Monday, April 30, 2012

Fickle fipples

The Durham spring Art Walk was this past weekend, and I spent a few hours on Saturday in front of Claymakers, providing wheel demos for passersby. I made chickens: they're quick and cute, and they offer great opportunities for one-liners. I used to demo chicken rattles, but of course this year I made chicken whistles, which facilitated pleasant cooing interactions with some morning doves in the awning above the door.

By the end of the afternoon, I had a bat full of chickens waiting to be transformed from single-note birds to full-octave gals, so on Sunday I spent a few hours on voicing.

The only annoying thing about making  full-octave ocarinas is that while an ocarina might start out with a lovely clear tone and might hold onto that tone through the addition of a few finger holes, at some point you cut one hole too many and the clear tone vaporizes: poof, gone. The quickest fix is to plug the last hole, but that's not an option if you need the hole for building a diatonic scale.

Ocarina fipples* are fickle, fickle, fickle, and predicting and diagnosing fipple problems is difficult because so many variables are involved: number of holes in the resonating cavity, hole sizes (a hole that is too small can muffle the tone), distance from windway exit to labium,** bevel angle, bevel thickness, windway channel shape/size, changes in the fipple due to condensation (when you blow through the mouthpiece to test the tone, water from your breath condenses onto the clay), stray clay goobers that obstruct the windway, etc. Once a chicken becomes breathy, it's often easiest to fix tone problems by hand-building a mouthpiece and attaching it to the bird butt, rather than trying to adjust a built-in windway (i.e. a windway that is one with the chicken), but attached mouthpieces sometimes shift during drying, and even a slight change in angle can obliterate the tone again.

Recently I've been having pretty good luck with built-in windways, but I still lose the tone around the sixth or seventh finger hole. Today it finally occurred to me how to fix the problem.

Several online ocarina-making instructions say the bevel angle should be 45o, which in practice isn't the case--certainly not when an ocarina produces just a single tone. However, because the bevel is the thinnest part of the fipple, it dries faster than the rest of the ocarina. I noticed that ocarinas that had been well tuned were turning breathy after drying a bit, and guessed that the drying bevels might be shifting upwards, changing whatever angle happened to be working when the chickarina was first voiced. Gently pushing the bevel down fixed the problem. I transferred that solution to the chickarinas that were losing tone quality with the addition of finger holes and discovered that pushing the bevel down usually repairs the sound. When that fix doesn't work, an added mouthpiece does.

I expect this is going to save me hours of mouthpiece futzing. Another trial-and-error breakthrough in the geek lab, where I continue to fill gaps the world never knew it had.

*Another bonus of making ocarinas is getting to use technical terminology like fipple and labium.
**Monday night update: According to the Wikipedia article on fipples, the bevel of a fipple is called the labium lip. The term labium lip is redundant, of course, since labium is Latin for lip, so I'm editing the term down to just labium. I suppose I could pare it down to lip instead, but labium and fipple sound intriguing together, while "lip and fipple" sounds like a '70s comedy team.

Friday, April 20, 2012

Pottery photos

The postmark deadline for Lark's new 500 Teapots book is today, and in about ten minutes, I will go to the post office to mail off four photos taken by a friend, professional photographer Adrian Moreno. I also wanted to submit a detail photo for one of the teapots, but I didn't have any from Adrian and--procrastinator that I am--didn't leave time to ask him to take any. Having also procrastinated about that 2010-into-2011 New Year's resolution to build a workable set up for photographing my pots, I ended up spending this morning futzing with my old dented Canon PowerShot A620, trying to get some good close ups. I took the teapot outside for some natural partly cloudy light and took about 100 pictures. I learned a lot about glare and the complete randomness of getting the microphotography feature to actually focus, developed an increasingly steady hand (I was too lazy to get out a tripod, but not too lazy to take 100 photos), and ended up with this:

It looks a little sharper after it's run through an "autocorrect" filter, but the submission guidelines say not to do that, so that's that. I'm impressed by the detail of the crystals; thanks to the photo, I'm noticing details on the pot that I'd never seen before.

In other photograph submission news, I sent some shots of assorted geek pots to the 2012 Bridges conference on math/art intersections, and they were accepted! Charlie Evergreen took the first two photos below. I took the third--yes, I need to work on that photography set up--yet it's the tori that are going into the month-long (vs. conference-long) exhibit in Towson's College of Fine Arts gallery. Just goes to show what happens when mathematicians instead of potters evaluate your work.