Wedging the Clay So There's No Air Trapped in It
Before you touch the wheel, you touch the table. This is wedging, and it's boring, and I'm not going to pretend otherwise. It's also the reason your pot either survives the kiln or explodes in it, so we're doing it anyway.
Here's the problem we're solving. Clay comes out of the bag with air pockets in it. Little bubbles from being pugged, mixed, slapped into a bag at the factory. You can't see them. Doesn't matter. If you throw a pot with an air bubble trapped inside the wall, one of two things happens. Either it makes centering miserable because the clay bulges weird under your hands, or it survives all the way to the kiln and then the trapped air heats up, expands, and pops the piece apart during firing. I've seen a bisque shelf with a piece that blew a chunk clean off it. Nobody wants to lose three weeks of work to a bubble the size of a pea.
Wedging pushes that air out before you ever sit down at the wheel.
The method I actually teach
There are a couple of fancy wedging techniques out there, spiral wedging being the famous one, where you work the clay in a rhythm and it ends up looking like a little clay shell when you're done. I'll show it to you. Some people love it. I am not one of them, if I'm honest. My spiral wedging looks more like a lump that got nervous.
What I teach instead, and what I use myself every single time, is the ram's head method, because it's harder to mess up.
- Cut your clay off the block with a wire tool, about the size you'll need for what you're making that day.
- Set it on a canvas-covered table or a plaster bat. Not bare wood, not your kitchen counter at home unless you don't mind clay stuck in the grain.
- Push the clay down and forward with the heel of both hands, rocking your weight into it, then pull it back toward you and fold it over itself.
- Rotate the clay a quarter turn and do it again. Push, fold, quarter turn. Push, fold, quarter turn.
- Keep going until the clay makes a shape like a ram's head, rounded on one end with a little fold pattern on the sides. That shape isn't decorative. It's what happens naturally when you're doing the motion right.
- About fifty to eighty wedges for a fresh bag of clay. Recycled clay that's been reworked a bunch, give it more. When in doubt, do more, not less.
You're listening for a change in sound almost as much as feeling it. Air-pocketed clay sounds a little different when you slap it down, kind of hollow. Once it's wedged out, it sounds denser. You'll hear the difference after a few weeks, I promise you won't hear it today, and that's fine.
Wet hands here too
Same as I said about the wheel itself, I run wetter than a lot of instructors teach. Keep a little water on your hands while you wedge if the clay's on the dry side. Dry hands drag and tear at the clay surface instead of folding it clean, and torn clay traps more air, not less. That's just my preference, stated as a preference, but it's one I hold onto.
About the magic ring
I have to tell you about the magic ring technique, because you'll hear about it eventually, probably from someone in a video who swears by it. It's a way of opening your centered clay using a coring motion that supposedly saves you a step and gets a cleaner interior wall. Somebody swore up and down it would change how I open clay. I tried it. Did not work. Tried it again a few weeks later, figuring I did it wrong the first time. Still didn't work. I've probably tried it five separate times over the time I've been doing this and I still can't get it to behave for me.
So I'm not going to teach it to you like it's the secret handshake of pottery, because for me it isn't one. I'll teach you the plain, direct way to open clay once we're at the wheel, the way that's never let me down. If you find a video on the magic ring later and it clicks for you, great, go for it. Just don't think you're missing something essential if it doesn't. I'm proof you can throw a decent pot without it.
The one real caution
Watch your wire tool when you cut clay off the block. It's just a length of wire with two handles, cheap, maybe two bucks, but it's tight and it moves fast through clay. Keep your fingers clear of the line as you pull it through, and don't let it snap back at you. Nothing dramatic usually happens. I just want you paying attention to it instead of chatting while you cut.
Before next time
Wedge a fist-sized lump of clay at home if you've got some, even just to feel the rhythm of push-fold-turn. If you don't have clay yet, that's fine too, just picture the motion so it's not brand new in your hands next week.