Construction

CONSTRUCTION OF UPDRAUGHT BOTTLE OVENS at Twyfords Etruria Works

Images of the construction of updraught bottle ovens at Twyfords sanitary earthenware factory in Etruria, near Hanley, Stoke-on-Trent

Bottle oven construction at Twyfords Etruria February 1921
Bottle oven construction at Twyfords Etruria
Date: February 1921

Bottle oven construction at Twyfords Etruria 1920s
Bottle oven construction at Twyfords Etruria
Date: 1920s

Bottle oven construction at Twyfords Etruria
Date: 1920s



CONSTRUCTION OF A MUFFLE OVEN at Twyfords Fireclay factory, Cliffe Vale, Stoke-on-Trent

Fireclay products for use in bathrooms are, by their very nature, very large and very heavy. A fireclay bath for instance needed to be hauled around the factory by a team of men with trolleys, ropes and pulleys.

These huge pottery products could not, therefore, be fired in a conventional bottle oven using saggars to protect them from the flames and products of combustion of the coal. No saggar wasbig enough!

Fireclay pottery needed to fired in a muffle oven.  Here the product was stacked in a chamber which was kept sealed and away from the flames and smoke of the burning coal.

These photos show the construction of a huge new muffle kiln, for firing fireclay sinks, baths and urinals at the Twyfords factory, Shelton New Road, Cliffe Vale, Stoke-on-Trent. Now demolished.


Construction of fireclay muffle oven Twyfords
Date: 1920s

Construction of fireclay muffle oven Twyfords Fireclay factory Cliffe Vale, Stoke-on-Trent
Date: 1920s




CROWN WORKS, STEVENTON PLACE, BURSLEM

Possibly an 'updraught skeleton bottle oven'  more here>


This oven was surveyed in the Bottle Oven Survey  more here> Now demolished



Crown Works, Steventon Place, Burslem.
Building cross sections of the bottle oven
Courtesy of Staffordshire Past Track here>  date: 1982





THE PERMISSIBLE HEIGHT OF BOTTLE OVEN CHIMNEY STACKS

The following comes from the (hand-written) Borough of Hanley Committees’ minutes
Held in the Staffordshire Archives, Hanley Library, Bethesda Street, Stoke-on-Trent

Works Committee Minutes – 14 February 1877
Height of Chimneys - Resolved

That the following Regulations in force under the late Bye-Laws be re-enacted pursuant to Miscellaneous Bye Law No 3, viz:
  • That the Chimneys of all Mills, Engines, Slip Kilns, and Manufactory Ovens Hovels be not less than 60 feet high.
  • That all Hardening and Enamel Kilns, Fret Kilns, and Colour Kilns, be in Hovels, or have Chimneys not less than 405 feet high.
  • That all public Bread Ovens, and Brick Ovens, or Kilns, or Brick Sheds, must have Chimneys not less than 40 feet high.
  • That no Brick Clamps be erected or fixed
That Smiths Chimneys and other Chimneys emitting larger volumes of smoke be not less than 40 feet high.
Extract taken by Paul Niblett, January 2014





MODIFICATIONS for the WAR EFFORT, DURING THE SECOND WORLD WAR

The curious caps on the top of the bottle oven stacks shown in this photograph were 'baffles' constructed on the top of ovens during WWII.  The caps were on stilts above the opening of the stack so as to allow the free passage of combustion gases from the oven. The baffle or cap masked the glow from the burning coal below and prevented ovens (being fired) from being seen by visiting enemy bombers.

Bottle Ovens - construction.  Caps built over the top of bottle oven stacks to hide glow in firing
Source: 'Potbanks' YouTube here>  Possibly Midddleport Factory Date: early 1950s




FLUES - HOB-MOUTHED DOWNDRAUGHT 


Bottle oven flues Falcon Pottery, Sturgess Street, Stoke Photo: Terry Woolliscroft   Date: May 1976 taken as part of Bottle Oven Surve
Bottle oven flues
Falcon Pottery, Sturgess Street, Stoke
Photo: Terry Woolliscroft Collection  Date: May 1976 taken as part of Bottle Oven Survey here>




BOTTLE OVEN CHIMNEY STACK ORNAMENTATION

The decorative ornamentation to the tops to all bottle oven chimney stacks was influenced by practicality, the builders preference and location.




Bottle oven chimney ornamentation Photo: Terry Woolliscroft   Date: 1975
Bottle oven chimney ornamentation
Photo: Terry Woolliscroft  Collection  Date: 1975

Bottle oven chimney ornamentation Photo: Terry Woolliscroft   Date: 1975
Bottle oven chimney ornamentation
Photo: Terry Woolliscroft Collection   Date: 1975

Bottle oven chimney ornamentation
Photo: Source unknown


Bottle oven chimney ornamentation. Chelson Street Longton
In deference to St James Church, next door, in Uttoxeter Road, Longton
Photo:  Terry Woolliscroft Collection   Date: 1970

Bottle oven chimney ornamentation
Twyfords Glost Ovens, Cliffe Vale , Stoke-on-Trent
Photo: Virtue, London   Date: 1900




1921 - Notes on THE MANUFACTURE OF EARTHENWARE by Ernest Albert Sandeman, 1921

Extracts from Chapter 13

"Down Draught Ovens have come largely into use for biscuit, as it is considered that they are more economical in fuel, and that they can be worked to produce a more regular heat all over the oven; they are also generally used in firing firebricks. 

