# Assembling Hard Slab Forms

Unit: Handbuilding Basics
Topic: Hard Slab Construction
URL: https://claybook.studio/learn/assembling-hard-slab-forms/

# Putting It Together

Now comes the satisfying part: assembling your cut pieces into a three-dimensional form.

## The Assembly Process

1.  **Plan first**: Lay out all your pieces on the table before joining anything. Make sure they fit.
2.  **Score and slip**: Every join needs it: no exceptions (more on this in Topic 5).
3.  **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.
4.  **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](https://en.wikipedia.org/wiki/Clay_minerals) layers. The coil-reinforcement technique for inside corners works on the same principle as a [fillet weld](https://en.wikipedia.org/wiki/Fillet_weld) in metalworking, adding material at the stress point to distribute load.

## Check your understanding

### Question 1: How do you reinforce the inside corners of a slab box?

- [ ] A. Apply extra glaze
- [x] B. Add a coil of soft clay and blend it
- [ ] C. Tape the corner from outside
- [ ] D. Nothing, corners are strong enough

Tip: Press a thin coil of soft clay into each inside corner seam and blend it in with a tool.

### Question 2: Why should a lid be cut slightly larger than the box opening?

- [ ] A. So it looks more decorative
- [x] B. To account for clay shrinkage
- [ ] C. Larger lids are easier to lift
- [ ] D. It prevents warping of the box

Tip: Clay shrinks 10-15% as it dries. If the lid is the same size as the opening when wet, it will be too small to fit after shrinkage.

### Question 3: You are assembling slab walls and corners keep drifting. What helps most?

- [ ] A. Assemble faster before slip sets
- [x] B. Use supports or a 90-degree jig while drying
- [ ] C. Skip reinforcing coils to reduce weight
- [ ] D. Dry uncovered under a fan

Tip: Use temporary supports or a 90-degree jig while seams set. Mechanical support keeps geometry accurate during early drying.