This tutorial will explain how I make custom ceramic texture molds to create fused glass art.
Items used in this tutorial:
1) Firing the clay, and glass:
Kiln: I use a Paragon Janus 23 multi-purpose kiln (capable of firing glass or ceramics with the flip of a switch!)
kiln shelf wash: Hotline Primo Primer Kiln Shelf Wash
plastic lidded container to mix and store shelf wash in
paintbrush to paint shelf wash onto shelves & molds (I use inexpensive Chinese brushes that are often used for glazing ceramics as shown in the photo)
2) Clay: MCS Porcelain P'Clay Cone 6 available at Baileypottery.com
Bullseye coe90 glass available at Bullseyeglass.com and other retailers
glass marbles such as Panacea Marble Accents often available at craft stores such as JoAnn Fabrics & Michael's
recycled Glass such as wine bottles, window glass, etc.
4) Items for creating texture in clay:
clay carving tools
textured objects to press into the clay including commercial stamps, found objects, buttons, etc.
5) Items for rolling out the clay:
rubber rib for smoothing clay
two 1/4" or 3/8" thick strips of wood
plastic backed fabric drop cloth, or regular drop cloth
cornstarch- I keep mine in a sugar shaker to make it easy to powder the surface of my clay
Step 1: 1. Creating the Clay Texture Mold
I've chosen a cone 6 porcelain paper clay as my ceramic medium for making texture molds because it has a very smooth surface that captures texture in great detail. The clay dries quickly, and creates lightweight molds, which is great for loading fused glass projects into the kiln and also great for storing your molds once they've been bisque fired. Most companies ship clay in 25lb blocks with a 50lb minimum. Please note that paper clays are prone to mold if not used quickly, which doesn't affect the quality of your ceramic piece, but may cause problems for people who are sensitive to mold. Most websites selling ceramic paper clay explain the pro's and con's of their products, along with firing instructions.
Decide what texture and design you're going to create. I've created wonderful texture molds from items found in my yard: lotus leaves, lily pad leaves, tree leaves. I've also hand-carved textures to create specific designs. Once you have your design in mind you're ready to start.
1. Work Surface:
Cover your work table with a drop cloth. I love using a plastic-backed fabric drop cloth because it protects my wooden work surface from the damp clay.
Open your bag of clay. Use your wire tool to cut the amount of clay you need to roll out for your project. For instance, to create the large texture mold of of the lotus leaf takes a greater amount of clay than to create a small soap dish mold.
3. Rolling & smoothing the clay:
For most of my texture molds I roll the clay out to around 1/4" thick. If you're creating a deeply textured fused glass piece like a hand-carved pattern, you'll want to roll the clay to around 3/8" thick.
Follow basic clay techniques for rolling clay by using your rolling pin to work the clay slowly into a flat consistent thickness: Roll, flip the clay over, roll, flip the clay in a new direction, roll again until you have the desired thickness and size for your mold. I try to make mine molds 1/2" to 1" larger than the finished textured design in case the glass flows beyond my design in firing.
If you come across any bubbles in your clay surface while rolling the clay, poke them with a pencil tip or clay knife tip to make sure that they're gone before you proceed with smoothing and texturing the clay.
Take your rubber rib and smooth the surface of your clay, stroking across the entire surface of the clay with the rib horizontally, then vertically. Flip the clay over and do the same procedure again, smoothing the surface of the clay with the rubber rib by stroking across both horizontally and vertically until smooth. Now you should have a beautifully smooth piece of clay, ready to decorate with your textural design.
4. Texture the clay:
Sprinkle the surface of the clay lightly with cornstarch to keep your tools and leaves from sticking. Keep in mind that you do NOT want to press or cut your design completely THROUGH the the clay. Be careful to leave at least 1/8" thickness of clay in the thinnest areas or your mold may be more prone to breaking. As you create your texture, the hollows/deeper impressions in your mold will be the raised areas on your glass surface, and the raised areas on your mold will be the hollows/impressions on your glass surface.
A) If you're pressing leaves into the surface, arrange the leaves on the surface into the pattern you desire, then roll over the surface with even pressure with a rolling pin. I then like to take my fingers and press the leaves more deeply into the surface of the clay to make a deeper impression.
B) Add carved details, rubber stamps, press in objects as desired
C) It's a good idea to create a rim to contain the melted glass by slightly raising the edges of your clay from your table.
IMPORTANT MOLD DESIGN RULES:
-Make sure that your design does not include "under-cuts", or places where the surface of the clay mold juts out over carved hollowed-out areas. The glass will melt into these areas and get stuck.
-If you want to create a thicker piece of fused glass, you'll need to create a rim to contain the glass in your mold. If you do create a rim, be sure that it gently slopes OUTWARD so that the glass will release easily out of the mold.
-The smoother your mold, the smoother the glass. I like to make sure that all of the edges of my textured pattern feel smooth, and that there are no areas in my design that could create a jagged or sharp glass surface.
5. Dry your mold:
Follow the clay manufacturer's instructions. Paper clay is very forgiving, though all clay is prone to warping if dried to quickly. I like to leave my mold on my work table for a few hours covered loosely with a layer of paper towels. Once it is firmly leather hard I carefully move it to a kiln shelf in my garage and wait until the ceramic mold is completely bone dry. During the colder winter months I dry the molds indoors rather than in the garage.
Step 2: Firing the Ceramic Texture Mold
Once the mold is completely bone dry - about 1 week for a 1/4-3/8" thick mold under normal weather conditions I bisque fire my clay texture molds to Cone 04 by following the pre-set firing schedule on my kiln. Please refer to your kiln's instruction manual for loading suggestions and firing schedules. Ceramics can be loaded into the kiln on more than one shelf, though I always make sure to have about 1/2" of space between pieces, and at around 2" at least between the tallest ceramic piece and the shelf above it.