They are constructed in several ways, some with a chamber underneath the oven into which the down-draught flues run, and from this chamber a main flue is connected with a stack or shaft standing apart from the oven, the stack being used in common by several ovens. The flue to this stack is furnished with a door that can be opened or closed at will. The oven has also a stack like an up-draught oven, but with a damper on the crown hole that can be opened or shut by a lever.

The oven is started in the same way as an up-draught oven, but when it has sufficient heat in it the damper on the crown hole is closed and the door in the flue to the outside stack is opened, and by this means the heat is drawn down into the bottom of the oven by the flues, any surplus heat passing through the chamber to the outside stack.

The name for this class of oven should be 'up and down-draught', as the course of the draught is changed during the firing from up to down and down to up, according to the heat prevailing in the top or bottom of the oven. It must be admitted that the down-draught oven is scientifically the more correct, as the gases and air have further to travel as they pass among the bungs up to the dome and are there deflected down among the bungs again to the flues in the bottom, and the combustion is more complete.

Prima facie, this, coupled with a diminished consumption of fuel, would indicate that this class of oven is the best, but it has to be taken into consideration that the first cost of downdraught ovens is heavier, both owing to the arrangement of the flues and to the extra stack outside, and that they require far more repairs, and that these repairs are more costly to carry out than in up-draught ovens. In fact it is often difficult to locate a stoppage in a flue without pulling down a lot of brickwork; added to this, they require more attention in firing. Messrs. Minton's and Roby's patents are reckoned some of the best in this class of oven.

These ovens may also be built with a big flue instead of a dome underneath, and also, to avoid the expense of an outside stack, a wide flue may be carried up the up-draught stack outside and joined into it above the damper; but the draught obtained by this means is not sufficient, and if several ovens are to be built on the down-draught system it would probably be cheaper to build an outside stack in connection with them all, and the working results would undoubtedly be better."  

More about oven types here>




BOTTLE OVEN REPAIR and MAINTENANCE

RIDDING This was an essential process in the life of a bottle oven. It entailed the thorough repair and relaying of the flues, oven bottoms, and bags. This was a major operation which put the oven out of use for some considerable time. It needed to be done every three years or so - depending on the work that the oven had been put to. In 1920 ridding would cost around £30.

REBUILD A complete rebuild of a bottle oven, excluding the hovel, was required, on average, every 20 years.




BOTTLE OVEN BUILDERS of THE POTTERIES

Wengers Ltd,  Etruria, Stoke-on-Trent
H. Howlett and Sons, Hanley. "Specialists as oven and kiln builders."
Mountford Kiln Builders





WENGERS "THE ERECTION OF OVENS AND KILNS"




Download pdf here>





Building the ‘crown’ dome of the bottle oven.

How a South Wales bricklayer did it at Winchcombe Pottery, 1930s
Description courtesy of “A Pioneer Potter” by Michael Cardew 

“All he needed was a supply of plain firebricks, a good fireclay mortar, and a boy to hand him the bricks. His first step was to dismantle the old dome. I expected it to collapse suddenly, more or less at a touch, but was surprised to see that he had to take it down brick by brick. Next he built himself a platform on which to stand. Then he complained that the new firebricks I had provided were wet, so we hastily found dry ones for him. Standing now on his platform he took time to prepare a good surface - a smooth circle, sloping at 45 degrees - from which to ‘spring’ the dome.

He then proceeded to lay the first two bricks lying side by side on this 45 degree slope. To my surprise, they stayed there, and did not slide or fall. He went on, laying brick after brick until the first circular course was complete, Cutting the last brick to fit tight into its space and ramming it home like the keystone of an arch. The whole circular course of bricks was now firmly locked in position and he immediately went on to the second, the third and all the other courses, which he laid in exactly the same way.

He had built so many domes that his eye was trained and he was able to dispense altogether with the trammel or guide stick. He provided for the holes at regular intervals by laying one brick ‘dry’ without mortar standing up a few centimetres above the others; when the dome was complete he went inside with a hammer and knocked out the dry-set bricks to leave holes. As the work progressed towards the centre the angle of the bricks became more nearly vertical, but since the circles were now smaller they locked each other more securely.

For the last few circles he left his platform and worked from the top, standing on his own uncompleted dome; for the last circle of all he had to cut most of the bricks to a tapering wedge shape, leaving at last a central hole about 9 inches across.”




Some Terminology

BATTER The description of the slope given to the shape of the brickwork of the hovel of a bottle oven. Batters can be stepped or flat. Church batter is curved and real bottle shaped. Straight batter is truly conical.

BATTER RULE Equipment. Used by a bottle oven builder as a measuring device. Used to give the required slope on the hovel. Sort of a protractor. (Mountford, kiln builder)

For definitions of unusual Potteries words go to The Potbank Dictionary here>