So what's pressed brick then?

Let's get technical ...


Pressing is the traditional technique used to make bricks and terracotta. Clay is pressed by hand into moulds. See, very technical.

The idea is that as the clay is smeared and pressure is used to fill the mould the clay is compacted and any air is forced out of the clay, thus making the end product consistent and strong. Once filled, the moulds are left to allow the clay to dry. Over a few hours the moisture in the clay ia absorbed by the porous plaster mould, the small amount of shrinkage that occurs is enough to allow the pressed clay piece to be popped out of the mould. Some finishing by hand is usually required to tidy up any seams of signs of pressing visible.

The National Terra Cotta Society of U.S.A Standards gives more detail in the Pressing section of their Brief Synopsis of the maunfacture of Terra Cotta :

This is a manual process and consists of pressing the plastic clay into the mould. The walls of the pieces should not be less than one inch thick, following the contour of the mould, and the partitions should be of such a thickness and so spaced as to perform their proper functions with regard to form and structure. The pressed piece remains in the mould until the clay stiffens. It is then removed from the mould and is skillfully retouched. Then it is placed int he driers where the moisture is evaporated.

See below for the full document.

Pressed chimney pot from Whittleford Park heritage project

Bricks are traditionally thrown. Clay is literally thrown into a mould, the force and momentum with which the material strikes the mould both forces it into all the corners and expells any air in a similar way to pressing by hand. Bricks are often now mechanically made.

Dust pressed tiles at Craven Dunnill, Jackfield

A lovely technique for making tiles is dust pressing. This is quite a different technique and indeed material. Clay in powder form fills a tile mould, a machine applies pressure and the clay plasticises and becomes solid. The effect is a very fine finish and very little shrinkage. Very clever.

from Boston Valley Terra Cotta website