10 February 2018

For the LOVE of Vitrigraph

Did you know you can make your own stringer for use in kiln-glass work?

Vitrigraph is a special hot glass technique that involves pulling hot glass through a hole in the floor of the kiln. These glass stringers are fine strings of glass that can be used to create your own unique curved forms you can’t find elsewhere.

Bullseye Glass TechNotes 2 describes the vitrigraph equipment and processes developed at Bullseye in the early 1990s by Narcissus Quagliata and Rudi Gritsch, in the process creating a whole new vocabulary for fused glass.

Here are some quick vitrigraph tips:

Glass Feedstock 
Any scrap pieces of compatible sheet glass or coarse frit can be melted down to make lines or “stringers.” Avoid glass granules smaller than coarse frit, as they produce a seedier stringer due to the greater amount of air trapped between the smaller particles.

Loading The Glass
Load the glass into the pot outside the kiln, while it is at room temperature, and then place the loaded pot into the kiln so that it is supported. When working with frit or extremely small pieces of scrap sheet glass, place a small square compatible sheet glass the same color as the feedstock over the hole to prevent the glass from falling out. Then fill the pot with the feedstock.

As we just stated, loading the amount of glass needed for a run of stringer while the pot is cold, and then cooling between runs is the best option. However, if time forces you to do continuous melts, or if it becomes necessary to add more glass to the pot during the melt, here are a few things you need to keep in mind... Always, turn the power off before adding more glass. Use extreme care when filling the pot as glass scraps or frit which miss the pot and land on the electrical elements can damage them. Finally, glass scraps or frit that melt against the refractory brick will corrode it.

Vitrigraph Pot 
Avoid pots with hairline (or larger) cracks, as these will widen as they reach molten glass temperatures. In our experience, unglazed Italian terra cotta pots are the most durable. Avoid re-firing a used pot. The risk of cracking is far greater than the minimal expense of a new pot. As mentioned above, watch out for cracks. They widen and eventually break on firing.

If you want to see in a vitrigraph kiln in action, Bullseye Glass has a great video in their Kiln-Glass Education Online. In the lesson, you can see how they transform a Paragon Caldera kiln into a vitrigraph kiln and how to safely hand-pull stringers.

Most importantly, have fun and enjoy the process! It's a good one!