Glass Fusing

I just inherited an older Duncan kiln that uses cones I want to fuse answer slump glass in this as it is larger than my glass kiln. What cones do I use and how long does it need to fire there are 2 dials on kiln having low,med, and high

I just inherited an older Duncan kiln that uses cones I want to fuse answer slump glass in this as it is larger than my glass kiln. What cones do I use and how long does it need to fire there are 2 dials on kiln having low,med, and high

@ When slumping glass that has already been fired to create a 1/2" thick slab of 12" diameter, it will be very important to slow the ramp rate and include soak time on the ramp up to avoid thermal shock. The following is in degrees Fahrenheit. Try a schedule of ramp rate 150/hour to 1000 degrees, soak 30 minutes. 150/hour to process temperature (about 1275), soak 15 minutes. 999/hour to 900 degrees, soak 2-3 hours. 300/hour to 700 degrees then shut down and allow to cool fully to room temperature before removing the project from the kiln.

@nancyknuckey There are several reasons that air can be trapped and form a bubble in the center of your project. The most common is that the glass is being heated unevenly and the edges are becoming soft and sealing shut before the center softens. To help alleviate this, you can reduce the rate your kiln is heating at and add a "bubble squeeze" segment to your firing schedule. Another tactic some artist find useful is to position little chips of clear fusible glass (compatible with the project) at intervals around the outside edge to act like tent poles, creating a tiny gap on either side for air to escape during firing.

I am getting trapped air in the middle of the saucer/coaster mold. I am using 2 layered fully fused glass. Should I drill a hole in the middle?

@ There are a few common reasons that the glass may not have slumped as desired. The first factor is that although kiln controllers often include pre-set firing programs based on averages, each kiln can fire a little differently. The size of the firing chamber, the material the kiln is constructed from, and the calibration of the controller can all be factors. You may want to adjust the firing schedule to have a longer hold time at the top process temperature to allow the glass time to slump, or you may need to increase the top process temperature slightly.Another factor can be the shape of the mold and size and thickness of glass used. For some mold shapes it is ideal to slump glass that was initially fused in a dam mold, allowing you to create a glass piece that is thicker than the 1/4" average achieved by layering 2 pieces of glass. You may want to experiment and try using this slumping mold with 3 layers of glass to see if the extra material and weight help it to reach the full depth and shape of the form.Additionally, make sure the vent holes in the mold are not clogged with mold release. These tiny holes allow the air to escape so the glass can slump to fit the contour of the mold. Trapped air may prevent the glass from dropping, or can even cause bubbles to appear in your project.

@ The process of fusing relies on heating the glass to a semi-liquid state. Setting a lower process temperature to achieve just a tack fuse will allow you to maintain a fairly crisp square shape, however, if a contour fuse or full fuse is desired, the glass will be liquid enough that the corners will round and the glass will either pull-in or flow outward to achieve a depth (or thickness) of approximately 1/4". If you desire a full-fused look and a square shape your options are to use a mold or dams to contain glass to a square shape, or to coldwork the fused project.

@gatormichals you do need to make sure to remove ALL of the Primo Primer. You might try a dry scouring pad or light sand paper to make sure that all of the primer is removed. Nylon panty hose and paper grocery bag can also do the job effectively. We offer a new product that is replacing MR-97 - it's called ZYP - it's in stock now.

Please I need a fusing experts advise, I have a slumping mold I've coated with 4 coats of Primo primer kiln wash but I've decided I'd rather use MR-97 on the mold instead; I know I can remove the kiln wash by with water and a brush, I believe I have removed most of the kiln wash the mold has a slight purple color my question is, Do I need to make sure all of the kiln wash is removed before I can spray the mold with MR-97? If there is still a slight purple color that would indicate there is still some kiln wash residual correct? Is there any thing else I need to do before I can use the MR-97?

HI Jennifer, I am going to increase the time of the middle 40 minutes & leave everything else the same. IF this doesn't work I will give Delphi a call, wish me luck !