Lids That Mostly Fit (I'm Honest About My Seventy Percent)
Okay, so you've got a box now. Walls joined clean, base solid, maybe even feet on it. This is the lesson where I have to be straight with you before we start: lids are the part of handbuilding I still haven't mastered. I've been doing this five years and my success rate on a lid that sits right, sits flush, and doesn't rock or gap, is maybe seventy percent. I'm telling you that up front so that when yours doesn't fit perfectly, you don't think you did something wrong that I know how to avoid. I don't. We're both in here figuring it out.
Here's the thing about lids, though. The reason they're fiddly isn't mysterious. You're trying to make two separate pieces of clay, made at different times, shrink at the same rate and land in the same place. Clay has opinions about that and they aren't always yours.
Measuring the opening
Before you do anything else, measure the actual opening of your box, not the outside edge. Use a ruler or a strip of paper laid across the rim. Write the number down. I mean this. Do not trust your eye and do not trust your memory from five minutes ago, because clay shifts as it firms up, and the box you measured before lunch is not exactly the box you're looking at now.
Building the lid slab
Roll a slab the same thickness as your box walls. Cut it about a quarter inch bigger than your opening measurement on all sides if you want an overhanging lid, or exactly to size if you want a flush inset lid that drops down into the box a little. I like overhanging lids for beginners because they're more forgiving. A flush lid that's off by an eighth of an inch looks off by an eighth of an inch. An overhanging lid hides a lot of sin.
Let this slab firm up to the same leather-hard stage as your box before you do the next step. Same stiffness, same day if you can manage it. This is where lids go wrong most often, and it's the same lesson I keep repeating: our air here is dry, we're up around 4,600 feet, and things skin over fast. I lost an entire batch of bowls once because I stepped away to answer a work email and came back to slabs that had crusted over and cracked while I wasn't looking. Ten minutes. That's all it took. So cover your lid slab and your box under plastic the second you're not actively touching them, even if you're "just going to grab water real quick." I buy the giant multipack of shower caps at Costco for exactly this. Not for the shower. For clay. Fits right over a bowl or a small box, keeps things at an even moisture level, and nobody in the checkout line questions why you're buying forty of them.
The flange, if you're doing one
If you want the lid to seat itself instead of just resting on top and sliding around, add a flange. That's a strip of soft clay, coiled and joined to the underside of the lid, sized to fit just inside your box opening. Score and slip that join like every other join in this class. No exceptions. I don't care if it's a small piece and it seems like overkill for something this size. I've watched flanges pop clean off in the kiln because someone decided this join was too minor to bother with, and then the lid doesn't work at all, so you skipped the shortcut and lost the whole feature.
Cut the flange strip a little smaller than the opening, not exact. Clay shrinks unevenly and a flange cut to the exact opening measurement will, by the time it dries, either be too big to fit or so close a fit that it grabs the walls and cracks something as it shrinks against them.
Fit, but don't chase perfect
Once it's dry enough to test, set the lid on and see how it sits. It will probably rock a little, or gap on one side. Here's my honest opinion on this part: don't chase symmetry to fix it. A lid that's slightly irregular, that has a little personality to the way it meets the box, reads as handmade in a good way. A lid sanded and fussed into mechanical perfection usually just reads as trying too hard. Fix actual problems, an obvious crack, a corner that won't sit down, a gap you can slide a finger into, but don't sand away every trace that a human made this.
If the fit is really off, more than a sixteenth of an inch of daylight showing, that's worth adjusting before bisque. After that it's mostly out of your hands until glaze fire, and glaze can hide a multitude of small sins if you're not piling it on.
Before next time
Bring your box and your lid slab to the same stiffness before our next session, even if that means covering one and letting the other catch up under plastic overnight. We'll trim, test the fit, and talk about what to do when it's close but not quite there, because close but not quite there is where most of us live with this one.
~erin