Fire Polishing Fused Glass
Fire polishing fused glass is basically "glossing up" any dull surfaces.
These might be the result of glass that has had the edges ground, sand blasted or etched surfaces, etc.
It is usually done at around 1325 degrees Fahrenheit with a hold of some sort.
For soft edges, keep the temperature the same with a longer hold at the top temperature.
Fire polishing is done at a lower temperature than fusing.
Depending on the thickness of the piece, how much you want the edge polished, and of course the kiln will all determine how you fire polish the piece.
Prepare your piece.
If you need to grind the edges first, making sure they are nice and even.
Whenever employing a grinder on fused pieces, after grating the borders, place the finished parts in a container of water to preserve moisture on the edges.
This process will aid in the cleaning of these pieces.
If the grit from the grinding action dries out, it will be harder to get rid of.
Scour the drudged edges with a scrub brush, nail brush, or toothbrush and some soap and water.
After drying the piece, put the glass back in the kiln on a clean kiln washed shelf or fiber paper for fire polishing.
You must fire the piece up slowly, because you are working with a thicker piece of glass.
You will want to attempt this procedure on an item while it is flat, and before you try slumping it into or over a mold.
The typical temperatures are between 1300 and 1400 for about five to twenty minutes.
Spectrum usually polishes at about 1300 and Bullseye at about 1325.
Temperatures that are high enough to polish are also high enough to distort the edges of the glass, so stay at the polish temperature for only a short time.
Remember, you will want to polish an item while it is flat, before you try slumping the glass into or over a mold.
A suggested schedule would be:400 degrees per hour to 1000 and hold for 20 minutesAs fast as possible ramp up to 1300 and hold for 5 minutesAs fast as possible ramp down to 950 degrees and hold for 60 minutesThen down to 400 degrees per hour to 100 and turn the kiln off.
As you can see by this schedule, there are times to go fast and times to go slow.
You will get best results by fire polishing fused glass before you slump the item into a mold.
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