Construction

A bottle oven or kiln is a brick-built, bottle-shaped structure in which pottery, or its component materials, were fired. 

The simplest type of bottle oven - the updraught hovel oven - consists of two main parts:

1) The Hovel 

The outer part is known as the hovel. All hovels had one distinctive and common feature, the bottle shape. This shape, with its wide base and narrow neck, evolved to accommodate the firing chamber together with room for men, materials and equipment. The tapering chimney was better for creating draught which aided the firing process and helped to take away smoke. It also improved protection from bad weather. In order to take away the thick black smoke created during firing, Local Byelaws, passed in 1877, stated that hovels should be not less than 60 feet high. Some could be up to 70 feet (21m) high. 

Hovel bottle oven
at Gladstone Pottery Museum Longton, Stoke-on-Trent
Photo: unknown source   Date: 2019

2) The Firing Chamber 

This is the inner part of the bottle oven. It is a cylindrical structure with a domed roof. Its walls are about 12" (30cm) thick. The domed roof is called the crown. Iron bands, known as bonts (or bontings), run right round the chamber at about 12" (30cm) intervals to strengthen the brickwork as it expands and contracts during firing. 

Bonts surround the oven to give it strength
Fixing brackets and bolts ensure a good tight fit
Photo: Terry Woolliscroft Collection  Date: 2018

The doorway to the chamber, is called the wicket. For the most common ovens it is just about tall enough for a man with a saggar balanced on his head to pass through. Some specialist ovens, such as those which can be seen at the Acme Marls factory at Bournes Bank, Burslem, were only tall enough just for the man to pass through, without the saggar. These ovens were used for firing refractory products, such as kiln furniture, which was carried into the kiln at waist height. The wicket is surrounded by a stout cast iron frame. 

Height of the standard wicket -
tall enough for a man with a saggar balanced on his head
Seen here - Jim Evans, the fireman
at W.T.Copeland, Stoke

Around the base of the firing chamber are firemouths (the exact number depends on the size of the oven) in which coal fires were lit for the firing. Inside the oven there is a small chimney, called a bag, over each firemouth. The bags carried hot gases and intense heat from the fire into the oven's interior. Flues underneath the upwardly sloping floor of the oven, leading from each firemouth, distributed the heat throughout the inside. In the centre of the oven floor is the well hole. 

Each bottle oven had its own 'character' and firemen had to learn how best to work with them and to control the way they performed and fired.

No two bottle ovens or bottle kilns were (and are) alike. They were all built differently, many without any architects' drawings or plans. Many were built 'by eye' and based only on the experience of the oven builder and the requirements of the factory owner. 'They just went up'. The decorative brickwork at the top of the hovel varied on the whim of the builder and owner and may have been a kind of trademark.

CONSTRUCTION OF UPDRAUGHT BOTTLE OVENS at Twyfords Etruria Works in 1921

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
Date: February 1921

Bottle oven construction at Twyfords Etruria
Date: 1920s

Bottle oven construction at Twyfords Etruria
Date: 1920s

"Twyfords Ltd. Hanley. New Earthenware Pottery View of Ovens"
Date: 1920s

CONSTRUCTION OF A MUFFLE KILN at Twyfords Fireclay factory, Cliffe Vale, Stoke-on-Trent in the 1920s

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 was big enough!

Fireclay products such as baths, mortuary slabs, sinks and urinal stalls, needed to fired in a large muffle kiln.  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 kiln
Twyfords Date: 1920s

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

CONSTRUCTION DRAWINGS - CROWN WORKS, STEVENTON PLACE, BURSLEM

Possibly an 'updraught skeleton bottle oven'  more here>
This oven was surveyed in the Bottle Oven Survey  more here> 
Demolished, late 1970s.

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 CHIMNEYS

The following comes from the (hand-written) Borough of Hanley Committees’ minutes, stored 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 40.5 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 Middleport Factory  Date: early 1950s

FIREMOUTH TYPES

The design of the firemouth for a potters' updraught or downdraught bottle oven could either be : 

A) With a vertical feed hole, with 2, hinged, cast iron firedoors
B) With a vertical feed hole, with 2 sliding fireclay slabs
C) With a horizontal hob-mouth feed hole, with sliding fireclay slabs

A. Vertical feed hole, hinged firedoors

This type is the most common now found on the remaining bottle ovens in Stoke-on-Trent. Firemouths were built into the side of the oven. They each have a vertical feed hole where coal is baited (shovelled) onto the fire bed. The hole can be closed off, partly or fully to regulate the flow of air to the fire, by means of two hinged cast-iron doors suspended from robust ironwork surrounding the firemouth. Good examples of this type of firemouth can be see at Gladstone Pottery Museum, Longton, or Moorcroft Pttery, Cobridge . 

