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West Lothian Archaeology Group

Brickmaking in Armadale

West Lothian, Scotland.

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Archaeology Index

Hoffmann Kiln           Canmore           Scottish Bricks

Looking north by kite from Etna Brickworks (Full Image)

Legacy o the Last Lum (of over 40)

see also

Employment and Industries

Scottish Screen Archive Film

and

Armadale Brickworks, Western Australia

 

A visit to Caradale Traditional Brick at  Etna Works, Lower Bathville in 2007:

thanks must go to John Turnbull and Carolyn Walker for their informative assistance. 

Caradale also have two operating Hoffmann kilns at Carluke, Lanarkshire (17th Feb 2009)

See also Prestongrange.

Pan mills where particles are ground before being conveyed to the loft for screening

Clay is mixed and bricks are formed

Bricks are cut before stacking to dry

A firing of bricks in the packed Hoffmann kiln

Above the Hoffmann kiln

Bricks are packed, ready in the stockyard for despatch

 

Caradale Traditional Brick, Etna Works, Production Process

(Information courtesy of Carolyn Walker)

 

Raw materials >

Raw material is brought to the works and stockpiled.  Each raw material imparts different characteristics to the finished product.  These characteristics are colour and physical properties.  Each product has a set mix of materials to produce that particular product.

Raw materials into box feeders > roll tooth crusher > 

This mix is controlled by means of motors on box feeders.  Each mix has corresponding motor settings.  Once the mix is set, the material is fed through the box feeders and is conveyed to the crusher house for primary crushing.  This is done by means of a roll tooth crusher, which consists of two rotating solid metal cylinders with protruding cylindrical teeth.  As they rotate, the material falls through and is crushed between the two faces.

Pan mills - grinding >

From the crusher, the material is conveyed to the millhouse for further grinding.  This is by means of pan mills.  Each of these mills has two large rotating steel tyres, which grind the material against a base plate as they rotate.  Once the material has been ground, it is conveyed to the loft for screening.

Loft - screening >

Screening is done by means of sizers.  Each sizer has two inclined heated screens.  The sizes of the screens are 3.15 mm and 4 mm.  Any ground particles larger than 4 mm are conveyed back to the mills for further grinding.  Once the material has been screened, the mixture is conveyed to the holding bin at the mixer.

Holding hopper > mixer > vacuum >

From the bin, the mixture is fed into the mixer.  Water ,which gives the column its plasticity, is added in the mixer to ease the extrusion of the column.  The amount of water added is guided by the amperage showing for the extruder motor.   Then, the clay passes through the vacuum chamber to remove the air from the mixture.  When as much air as possible has been removed, the column is solid and dense. The amount of air being removed is displayed on the vacuum gauge in inches mercury.

Die box >

Once through the vacuum chamber, the clay is extruded and the column is fed through the die box.  The die box determines the length and width of the green brick.  The column leaving the die box is smooth.  If another texture is desired, it is added at this point.  The drag texture is done by means of fixed blades or wires at the top and on the sides of the column.  As the column passes, the blades or wires are dragged over the surface, thereby giving the texture.  Rustication is done by means of a machine fitted with a series of revolving blades, which 'bite' into the surface of the column as it passes,  roughing up the surface and giving the rusticated texture.

Cutter >

Then, the column proceeds to the cutter where it is cut into a large block before being pushed sideways through cutting wires to make bricks.  The width between the cutting wires determines the height of the bricks.  After the bricks have been cut, they are conveyed to the setting stations.

Dryer >

At the setting stations, the bricks are built into packs, ready to be dried and fired.  At Etna Works, two kilns are in use.  Packs for each kiln are constructed differently according to the setting patterns displayed at the setting stations.

Once the packs have been built, they are placed into the dryers by forklift.  The bricks are dried by a gas-fired warm-air system, with the air being distributed by means of ducting and fans.  The bricks are left in the dryers until they are dry enough to be put into the kilns.  Normally, this process takes between two and three days.

Kilns >

Intermittent Kiln (left) and Hoffmann Kiln (right)

Once the bricks are dry, they are placed into the kiln for firing.  There are two kilns on site, the Hoffmann Kiln and the Intermittent Kiln.  The Hoffmann Kiln is a continuous tunnel kiln and is gas-fired by a portable gas system, which moves around the top of the kiln, counter-clockwise, in a 'leapfrog' action.  Three chambers are fired at a time.  Once the back chamber is fired, the burner assembly 'leapfrogs' over the front two, to the next chamber.  For example, when firing is complete in chamber 13, the burner assembly 'leapfrogs' over chambers 14 and 15 to chamber 16.  Access for the forklifts is through large doors at either end of the kiln.  The kiln is filled and emptied in quarters.  The Hoffmann Kiln holds 380,000 bricks when full.

The Intermittent Kiln below is smaller and holds 70,000 bricks.  This kiln is also gas-fired, but by means of a fixed gas burner system, and the whole kiln is fired at a time.

Packing > stockyard >

Once the bricks have been fired, they are removed from the kilns to be built into packs ready for despatch.  Bricks are built into packs using either packing boards or a monorail system.  Packs are the same regardless of whether they are built using the packing boards or the monorail system.

When using the monorail system, the packers place the bricks onto moving jigs.  Once the jigs are full, the blades are pushed through to the strapping station where protective edging is placed automatically onto each blade before it is strapped using steel banding wire.  Once five blades have been positioned correctly, the protective edging is cut at the end of the fifth blade to separate the completed pack.  The completed pack is labelled, fitted with a polythene cover, and then it is moved to the stockyard.

Bricks built on the packing boards are built in the same configuration as those built on the monorail system.  They are banded with steel strapping wire and fitted with polythene covers in the same manner as the monorail-packed bricks.

Quality checks are carried out throughout the manufacturing process as well as on the finished product.  Process checks include: particle size of the ground raw material; size checks on the extruded bricks; checks on the firing temperatures in the kilns.  The finished brick is checked for size, water absorption and compressive strength. 

Despatch

 

January 2012

 

During demolition along with its sister site at Carluke. Click on image for larger view.

The largest building on the left includes the millhouse.

January 2012

August 2012

Southern End
   
Northern End

 

August 2012

Footprints of the office block (top left), the intermittent kiln and the northern end of the Hoffmann kilns.

North eastern corner of the site. (Looking eastwards)

Near ultra-violet KAP

Looking westwards towards the former site of the millhouse which contained the pan mills (centre top).

Near infra-red KAP

Looking towards the north-eastern corner (entrance) of the site.

Hoffmann kilns footprint centre.

 

United Fireclay Products Site

A Look at the Armadale Works of United Fireclay Products, article reprint, Euroclay, Jan/Feb 1979

 

 

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