Putting It Together
Now comes the satisfying part: assembling your cut pieces into a three-dimensional form.
The Assembly Process
- Plan first: Lay out all your pieces on the table before joining anything. Make sure they fit.
- Score and slip: Every join needs it: no exceptions (more on this in Topic 5).
- Join one wall at a time: Hold the first wall against the base and press firmly along the inside seam. Blend clay inward with a finger or tool to reinforce.
- Support while drying: Use wadded-up newspaper or small clay supports inside the form to hold walls at 90 degrees while they set.
Reinforcing Corners
The inside corners of a hard slab box are vulnerable. Roll a thin coil of soft clay and press it into each inside corner seam. Blend it in with a tool. This dramatically strengthens the join.
The Warping Problem
Flat slabs want to warp as they dry unevenly. To prevent this:
- Dry your finished piece slowly under loose plastic.
- Set it on a piece of foam or batting that allows slight movement.
- Make sure slabs are evenly thick: uneven slabs warp more.
The Shrinkage Factor
Clay shrinks as it dries (usually 10–15%). If you are making a box with a lid, account for this: the lid should be cut slightly larger than the opening, so it still fits after shrinkage.
Assembly Quality Check
After joining, verify:
- Corners are square with a jig or ruler.
- Inside seams are blended and reinforced.
- Wall thickness is similar on all sides.
- Piece is covered loosely for slow, even drying.
This is where premium-looking slab work is won or lost.
Pro Tip
To get perfectly square corners, build a simple cardboard jig: two pieces of cardboard taped at 90 degrees. Use it to check each corner as you assemble.
Go Deeper
Clay typically shrinks 10–15% during drying and firing, a property governed by the water content between clay mineral layers. The coil-reinforcement technique for inside corners works on the same principle as a fillet weld in metalworking, adding material at the stress point to distribute load.
