Thursday, August 2, 2007

Freeze and Fuse Glass

There seems to be a lot of interest in the freeze and fuse technique recently, so I have tried to explain a bit of the process of Freeze-n-Fuse below. If the technique intrigues you, I've got more pictures that help explain a bit better here.
"What is Freeze and Fuse?," you ask. Well, simply put, it is making ice cubes with glass powder and slowly heating the ice in a kiln, so that as the water evaporates, the glass pulls in on itself and melts together.
This is a "new" technique recently discovered (or recently re-discovered since Ancient times). Phil Teefy of Rainbow Glass in Sacramento offered a workshop in Napa in September 2006, where we made some molds out of RTV Silicone, and then made glass leaves using the freeze and fuse technique. First, we made a clay base to rest the leaf on. We rolled out a sheet of clay, moistened it with drops of water, and place our leaves on the clay (vein side up). Using a dental pick tool, we made the lip of the silicone mold (in relief) by digging a 1/4" outline around the outside edge of the leaf into the clay. We then drew a light outline 1/2" away from the ditch, and then sliced the clay in a general leaf shape another 1/2" away from the outline.
Next, we needed to make a dam to hold the silicone mold making mix. Again, we rolled out some clay, using 3/4" spacers on either side of the rolling pin to ensure a level and evenly rolled clay strip. We sliced strips of clay 1" wide, and made a dam by placing the clay strips along the light outline and edge of the clay base.

Now we're ready to mix and pour the RTV silicone. The silicone mixture is quite expensive, so we measured the volume of our dam (L*W*H) so that we didn't make an excessive amount of silicone. After mixing the two part RTV silicone, we poured it into the mold, holding the bucket about a foot above the dam, and letting it run into the mold in a very thin stream, to prevent bubbles from forming in the mold. After pouring the mixture into the mold dam, we vibrated the table to help any bubbles that may have gotten trapped to work their way to the surface.

After the mold has set according to instructions...

Now we're ready for the fun, artistic, creative process of Freeze-n-Fuse! Yea!!
A side note: There are many readily available, pre-made molds (I've sorted out some here, but artist Kimberly Crick of The Enchanted Gallery has some fabulously beautiful molds which I highly recommend!) that can be used, so that you need not make your own mold. However, if you learn to make your own molds, you are limited only by your imagination as to what you can make!

A word of caution - a proper dust mask should be worn to prevent the inhalation of glass!

Tools: mold, plastic cups, Oral B "Hummingbird," spoon or stir stick, water, glass powder (frit size 08), a proper dust mask should be worn to prevent the inhalation of glass!

So, we have our mold. I added a just a touch of dry, white powder (frit size - 08) to my mold, and rubbed it into the veins. This adds a little contrast and pulls out the detail in the finished leaf.

From this point on, any powder that we add needs to have a little moisture.

Start by measuring your powder into a plastic cup. You can mix colors with clear powder to create lighter shades. You may want to keep a record of the exact amounts of glass mixed (in grams) if you want to be able to replicate certain colors. It is easiest to mix several colors that you will be using in different cups before you are ready to pour them into the mold.

After you have measured out and mixed the glass powders in their separate plastic cups, you are ready to add a little water.

Add enough water so that you can mix the glass easily. The desired consistency of the paste that you are mixing will look liquid-y when you stop stirring, but will have a paste-like consistency while you are stirring it.

After adding water and stirring, lay the hummingbird horizontally across the top of the cup to vibrate the mixture and settle the glass to the bottom of the cup.

Pour off any excess liquid. Stir again and check the consistency. Add or subtract water until the paste-like yet watery consistency is reached.

After you have all your cups of paste ready, you can begin adding them to the mold, adding a little at a time and tapping with your finger to prevent bubbles or pockets of water from forming.

After the mold is filled, use the hummingbird again to vibrate the mold and settle all of the glass, shaking all excess water to the top of the mold. This water can be sopped up with the corner of a paper towel. Place the mold in the freezer for at least an hour, and not longer than overnight.

The water in the paste will start to dehydrate if the mold is placed in the freezer for too long, resulting in a finished piece that has "fallen apart".

After the piece has frozen, you can take it out and transfer it carefully to the kiln. The colder it is in your studio, the more time you will have to clean up your piece before firing it. Gently brush away any overhang or rough edges on your piece, after slipping it out of the mold. Place the piece in the kiln and fire.

Programmable firing schedule for Freeze and Fuse pieces in the kiln:

Segment 1:
190° per hour
190° temperature
1 hour hold

Segment 2:
500° per hour
1100° temperature
20 minute hold

Segment 3:
300° per hour (for small projects)

1275° temperature for a matte finish
1300° temperature for a semi-gloss finish
1325° temperature for a polished finished, but a little loss of detail

5 minute hold

This process is much easier to understand when you've got someone to watch, but with a little trial and error, you'll figure out the right consistency. (And it doesn't have to be too exact!)

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