How to Fuse Moretti Glass

Moretti glass is a soft glass. Historically, it's been manufactured on the Italian island of Murano. Moretti glass is also known as soda lime glass and Effetre glass. It comes in transparent and opaque colors. It's produced in rods of various diameters, sheets, frits and stingers. When fusing glass, it's important that their coefficient of expansion---or rate of expansion---are compatible.

Things You'll Need

• Ceramic brick kiln with pyrometer
• Kiln shelf
• Kiln stilts
• Kiln wash
• Water
• Brush
• Clear glass
• Paper towels
• Colored Moretti glass-frits, stringers, sheets

Instructions

1. Prepare the inside of the kiln and the kiln shelf. Mix kiln wash---a pre-mix powder consisting of kaolin clay and alumina hydrate---with water until it reaches the consistency of cream. Brush it on to the bottom of the kiln and the kiln shelf. Let it dry. Brush the next coat on at a 90-degree angle to the first coat. Let it dry. Repeat until five to six coats have been applied.

2. Heat the kiln to 500 degrees to evaporate the water in the kiln wash. Put a small 1-inch kiln stilt under the lid to keep it cracked to vent the moisture.

3. Take two pieces of 1/8-inch-thick clear glass, 4 by 4 inches. Clean them well, using paper towels, on all sides to eliminate any dirt, dust or finger prints. Make sure the glass is completely dry.

4. Set the kiln washed kiln shelf on a work table. Pick up one piece of glass by its edges and set it flat on the kiln shelf. Set the second piece of clear glass on top of the first.

5. Create a design or pattern by sprinkling colored glass frit---granular glass, colored glass stringers---strings of glass, or thin sheets of colored glass. Don't overlay the colored glass elements too much.

6. Set the shelf with the glass tile prepared for firing into the kiln. Fire the kiln to 1000 degrees Fahrenheit at 600 degrees per hour. Watch the temperature gauge on the kiln's pyrometer.

7. Fire to 1175 degrees Fahrenheit and hold the kiln temperature there for 30 minutes to give the glass time to relax and to minimize air bubbles in the glass

8. Fire from 1175 degrees to 1450 degrees Fahrenheit as fast as possible. At 1450, wait 10 minutes then remove the peep hole and look at the glass tile to see if it has fused. The edges of the glass should become rounded. Keep checking every two to three minutes. It shouldn't take anymore than 20 minutes for the glass to fuse at 1450 degree Fahrenheit.

9. Lift the lid of the kiln up once the glass has fused to flash cool it. Keep opening and closing the lid until the temperature drops to 1000 degrees. Rest the glass for 10 minutes by keeping the lid closed and the peep hole plug in the kiln. If the temperature rises back up some during this 10 minute hold, that's alright.

10. Drop the temperature of the kiln to 950 degrees Fahrenheit and hold it there for 30 minutes. This is the annealing stage. This insures the glass is heated evenly all the way through and won't be susceptible to cracking, crazing or shattering once it's cooled down to room temperature.

11. Turn the kiln off and let it cool down slowly for hours until its room temperature.

Tips & Warnings

• You can use honey as an adhesive to hole your colored glass pieces in place on the clear glass. It'll burn off in the kiln.

• Instead of laying the glass flat on the kiln shelf you can use slump molds which will give the glass a slight concave or convex shape. Molds must be painted with kiln wash too.

• Always wear tinted glasses when looking into a red hot kiln.

• Wear fire resistant gloves when flash-cooling the kiln by lifting the lid up and closing it down.

• Be careful when handling any kind of glass to avoid cuts or slivers.

References

• Art Glass 2: Fusing Glass