Agriculture Reference
In-Depth Information
H.G. Matthews, Buckinghamshire
H.G. Matthews are a well-established family firm of traditional brickmakers
established in 1923, and produce between 50-70,000 bricks per week of which
15-25,000 are handmade. During the last decade the company has occasionally
produced bricks capable of being rubbed. The intention of the company is to
produce a rubber by modification of the clay preparation and firing techniques.
James Matthews of H.G. Matthews and Andrew Hales his head brickmaker,
have taken the lead in this initiative and in consultation with the author,
agreed to focus on clay preparation and firing. For the clay preparation it
was deemed necessary to increase the sand ratio, and to look at washing and
screening the clay. It was agreed in this respect that the company would look
at producing a washed and unwashed rubber, with the intention of achieving
a broader range of bricks for aesthetic matching to different historic periods.
With regard to firing, they were determined to fire at 900ºC, and to seek to
position the rubbers in the stacking arrangement within the kiln to maximise
the potential of the firing process to produce quality rubbers.
Their orange through to dark-red standard handmade facing brick is called
a Chalfont Red and is made from a mixture of Chalfont Clay and natural sand.
This clay sits within a 6.5 metre seam about one metre below ground level.
Machine excavation is seasonal and the won clay is mixed 50/50 in the pit or
knott-hole. The blended clay once moved to the works is then stored for wea-
thering for as long as possible. When required a given amount is drawn down
by mechanical digger and a 'soak' is created, whereby water is added which
overnight is absorbed so that the material becomes more malleable. On the
day of use the 'soaked' material is turned over by the digger to crudely mix it,
this is then taken to the single-shafted mixer to be pugged.
The pugged clay is taken by conveyor belt to a set of crushing rolls, the top set
having a screw thread profile draws the large pieces of integral flint waste within
the mix away to an awaiting container. The residual clay then falls through to
a small set of smooth-faced twin rolls crushing any remaining inclusions creat-
ing a clean-bodied and workable material. This is then taken by conveyor belt
to the hand-moulders' benches. The brickmaker removes his clot of clay from
the large pile deposited on his bench. This clot is rolled in sand and thrown in
to the pre-sanded teak timber mould, the excess trimmed off with a metal strike,
and the mould tapped and turned to eject the brick cleanly. The green moulded
rubbing bricks are placed on stillages under a wooden frame covered with cor-
rugated Perspex to naturally dry for 12-14 days in ideal conditions; in the winter
months drying is aided by the use of computer controlled oil-fired blowers and
electric fans.
The burning takes place in a gas-oil fired, up-draught scotch kiln with a
capacity for 70,000 bricks. The firing temperatures are between 900ºC and
