How to make a Glass Drop Ring.
Drop Rings can be used to make a wide range of objects such as glass vases, bowls, and even sinks. The most important thing to remember is to be patient and attentive when observing the glass during the slumping portion of the firing. This will ensure that you obtain good results.
All drop ring molds have small hole in the center and are best used suspended on kiln posts or stilts before firing your glass.
- If the drop ring is made of vitreous clay or a similar substance, apply kiln wash to the top side of the ring, including the edges, and let dry completely.
If you are using a drop ring made of stainless steel you will need to apply a Boron Nitrate Spray as a release primer. It is an excellent release for slumping temperatures but is not recommended for full fusing temperatures.
- Cut your circle or oval of glass slightly smaller than outside circumference of the drop ring. If the circle is cut larger than the ring you may trap the ring and crack the glass as it cools. This glass can be fused in a separate firing before slumping.
- The glass needs to be at least 1/4" (6mm) thick (two layers of standard glass). In general the glass should be 1/4" (6mm) thick for the first four inches you want to the glass to drop/slump, then an additional 1/8" (3mm) thick for each two inches after that. If you are making a large item such as a sink the glass will need to be at least a half inch (and probably a full inch) thick.
- Because of the potentially lengthy glass soaking period associated with using the drop ring, it’s usually a good idea to apply a devitrification spray to the glass surface to keep the glass shiny. Devitrification spray acts as an over glaze and a natural fluxing agent producing a durable, glossy shine on the surface of your fired glass.
Make sure the spray has dried completely before firing the glass. Also, the larger the drop ring or longer the soak the more critical the spray is to maintain the shine of the glass surface.
- One major factor in the use of a drop ring is the determination of how far you should suspend it above the kiln shelf. A distance of a few inches will yield a shallow bowl, while greater distances allow for more dramatic drops like a vase. Once you know your length, this will tell you where to position your bottom shelf and the location of the drop in your kiln.
NOTE: Make sure you positioned the glass in the kiln so that you can see the bottom of your shelf in front of your peep hole. This will allow you to observe without opening the kiln and time exactly when to stop the firing process.
- Place a level on top of the stack of glass, mold and shelf posts before you fire and adjust until level. You want to insure the glass is centered evenly and that it is level in multiple directions. Adjusting the drop ring or kiln posts or firebricks which are propping up the ring to the desired height often will be enough to make things level. You might have to move the kiln in order to achieve a level reading. If you slump your glass on an uneven mold, the glass will not drop evenly or the glass will not be of even thickness on all sides. Most importantly make sure the stilts do not block the hole in the center of the ring and that you can view the project through the peephole of your kiln.
- Determining how far you should suspend the drop ring above the kiln shelf relies on how thick your glass starts out. In general the thicker the glass base the further the distance you can stretch the glass. 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. The key is to control the drop of the glass slowly.
- The initial heating of the glass is similar to any other firing schedule. You should fire to approximately 1300 degrees Fahrenheit, then soak and observe the piece by looking thru the peep hole in the kiln side. Make sure you are wearing appropriate safety glasses.
- Initially, the glass will poke a small bulge through the hole in the ring. As the glass continues to soak the glass will droop through the ring. It is critical to keep monitoring the glass as it drops and hits the kiln shelf.
- Once the glass has dropped far enough to touch the kiln shelf, you will need to continue to monitor the glass until it takes on the desired shape. Be careful to not to over fire or the base of the glass will be too heavy and the sides too thin and will crack or puncture after annealing. Distortion usually only occurs if the kiln is not level.
- When you are happy with the appearance of the glass, flash vent to stop the slumping and then anneal and cool as normal. It is recommended to allow the kiln to reach room temperature before opening or removing your glass piece. Never open the kiln once it goes below 1,000 degrees.