"Really? You can do that without adding slip and they stay attached?"
"You're kidding. If I try to do that with my clay it would sag for sure."
"You cool your kiln how fast?"
Those sound like bits of conversation likely to be overheard whenever a group of potters gather. Pottery, for all its "scientific" and technological advancement, still proceeds with a great degree of intuition, guesswork, and downright magic.
Much of this is simply because of the inherent inconsistency of working with constantly changing materials that are dug from the ground and processed by less than perfect means (and then mixed and delivered to us by low-wage workers who care a bit less about quality than they do about quitting time).
But I'll bet that we all know some potter who gets away with the seemingly impossible. We all know potters who have developed a method -- or series of methods -- that we're pretty sure we'd never be able to get away with in our own shops.
It's why potters sharing information isn't just a nicety. It's survival.
It's also why I don't usually file information about processes into files labeled: "correct way to _____", and "incorrect way to ______". No, I tend to file information in files labeled: "a possible way to _______."
It is with that in mind that I mention an interesting coincidence that has occurred in just this past week. In just this past week alone I have seen the mention of S-cracks (in the bottom of pots) brought up 3 times -- once in a blog post, once in a youtube, and once in an instructional DVD.
What's more interesting is that two of those mentions were of processes that that particular potter uses to avoid S-cracks ..... and neither one of them agrees with my approach.
The first approach was one I saw in a short youtube. In the video, the potter throws and centers the clay, then cuts the centered clay off the wheel and then throws it back down on the wheel head -- topside down this time.
The second approach was discussed in an instructional DVD. Here the potter says that he takes either the extrusion as it comes out of the pugmill, or the ball of spiraled clay -- the spiral being the result of hand wedging action -- and he then throws the ball of clay onto the wheel head, making sure to keep the spiral (created either by the pug mill or by wedging) so that its vortex is the center of the wheel head.
Me? ...I do exactly the opposite from the guy in the DVD. When my clay comes out of the pugmill, I slice the clay to the usable size, and I slap the clay into a shape just shy of spherical so that I can always keep track of where the pugmill-created spiral is. I then make sure that the center of the spiral is parallel to the wheel head. I started doing this because I noticed (and you can experiment with this yourself) that if I ever take a very short, coin-shaped extrusion from my pug mill and just allow it to dry, that dry coin-shaped clay will quite often (if not always) develop an S-crack right where the spiral has trained but not quite joined the clay.
Therefore, I concluded, if I slam the side of the extrusion onto the wheelhead when I start to throw....sure, I don't (in theory) have the particles aligned for the easiest first pull possible....BUT, I do have the particles aligned along the pot's eventual bottom in a way that insures the fewest possible fault lines along which a crack might develop. And as for the particle alignment for throwing -- that all occurs during the centering process anyway.