The bowls I have attempted seemed to have created almost as much drama as my bibles. In fact, as I sit here writing these notes, I have no idea if any of my bowls will survive the current firing–either in float glass or soft!
We have only about 1 month before Christmas break and so many assignments to complete. Some of what I have worked on this term, may have to merely be carried over to the winter term. And I guess that I can live with that!
Here are my wax forms. I had 3 bowls that left me wanting some excitement. I began stacking the bowls and made them into a vase (which I liked alot). However, as you can see from the finished float or plate glass piece here, my glass did not fully melt to satisfy allowing the glass to flow all the way to the bottom of the plaster.
I need to mention here that before anything got done, I had some major setbacks in accomplishing these bowls.
One of the molds leaked into the kiln and as a result, the element broke and the kiln is out of action.
What also shows from the picture of the flower pot is that the glazing on the pot does not work well as a reservoir for glass. It was therefore a poor choice of glass reservoir on my part.
The resulting piece you see here came out of the mess shown above.
Still, you can tell by the colour that this plaster mold contained float glass.
In the program I used with the float glass, what can be belatedly noted was that the melting temperature for float glass needs to be set somewhat higher than 850 degrees Celsius (perhaps 900 or 950 is more realistic for this much glass).
Also what we are beginning to figure out is that the reason for my cracked molds seems to stem from my inadequate allowances for drying out — while the firing is gaining heat.
My molds are quite often (but not always) done while the mold still has a great deal of moisture. The period calculated for drying is supposed to happen long before I reach 600 degrees Celsius. I had misunderstood and was working to have the moisture vented out of the kiln by the time it reached 600 degrees. What I now realize is that by the time it passes from 120 degrees, there should be only the slightest bit of moisture (known as chemical moisture) showing on a clean piece of glass where the kiln is slightly opened. Chemical moisture does not typically dissipate from a piece until it reaches the 600 degree mark.
The steps to this input were actually included as of November 27. The firings took place as far back as October 31. I was using kiln #2 and set the firing to begin as of 2 pm.
I have learned so much from the time I initially began to write and submit these pages until now!
- 4: hrs ^ 90 degrees
- 14: hrs ^ 110 degrees
- 26: hrs ^ 120 degrees
- 34: hrs ^ 600 “
- 38: hrs @ 600 “
- 38:01 ^ 850 “
- 52: hrs @ 850 “
- 52:01 hrs 540 “
- 68: hrs @ 540 “
- 90: hrs 400 “
- 110: hrs 50 “
Let’s move on for the next couple of days….
For our next more current effort, we put lots of blocks in to prevent the form from breaking and leaking if any cracks develop.
My pics aren’t showing that when I set up the kiln #4 for firing on November 2, I got shut down by my program head just prior to reaching 600 degrees.
The mold had not sufficiently dried out to satisfy his piece of mind. So Koen had me shut down my program because he could see cracks beginning to appear in my mold and did not want a repeat performance of me downing another kiln from leaking glass. That was a fortuitous moment!
I have adopted an attitude that whenever one of my instructors gives me a direction order, I follow it–no matter how stressful it may appear to achieving my goals (in that specific moment). I am so glad that I follow that mindset every time.
- 3: hrs ^ 90 degrees
- 12: hrs ^ 110 “
- 29: hrs ^ 120 “
- 35: hrs ^600 ” ** **This was just about to happen when
- 37: hrs @ 600 ” Koen had me stop the program and so
- 37:01 hrs ^ 850 ” this part never actually ran as you see it
- 50: hrs @ 850 ” here.
- 50:01 hrs 516 “
- 80: hrs 516 “
- 105: hrs @ 390 ”
- 125: hrs 50 “
Some days later–November 7, Orion & I packed a different kiln #2 for firing at about 3:pm using soft glass.
Same mold but now the things is totally dried out so drying is not the issue here…
- 2: hrs ^ 100 degrees
- 7: hrs ^ 120 “
- 12: hrs ^ 600 *** Again we were foiled at this point
- 15: hrs @ 600 ” of temp. in a different kiln
- 15:01 hrs ^ 850 ” Before resuming, the temp actually fell
- 28: hrs @ 850 ” back to about 400 degrees Celsius
- 28:01 hrs 516 “
- 58: hrs @ 516 “
- 103: hrs 390 “
- 148: hrs 50 “
However…. there was an issue. I happened to notice that the kiln stayed at just under 600 degrees Celsius for longer than the allocated time of 11 + hrs. It took me about 2 days to realize that it had stopped heating and was waiting for me to realize some other problem had developed.
Again Koen told me to crash the program while waiting for an answer. Jason was not yet arrived for the day and without my kiln casting instructor to consult, Koen’s first line of defense is “shut it down” and wait for Jason to fix it.
Luckily, Jason arrived within the 1/2 hr and figured out that one of the elements had failed and was preventing the kiln from reaching maximum heat. He was able to fix the problem and set my kiln to holding while I re-input a modified program.
Final programmed steps:
- 0.01 hrs from 400 – 600 degrees
- 3: hrs @ 600 degrees
- 3:01 hrs ^ 850 “
- 18: hrs @ 850 “
- 18:01 hrs 516 “
- 48: hrs @ 516 “
- 90: hrs 390 “
- 138: hrs 50 ”
Those flower pots shown at the top of the plaster were to hold (hopefully) enough of the clear soft glass (note the lack of green tinge) to fill the form. As of the final writing (November 27), the flower pots had completely emptied without mishap (no glazing so no cracking from incompatibility problems).
However, then one of the elements failed while the kiln was firing to melting point and so we were lucky enough to have a technical assistant who could work his magic–even while the kiln was loaded and hot.
When I last looked inside the kiln, those pots were empty of glass but they were glowing red–just prior to the temperature falling back to cool.
In the final analysis, I have decided to make a small fountain out of my piece to offset some of the things that took place within the piece itself. Plaster got trapped inside some of the glass while things moved that weren’t intended to move.
I had used wax to form my bowls; but clay to form the platforms holding the bowls together. That is an issue of developing skills to work with wax. As of this writing, I have begun to make more bowls that have no clay as part of the form so that when I melt the wax from the plaster mold, it will be just wax I am trying to remove. Some of my clay got stuck and never did make it out of the form.
In closing off at this point, I should also mention that Jason has since found time in his very very busy schedule to replace the broken element of my previous glass mishap. We are no longer down by 1 kiln.
STAY TUNED WHILE I ATTEMPT TO MAKE MORE BOWLS… MORE FOUNTAINS, ETC.