USING THE DROP RING
The drop ring, an open mold usually made of vitreous clay or cut from fiberboard, can be used to make objects as diverse as bowls, vases, and kitchen sinks. The key to good results is patience and careful observation of the firing.
• Preparing to use the drop ring
If the drop ring is made of vitreous clay or similar substance, it should be kiln washed prior to use. Make certain the wash dries well.
To use the ring properly, you will need a circle of glass that’s slightly smaller than outside circumference of the ring. If the circle is cut larger than the ring, you may trap the ring and crack the glass as it cools.
The glass circle could be fused in a separate firing or you could simple cut and unadorned circle from a sheet of glass. If you are making a large item such as a sink the glass will need to be at least half an inch (and probably a full inch) thick.
Because of the potentially lengthy soaking period associated with using the drop ring, it’s usually a good idea to apply a devit spray to the glass.
One major factor in the use of the ring is the determination of how far you should suspend it above the kiln shelf. A distance of a few inches will yield a small bowl, while greater distances allow for more dramatic drops. The items made in this fashion are more likely to be vase-like.
Use kiln furniture or firebricks to prop the ring at the desired height. Make certain that the glass is clean and that any devit spray used has dried completely. Then center the glass on the ring, making certain that you can view the project through the peephole of the kiln.
The heating portion of the drop ring firing is similar to any other firing. You should fire to approximately 1300 degrees Fahrenheit, then soak and observe the piece.
Initially, a small bulge of glass will poke through the hole in the ring. As the glass continues to soak, more and more of the glass will droop through. Keep a careful eye on the glass as it droops.
It may take half an hour for the glass to droop far enough to touch the kiln shelf below. Once it touches, you will need to continue to monitor the glass until it takes on the desired shape. Be careful not to over fire or the base of the glass will distort unacceptably.
Once you are happy with the appearance of the piece, flash vent to stop the slumping and then anneal and cool as normal.