- Porcelain is unlike other clays in both composition and behavior. I've never used it before, so it was like getting to know someone who's really really touchy, really well and really fast!
- It becomes vitreous when fired to maturity, which means that water cannot penetrate it. (And neither can glaze, which is why porcelain needs to be glazed after its Cone 04 low-fire stage. But since I decided to leave the ornament bisque, I skipped that stage and went right to Cone 5.)
- Porcelain has "memory" -- like an elephant. It means that how ever the clay is twisted, smooshed, tweaked or torked while its being de-molded or worked, it will remember that in the fire...even if you fix it before you fire it (though I have an additional theory, which I'll share later). It's definitely the antithesis to WYSIWYG! This is the primary reason why porcelain pieces are expensive -- warping and other flaws caused by this memory result in a 30%-50% loss rate. This means I had to press twice as many ornaments as I wanted to get for the edition.
- Porcelain is "sticky" -- like soft butter, unlike earthenware or stoneware, which are more dough-like. While this feel is delightful, it does present new challenges for getting it out of a press mold! I'd pondered and cogitated and pondered some more on how I was going to lift these puppies out of the mold without distorting them...until my good friend Barb gave me a great tip -- which I'll share in a bit...
But that's not all! On top of all that, all clay has to be totally dry before it can be fired. During summer here in Idaho, that usually translates to seven days of drying time. But because it was winter and the ornament was thick, they would need at least 10 days to dry before they could go into the kiln. And ideally that would be 14 days -- two weeks! And here's the kicker: Christmas was just over three weeks away! Plus, I had to get these puppies in my Etsy store at least five days before Christmas to account for shipping! There was no time to make mistakes or dawdle -- it was full speed ahead and be-darned those torpedoes.
So either this project was going to be a happy success or an epic failure. But I think it's important to take risks every so often because sometimes contemplating a project too much can create a kind of inertia. More often than not, just flinging yourself into the fray gets the gears going out of sheer panic -- and that's more potent than caffeine, lemme tell ya.
So now that you have a bit of background on the utter lunacy of this project, let's see the highs and lows of that learning curve...
Now I was presented with the puzzle of how to get the piece out of the mold -- you can see what a tight fit that is! And remember, I cannot bend or twist it to get it out -- it has to pop out in one perfect ejection. I'd thought about using my air compressor and airbrush to blow air into the mold to pop it out, but if the ornament caught anywhere in the mold, I'd end up with one big torked mess destined for the dump bucket. I needed more control. Lucky for me, my friend Barb visited earlier that week and we talked about my problem. Now she'd taken a porcelain tile making class and revealed The Great Solution the teacher taught her...use "buttons" from the pug to lift the piece out of the mold! Also luckily for me, I quickly realized that I designed my bas-relief perfectly so there were no undercuts or areas that would "catch" the piece as it was being lifted out...phew!
I used two buttons created from the scraps left over from each cutting. I dampened their bonding surface slightly with water and gently pressed them into the surface...just hard enough to create the necessary bond. Clay loves to stick to itself when wet, so that dampness created just the right amount of suction to hold onto the ornament without being permanent. I quickly found that the fresher the buttons, the more effective they held, so I just kept using those scraps created by the fresh cuttings of each slab. The old buttons simply went into the good ol' dump bucket. It took a bit of time to learn how to squish them properly, so some of the early ornaments had stronger button imprints than later ones. Working with clay really is learning the seemingly infinite "sweet spots" it demands. Interestingly, I learned that each pug was slightly different, too, presenting a new set of sweet spots. Working with mud is about being responsive and flexible to the needs of the clay -- you really can't strong-arm it. It dictates to you, not the other way around! But this actually is refreshing, since I have full and complete control in all my other creative endeavors. It's good to be humbled and submit to the will of mystery.
This technique allowed me to lift the ornament out of the mold with ease, quickly and without torking! But I had to concentrate in order to keep my two hands at equal orientations, so as not to bend or stretch the ornament while pulling it from the mold, and to transfer it flat onto the batting. After a few dozen times of doing this, it gets harder and harder...especially as those clock arms tick ever closer to the wee hours of the morning!
Here you can see an ornament about to be lifted out, along with those waiting to have their backsides cleaned with water. It takes just my finger and some water to smooth out where the buttons were. Inadvertently, I learned that if I let the ornament sit in the mold for about two minutes, it lifts easier, often just popping out. So while ornaments waited to be untombed, I cleaned up those previously de-molded.
So right when I was all puffed up over my brilliant design savvy, I realized my ornament had a big design flaw -- it had beveled edges. I was accustomed to designing bas-relief for slip-casting, and a design with beveled edges pulled better from a slip-casting mold than one with straight edges. However the reverse is true for press-molding! Getting that clay to squish evenly to those wide-spread edges became a real headache, and I decided that the press board just wasn't enough by itself -- it needed help. So I began all sorts of configurations with bits of cardboard, as you can see above. I finally ended up with #4. What was particularly troublesome was that not only did each pug behave differently during the press, but also each mold behaved differently! I can't explain why, but each definitely had a way it wanted to work best. To complicate matters, each mold can only be used for about 15 pressings at a time, otherwise it gets too wet and begins to tear the clay, so I'd have to switch to another mold to keep the pace going. All this meant my brain's memory chip was working over time between the seven molds to remember which mold wanted things which way! I suspect if anyone had been watching, they'd have seen steam flow out out of my ears. Now had I been smart, I would have labeled the molds and written down notes -- but when it's 2am and it's your third night of sleep deprivation, you just careen forward...flailing.
- Using only full kiln shelves
- Keeping the ornaments centered and away from the edges
- Running two firings instead of one big one