You may remove the ceramic texture molds from your kiln when the kiln temperature has returned to room temperature, usually around 18 hours or more after starting your kiln's firing program.
Step 3: Fusing Glass Onto Your Mold
1. Kiln Wash:
Following the manufacturer's instructions apply 2-3 coats of kiln wash evenly to your mold. Allow the mold to dry between coats and especially before you start loading the glass onto the mold, or the kiln wash may stick to your glass.
Apply 2-3 coats of kiln wash to your kiln shelf prior to loading it into the kiln. This will help to protect your shelf from damage if the glass flows beyond the mold you've created, or if the mold breaks while firing inside the kiln.
2. Wash your glass:
Wash your glass in hot soapy water with liquid dish detergent, rinse thoroughly, and dry with clean towels. Bottles must have all label residue removed prior to fusing. I find a kitchen colander helpful in washing glass marbles. Fingerprints and dirty or oily residue will dull the surface of your glass.
3. Glass compatibility:
For glass to successfully melt together into a strong finished piece, it must all be of the same COE (coefficient expansion). This is a complicated issue, but can be more simply accomplished by doing the following:
a) use glass by a single art glass manufacturer such as Bullseyeglass.com 90 COE, or Spectrum's System 96 COE glass from http://www.system96.com/. These companies test all of their own glasses to be compatible.
b) use glass from one single piece of glass:
-bottles: Use the glass from one bottle only, as even bottles by the same manufacturer are not the same
-windows: Use one large sheet of glass to cut 2-3 smaller pieces of glass that you can layer onto your mold
c) marbles: I have better success using flat-sided marbles in one solid color from one large bag if possible, or bags from the same manufacturer. They're inexpensive, and widely available, though there's no guarantee of compatibility. Combining colors has often resulted in stress fractures in the glass after firing.
You can use a polarizing filter to check glass compatibility. Instructions can be found here: http://www.paragonweb.com/Kiln_Pointer.cfm?PID=221
4. Filling the texture mold with glass:
Glass wants to be 3/8" thick when melted, which means that if you fill your mold with glass thicker than 3/8" thick, it will flow and spread outward to level itself out to 3/8" thick. If you fill the mold with less than 3/8" thickness of glass, the glass may pull together into 3/8" thick areas as it melts, leaving open gaps in the glass. I have had good results filling the molds with any one of the following:
a) 2 layers of Bullseye 90COE 3mm glass, Spectrum 96 glass, or approximately 5/8" thick of compatible glass frit
b) one wine bottle- you can cut the top or bottom off of the bottle to better suit your mold size if you prefer, or make your ceramic texture mold sized to fit the entire flattened bottle
c) 2 to 3 layers of window glass (again, remember it must all be cut from one original sheet of glass)
d) 2 layers of flat-sided glass marbles are my favorite. Flat-sided marbles stack on top of each other easier than round marbles. I find round marbles must be contained within the mold by designing a higher rim around the edge of the mold, or they may roll off the mold and onto your kiln shelf.
5. Loading the kiln:
Carefully transport your project to the kiln, and place onto the prepared kiln shelf. I find glass fires best using just one shelf in your kiln, rather than stacking shelves to fire multiple layers of fused glass projects at once.
6. Firing Schedule:
The firing schedule for your project will depend on the type of glass you have used, it's dimensions and thickness, plus the desired level of melting that you're looking for. I often look to the glass manufacturer and the Internet for suggested fusing schedules for my projects, but here are a few tips and resources:
a) My favorite reference for firing schedules from glasscampus.com : http://www.glasscampus.com/tutorials/pdf/Basic_Fir...
b) The schedule I frequently follow for many of my projects (2-3 layers of marbles, art glass, or a bottle ) is as follows:
segment 1) 400 degrees per hour to 1,000 degrees. Hold for 20 minutes
segment 2) 200 degrees per hour to 1,150 degrees. Hold for 15 minutes
segment 3) 900 degrees per hour to 1,450 degrees. Hold for 20 minutes
segment 4) AFAP (as fast as possible) to 960 degrees. Hold for 1 hour
segment 5) 200 degrees per hour to 800 degrees. Hold for 10 minutes
segment 6) 400 degrees per hour to 300 degrees. 0 hold, and do not open your kiln until the temperature inside the kiln has returned to room temperature.
It's always good to have a sense of humor when working with glass, as what happens during firing inside the kiln can be unpredictable. There are entire books written on firing schedules, etc, and all kilns are a little different.
Step 4: Finished Products
There are lots of options for finishing your textured glass art:
1) Leave it as a beautiful plate
2) Create or purchase a stand for your piece. I created a stand using unfinished wood components purchased at a craft store, and painted them to coordinate with my glass art piece.
3) Slump your glass into a bowl or other shape by firing it once again in the kiln. Refer to your kiln instructions for firing schedule, or to http://www.glasscampus.com/tutorials/pdf/Basic_Fir...
4) Create an instant cake plate by finding an interesting glass candle stand with one end large enough to securely adhere to your glass art piece, and the other end large enough to support and stand steadily. Rough up the two surfaces of glass where they will meet (I use a Dremel tool). Wipe away the dust with a clean cloth, then apply E6000 glue neatly to both surfaces where the glass will meet. Wait a couple minutes, then stick them together. I often use masking tape to hold the surfaces together until the glue has set, otherwise they may slide out of position.
I hope this Instructable helps inspire you to create your own custom texture molds for original works of fused glass art.