxygen (o2) is added, it becomes a reducing flame. It is produced when there is not enough o2 to cause the combustion of all the fuel. This flame has long yellow candles and an intermediate cone. It still has a bushy nature, but is more defined than a diffusion flame. A loud roar accompanies reduction.
  • Neutral – Mixing equal parts o2 and fuel will create a neutral flame. Being the hottest of the flames, you will notice a sharpening of the candles. The candles are also white with a bright blue outer envelope. Most of glass working is done here.
Neutral Flame
Neutral Flame
  • Oxidizing – This flame has more o2 than fuel. It is characterized with a hissing noise and even shorter cones. It can boil glass off. Therefore, it is important to keep the piece within the glass’ heat tolerance.
Oxidizing Flame
Oxidizing Flame

Flame chemistry can make all the difference between a cobalt rod being vibrant blue or dull grey. Learn more about the actual colors and setting effects here. When fuming precious metals, the flame used on gold would annihilate any silver that has not been encased. Basically, for every job, there is an appropriate flame, and Will has studied them to bring you beautiful, one-of-a-kind pieces.

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Now You See It

Silver Fumed Pendant
wormholep-01
Wormhole Pendant with silver fumed wormhole

Fuming is a subtle and delicate way of coloring glass with pure silver and/or gold. It has only been around for a few years but has steadily gained popularity since Bob Snodgrass made it a sought-after technique.

The process sounds simple:

  • Snip some 99.9% silver or 22k gold
  • Heat up a small diameter borosillicate rod and stick it to the snips creating a “punty”
  • Hold to the tip of a flame
  • Capture the metal vapor in the piece to be colored
  • Encase it with clear glass

However, this is a complicated process that takes years to perfect. Each metal requires its own unique flame setting and creates its own colors. The more fuming on a piece the more colored it will become.

Silver creates blues, whites, and maybe with enough fuming a yellow color. Gold requires a hotter flame and is known for purples, reds, pinks, or even burnt orange. If the fuming isn’t encased before the flame touches it again, it may evaporate.

GoldFumedPieceEach fumed piece will have its own individual characteristics. The nature of the colors will have both transmitting and reflective properties.

Transmitting colors are what you see as light passes through the piece. Reflective colors are simply the colors that are reflected back.

To see the true aspects of the fuming, place the piece in front of a white background to see the transmitting colors and a black background to see the reflecting colors.

Depending on the time in the flame, ratio of metals, and background, the entire color spectrum is possible.

Star Cluster with silver fumed stars
Star Cluster with silver fumed stars

Will uses fuming in some of his pendants. For example, the star clusters are created by shaving the silver and heating them just a little to create some fume without vaporizing all of it. This slight fuming gives the stars a “glow.”

This complicated process has been tried with other types of metals with no success. Harnessing smoke to get the desired effect requires significant skill and practice.

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Not All Glass is Created Equal

Misc. Glass Rods

Glass is glass right? Wrong!

There are several types made from a variety of formulas.

Soda Lime Glass (aka “soft glass”)

photo credit: open window via photopin (license)
photo credit: open window via photopin (license)
  • Standard glass is made up of a variety of chemicals melted together. It is usually used in drinking glasses, windows, etc.
  • When dropped or struck it shatters into sharp pieces that are difficult to clean safely. We’ve all spent time trying to get a tiny piece of glass out of a foot or hand.
  • The rate of thermal expansion is pretty high, which simply means that it expands rapidly when introduced to extreme heat. This causes it to shatter as if struck.

Tempered Glass (aka “safety glass”)

  • photo credit: crazed via photopin (license)
    photo credit: crazed via photopin (license)

    This type of glass is made up of the same stuff as regular glass and used for cookware, car windows, etc.

  • What makes it “tempered” is the process it undergoes after creation. It is placed in a tempering oven to harden. It must be pre-molded as it cannot be manipulated once tempered.
  • When it breaks, it crumbles into large or medium size chunks. Clean up is safer than regular glass, but still problematic as there are a large amount of pieces.

 

Now, to our main event.

Borosilicate Glass (aka “hard glass”)image1

  • You can find hard glass in places like scientific equipment, the space shuttle shielding, and here at SETX Glass.
  • Hard glass is made of all the same stuff as the other glasses. HOWEVER, the star of this mixture is the boron trioxide, which significantly reduces the thermal expansion rate.

So what?

  • It can be heated without expanding very much.
  • The added boron also makes the piece resistant to chemicals. This means that it will not look “dingy” over time.
  • What happens if you drop it? Well, it might not, but it will probably break (shocker I know). However, if it does break, it will crack into one or two pieces. Clean up is a breeze and no finding pieces with your foot later.

Will uses boro in ALL of his designs. It costs more and requires higher heat and effort to manipulate, but is so worth it. Each piece is heirloom quality, which means your great-grandchildren can wear your wormhole pendant with pride. It will be as pristine as the day you bought it.