Vertical firemouth, vertical feed hole, firedoors open
Last Bottle Oven Firing
Cold firemouth, lumping
Photo: Brian Colclough Collection  Date: Aug 1978

Vertical firemouth, vertical feed hole, firedoors open
Last Bottle Oven Firing
Cold firemouth, lumping
Photo: Brian Colclough Collection  Date: Aug1978

Vertical firemouth, vertical feed hole, firedoors open
Last Bottle Oven Firing
Just after peak firing
Photo: Brian Colclough Collection  Date: Aug 1978

Vertical firemouth, vertical feed hole, firedoors closed
Last Bottle Oven Firing
Photo: Brian Colclough Collection  Date: Aug 1978

B. Vertical feed hole, no hinged firedoors, with vertical sliding fireclay slabs

This type can be found on some of the remaining bottle ovens in Stoke-on-Trent. Firemouths were built into the side of the oven. They each have a vertical feed hole where coal is baited (shovelled) onto the fire bed. The hole can be closed off, partly or fully, to regulate the flow of air to the fire, by means of 2 vertical slabs of fireclay resting on the brickwork of the firemouth. Examples of this type of firemouth can be see on the bottle ovens at Middleport Pottery, Middleport. Compared with the firemouth with cast iron doors, this type of firemouth would have been cheaper to construct but perhaps a little more difficult to operate.

Vertical firemouth, vertical feed hole, no firedoors
Fireclay slabs missing
Middleport Pottery, Middleport
Photo: courtesy Jason Adams  Date July 2023

Brief explanation of the use of either firedoors or fireclay slabs
 to close the bottle oven firemouth.
from "Pottery Ovens, Fuels and Firing"
by Stanley R. Hind 1937

Vertical firemouth, vertical feed hole, no firedoors
Middleport Pottery, Middleport
Photo: Terry Woolliscroft collection  Date: July 2023

C. Horizontal, hob-mouth feed hole, with horizontal sliding fireclay slabs

This type can be found on some of the remaining bottle ovens in Stoke-on-Trent. Firemouths are built in the side of the oven, to create a wide hob or 'ledge'. A horizontal feed hole is built into the hob immediately above the firemouth and fire bed. Coal is baited (shovelled) onto the fire bed. The hole can be closed off  by means of  loose slabs of fireclay placed or slid over the feed hole.

Bottle oven with Hob Mouth
Falcon Pottery, Sturgess Street, Stoke
Photo taken as part of Bottle Oven Survey, 1976
Two ovens still remain on this site (2023)

Hob mouthed oven baiting
Fieldings Crown Devon Pottery, Stoke
Photo: Source unknown  Date: 1930s

Hob mouthed oven baiting
Jim Evans fireman at Spode, Stoke
Photo: Source unknown  Date: Unknown 

FLOOR FLUES 

In an updraught bottle oven, a system of flues, running under the floor, distribute  hot gases and heat from the firemouths to the centre of the firing chamber. According to Stanley Hind in his book - Pottery Ovens Fuels and Firing - the aim was to 'maintain all quarters of the oven in the same state of progress' and to 'to bring up the bottom heat with as little lag as possible behind the upper parts' so as to give a consistent 'fire'. 

In a downdraught bottle oven the flue system is more complicated since hot gases passing through the setting during firing needed to travel a more complex path so as to pass as much heat as possible to the products being fired. 

The design and layout of the flues varied according to the type of bottle oven - updraught or downdraught - and its overall size. Generally, flues were constructed as big as possible, depending on structural stability, to give as much air flow (heat distribution) as possible, and to make the job of controlling the oven by the fireman as straightforward as possible.

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

Bottle oven construction flue plan
From "Notes on the Manufacture of Earthenware"
by E A Sandeman, 1901

CHIMNEY ORNAMENTATION

The decorative ornamentation to the top of a bottle oven chimney was influenced by practicality, the builder's preference, skill and whim, and to its location.

