Because I have worked with glass for 20 years, I have delved into many of its techniques. After all, the myriad of techniques is what first attracted me to glass. It is the only medium that cam be worked cold, warm and hot. But, because of the diversity of techniques, my studio looks more like a torture chamber than a place of creating art. I have glass of every size, shape, color, and COE. Remembering what each glass has the potential to achieve has become very difficult. This is especially true for those wonderful, colorful, overachieving borosilicates. However, through a simple technique learned from Brian Kerkvliet, I feel I have made progress solving this problem.
Although Glass Alchemy has made it very easy to determine what their color will do through their marvelous numbering system, there still existed a physical need for me to learn how to make the color rod do what it is supposed to do in the flame. Merely sticking a rod into a neutral flame and making a ball just didn’t do it for me. Because some of my work is of the blown variety I needed to know what happens to the color while and after it has been manipulated and taken to its extreme. I found the answer by coiling a rod on the end of a small diameter tube and blowing a ball. The following describes how to do this technique.
To examine a color, take a small diameter tube (about 12mm or 13mm) and cut it into 8-inch lengths; just long enough not to burn yourself from the flame and short enough to be able to throw the whole thing in the annealer.
Create a neutral flame on your torch and flame polish the blowing end to avoid cutting your lip. Make sure the blowing end is cool before you stick it into your mouth. I prefer to also reinforce the working end of the tune with an extra coil or two of clear glass so that the tube can take a little more heat and won’t melt and collapse while working.
Then take a rod of the color your want to test and start the coil on the reinforced end of your tube. Working in the neutral flame area, twist and turn the rod as you coil so as not to heat one side hotter than the other. The goal is to create a ball form, so work the coil outward and thin back in, sealing it off at the top. (You can make a nice working ball with only half a color rod.) Then starting back from the tip, slowly reheat the ball until the entire piece is red hot.
With the non-silver colors, you can marver and blow while working to get a nice even internal wall. With the more heavily saturated and silver colors, marvering and taking the piece in and out of the flame while heating may cause color distortion. The cadmium colors should be worked farther our in the flame as they tend to sublime (turn directly from a solid to a gas) in a neutral or hot reducing flame.
When the whole ball achieves a nice red a glow and becomes slightly floppy, gently blow out into a larger ball—this gives you a feel for the elasticity and density of the color. Keep the rod turning while blowing or your nice coiled ball could end up as a giant blob on the floor. With the more heavily saturated and silver colors, mentally divide the ball into sections and work each section in a different flame setting—or create different decorative effects.
Take notes on what happens and keep them in a well-organized notebook. A good notebook is worth its weight in color rods. Also, remember that you may not be able to tell what the color will do until it comes out of the annealer, so take notes on how long it has stayed in the annealer. If it goes to a striking range, note the length of time it stayed at that striking temperature. When the piece has been annealed and cooled, mark the color, manufacturer, and code number on the tube with a permanent marker. You can also mark the tubes with a reference number from your notebook. For a more secure marking make a label for your tube with a label maker—a tool I have found very useful in my studio. To keep handy for future reference, the balled tubes can be stored upright in a flowerpot.
This technique should help you determine what your colors can and can’t do before you create your masterpiece. It is also helpful in determining what colors to use and which colors look good together. Most borosilicate color doesn’t come out the same way it went in and can change with even the slightest adjustment in time, temperature, or manipulation. Better to be knowledgeable beforehand and avoid having to throw away a work in progress. Happy coloring!