In this tutorial we addressed, how can we combine glass and clay, two of the oldest hand worked materials, in a digital environment? Glass and clay share many similar properties including; Earth based, the ability to be hand crafted, the work and rework-ability before the final form, the need for heat at various stages of production, and an air of mystery that still captures our attention. We wanted to highlight these similarities while exposing the differences in the materials and chose to start by 3D printing clay.
In order to complete this instructables you must have access to the following tools : safety equipment, a clay 3D printer/extruder, a kiln, a glass shop with a furnace, glory hole, and patience. Several shapes used were too small or broke during the process, so keep this in mind moving forward and work to the best of your ability!
Step 1: 3D Print a Clay Mold
Using a 3D modeling browser based or software program, create a form for the glass to be blown into. The important part is the size of the opening, this depends on the skill of the glass blower, with the larger the opening the easier. in this case both example pictures have an opening of at least 4 inches, which is a good place to start.
Printing with the clay mix of your choosing, in this case a cone 10 B-mix with grog were used to print or hand work the shape. Again an important dimension is the height of the piece, this is open to experimentation but the pieces that faired the best were pieces under 6 inches tall.
Step 2: Fire the Clay
At this point the clay needs to be fired. The firing can be any temperature, again open to experimentation, but we've been firing it to cone 04 (1940 F). Through a couple of trails and errors we have learned that firing higher than bisque added more risk to the ceramic breaking when blowing glass into it. Another side note, glazing inside the ceramic pieces is not recommended either since it will fuse to the glass and crack the piece. If its not obvious already, this is the first time you need a kiln, and depending on how many pieces you start with you might need multiple firings, which should be taken into account with time/money.
Step 3: Prepping Bisque Ceramic for Glass Blowing
Take the 3D printed ceramic forms and wrap wire tight around it, this creates compression rings to hold the piece together. This helps ceramic from cracking as the pressure applied from blowing glass into it. To aid the blowing process it helps to use a mold under the ceramic piece to "catch" the glass. This helps to control the final form the glass will take. It should be noted that this model if plaster, as shown in this example, should be coated in graphite spray to help release the glass from the mold.
Step 4: Blowing Glass Bubble Into Ceramic
Before blowing the bubble into the ceramic there are 2 things to know that we experimented with that gave us different results. The first experiment we did was heating up the ceramic to 1,000 degree and dropped a bubble into it. what we got from that was a tight bubble trapped inside the ceramic. The second experiment we did was soaking the bisque ware in water for about 5 minutes till it was fully saturated. The result was a looser bond between the glass and ceramic which has been successful from preventing the ceramic from cracking.
For these examples we did not heat the first one that ended up cracking but we did heat the second one which survived. Even though the piece cracked, the ceramic still fused to the glass because of the over hangs in the piece, so it survived, but there are too many other factors like shape and strength of the blow to correctly determine if the heating caused this piece to crack. We decide to take it as caution to make sure not to blow to hard into the next molds. This is again why we chose to make several, just in case any broke.
Glass working is a team sport, so its best to do something like this with a group of people who are on board with the process and the skills to know what to do when something goes wrong. As is seen in the next step, things do go wrong. After the glass is blown it needs to go into the kiln to cool down slowly, otherwise the glass will crack. A glass shop will have these available cost time and money.
Step 5: Lessons Learned
Things can go wrong.As previously shown one ceramic mold did crack, as did others, but this was because we were unsure of the strength of the mold against the glass and were still testing things like wire and pre-heating. One mold which was not fired was blown into and it exploded! Yes is exploded, leaving pieces of ceramic across the studio floor. This is one way to test what happens when ceramic that is not fired is exposed to 2000 degrees Fahrenheit, and does not need to be repeated anytime soon.
The glass did take the shape of the mold, and was able to be cleaned off afterwards.
Step 6: Experiment Complete
Overall the produced pieces survived from 3D printing to cold working. Each step of the process puts undue stress on each of the pieces and while several did break the majority survived and are able to be examined and worked again in a new series. More on that coming soon, stay tuned!