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

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

Bottle oven chimney ornamentation
Photo: Source unknown

Bottle oven chimney ornamentation 
Burslem, Moorland Pottery muffle kiln 
Photo: Terry Woolliscroft Collection  Date: July 2019

Bottle oven chimney ornamentation
Photo taken from Normacot Road, towards Chelson Street
(was formerly Bagnall Street) 
New Chelsea Porcelain Co. In deference to St James Church, next door,
to the left, out of view, in Uttoxeter Road, Longton.
 The cross was created in white glazed bricks on the chimney stack.
Photo:  Terry Woolliscroft Collection   Date: 1970

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

Bottle oven chimney ornamentation 
Bottle ovens at Garfield Works, Uttoxeter Road, Longton
The 1927 and 1939 ovens decorated in white glazed bricks
Photo: Terry Woolliscroft Collection   Date: Late 1970s

NOTES on the MANUFACTURE OF EARTHENWARE 

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 & KILN BUILDERS of THE POTTERIES

F Brammer

30 Lorne Street, Burslem

Wengers Ltd.
Etruria, Stoke-on-Trent

Talbots
Hanley

H. Howlett and Sons
Bryanswood and Boundary Street, Hanley.
"Specialists as oven and kiln builders."

Mountford 
Kiln Builders

Alfred Moore
Longton

Leonard Salmons
Longton

Thomas Willet & Co

Burslem
Not a builder but a supplier to the trade. Iron Foundry. Known to manufacture bottle oven iron work: wicket surrounds, firemouth and door furniture, bonts.

"THE ERECTION OF OVENS AND KILNS" by Wengers Ltd.

Wengers Erection of Ovens and Kilns 1937

Download pdf here>

BUILDING THE 'CROWN' (DOMED ROOF) of the FIRING CHAMBER

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.”

BRICKS

WHAT TYPES of BRICKS WERE USED in OVEN and KILN CONSTRUCTION?

Two basic types of brick were used during the construction of a bottle oven.

Ordinary building bricks called 'common bricks' were used wherever little or no heat was present. So, for instance, commons were used during the building of the hovel or the stack of the oven. They were also been used for the outer wall of the firing chamber itself, away from the fierce heat of the fires. Common bricks provided sufficient strength in these areas. They were also very cheap to buy compared with heat resisting fireclay bricks. Common bricks were commonly available and local brickworks would have supplied these.

The more expensive, specialist, 'fireclay refractory bricks' were used wherever the oven was subject to intense heat. So the firemouths, glut arches and flues would be built with fireclay bricks. So too were the bags and the wall immediately above and surrounding the bags. Specialist brickworks having access to fireclay (found together with coal seams) were able to produce the specialist hard-wearing and heat resistant bricks.

COMMON BRICK MANUFACTURERS

Berry Hill Brickworks
Berry Hill, Stoke-on-Trent

Berry Hill Bricks
Advertisement 1957

Cobridge Brick and Marl Co. Ltd.
Cobridge

Apedale Heritage Centre, Newcastle-u-Lyme,
bricks collection
Date: Jan 2020

Fenton Collieries
Fenton, Stoke-on-Trent

Fenton Collieries Brick
Photo: unknown source  Date: unknown

Sneyd Brickworks
Nile Street, Burslem, Stoke-on-Trent

Advertisement Sneyd Brickworks Ltd
Nile St., Burslem

FIRECLAY BRICK MANUFACTURERS

D. Duddell Ltd.
Fenton, Stoke-on-Trent
In the Potteries a favourite supplier of fireclay bricks was the firm of  D. Duddell Ltd. Fenton.
http://www.thepotteries.org/brickworks/lane_end.htm


Sneyd Colliery Co. Ltd.
The Sneyd Colliery and Brickworks Company, Ltd.,
Nile Street, Burslem

Fireclay brick used in the construction of the enamel kiln
at Gladstone Pottery Museum Stoke-on-Trent.
Used on the doors to the kiln.
Makers mark impressed in the clay: SNEYD 

Harris and Pearson
South Staffordshire
http://www.harrisandpearson.info/index.html 


