Edging — Dutch *opsnijden* — is a step in traditional brickmaking: the unfired clay brick is stood on its edge once the other faces have dried enough, so that the underside can dry too. At the same time the flash was trimmed off: the clay that had squeezed out under the rim of the mould.
Without this step a brick dries unevenly. The underside, lying flat on the drying floor or drying field, stays too wet while the rest has already hardened. That difference in drying shrinkage causes cracking and warping.
Where it sits in the process
The classic sequence for a handmade brick:
- Clay preparation — winning, blending and weathering the river or marine clay.
- Moulding — the clay is thrown into a timber mould. In the water-struck process the mould is wetted; in the sand-struck process it is sanded.
- Turning out and initial drying — the green brick goes onto a drying floor or drying field.
- Edging — standing the part-dried brick on edge and trimming the flash. Also called straightening.
- Final drying — until the moisture content is low enough for the brick to survive the kiln without bursting.
- Firing — traditionally in a clamp or ring kiln, nowadays usually a tunnel kiln.
Why the work was hard
Edging was classic work for children and young workers, because you had to be able to move low down between the rows of drying bricks. It was repetitive stooping work with thousands of bricks passing through the hands each day, and sore wrists were the well-known result. With mechanisation and controlled drying chambers, hand edging has all but disappeared.
What you can still see
On a handmade brick the traces of the process are often still visible: irregular arrises, a slight fold in the surface and colour differences between the faces. Precisely that irregularity is what makes handmade bricks so sought after in restoration work and in facades that need a craft appearance.
Related terms
- Handmade brick
- Brick
- Roof tile production
- Bond pattern
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