E J and J Pearson
Fire Brick Works, Stourbridge, Worcs.
Founded 1860
Manufacturer of firebricks and fireclay goods at the Delph Works, Brierley Hill, which was their main centre of operation. They also owned the Crown Works, Amblecote; and Tintam Abbey Mines and Works at Brierley Hill. The combined output of these three sites in 1903 was around three-quarters of a million firebricks per week. The company also produced speciality bricks and tiles used in the construction of pottery kilns, glass house pots, gas retorts, crucibles, linings of blast furnaces etc.(Courtesy: Graces Guide https://www.gracesguide.co.uk/E._J._and_J._Pearson)

Fireclay brick used in the construction of the enamel kiln
 at Gladstone Pottery museum, Stoke-on-Trent.
Used in the wall of the kiln.
Maker's mark impressed in the clay:
E J and J Pearson Ltd, Stourbridge
Photo: Terry Woolliscroft Collection  Date: July 2019

Berry Hill Brickworks Ltd
Berry Hill, Stoke-on-Trent

Berry Hill Brickworks
Advertisement 1960s

Hall Brothers 
(J. T. Hall Refractories)
Stourbridge.


Bonnybridge Silica and Fire Clay Co.,
Bonnybridge, (just north of Glasgow), Scotland
https://www.scottishbrickhistory.co.uk/bonnybridge-silica-and-fire-clay-co-bonnybridge/


John Stein
Castlecary Fireclay Works, Castlecary, Scotland
https://www.scottishbrickhistory.co.uk/john-gilchrist-stein-fire-bricks-of-great-importance/

Fireclay brick used in the construction of the enamel kiln
at Moorland Pottery, Burslem.
Used in the walls of the kiln.
Maker's mark THISTLE impressed in the clay. 
John Stein, Castlecary Fireclay Works, Castlecary
Photo: Terry Woolliscroft Collection  Date: July 2019
Information courtesy: Mark Cranston  www.scottishbrickhistory.co.uk

BRICK SHAPES

To enable the complex shaping of both the hovel and the firing chamber a number of specially shaped bricks were used.

Tapered bricks used in bottle oven construction
Gladstone Pottery Museum, Longton

Tapered and curved bricks used in bottle oven construction
Gladstone Pottery Museum, Longton

Bull nosed bricks used in bottle oven construction
Gladstone Pottery Museum, Longton

Special refractory bricks, branded 'Thistle'
Manufactured by the John Stein Company,
Castlecary Fireclay Works, Scotland.
Found in Burslem at the Moorland Pottery muffle kiln 
Photo: Terry Woolliscroft Collection  Date: July 2019
Information courtesy: Mark Cranston  www.scottishbrickhistory.co.uk

Some brick shapes

BRICKWORKS and TILERIES in THE POTTERIES

According to Mr. Mort Brandon (via Phil Jenkins) on Facebook, the figure for the number of brickworks in the Potteries in 1875-76  was 122.

The list below is courtesy http://www.thepotteries.org/brickworks/index.htm and shows 43.

1. Acres Wood
2. Adams, Tunstall
3. Apedale
4. Audley Brick & Pipe Co
5. N Barlow
6. Basford & Trent Vale Tileries
7. Basin Brick & Tile Co
8. Berry Hill Brickworks
9. Berry Hill Collieries
10. Bradwell Wood Tileries
11. Brownhills Tileries
12. Cannon Street Brickworks
13. Cobridge Brick and Marl Co Ltd
14. Cobridge Brick & Sanitary Pipe Co Ltd
15. Cobridge Collieries
16. Dalehall Brick & Tile Co
17. Eastwood Brickworks
18. Fenton Collieries
19. Fenton Tileries
20. W Ford
21. Robert Heath & Sons Ltd
22. J Hewitt & Son
23. Highfield Tileries
24. Lane End Works Ltd
25. William Lea
26. Lodge Tileries, Trent Vale
27. Metallic Tileries
28. Midland & Port Vale Tileries
29. Mow Cop Brick Co Ltd
30. J Noden & Co
31. North Staffordshire Brick & Tile Co Ltd
32. William Palmers
33. Plant & Hammersley
34. Rufus Brick & Tile Ltd
35. Sneyd Colliery Co Ltd
36. Stafford Coal & Iron Co
37. Tunstall Tileries
38. Walker
39. Watkin
40. Wheatly Brick & Tile Co
41. Wigley & Shirley
42. Wilkinson Brothers
43. C Wooldridge

SOME CONSTRUCTION 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. (Source: Mountford, kiln builder)