Types

No two alike!

No two bottle ovens or kilns were the same. Many, almost all of them, were built without architects drawings or plans. They were built 'by eye' based on the experience of the builder and the verbal requirements of the factory owner. Bottle oven builders were known to build an oven from scratch in 6 weeks.

Ovens and kilns all had very different 'characters'. Their firemen (the men responsible for firing the oven) had to learn how best to work with them. They had to control and cajole the way they were used, performed and fired.

But all ovens and kilns had one distinct and common feature, their bottle-shaped chimney stack, known as the hovel. It could be round or square at its base, or bulbous and shapely or straight sided and just as a simple cone. Hence the term bottle oven.

All potters' bottle ovens were described as intermittent since the firing process occurred periodically.  The process was not continuous. The oven was filled with pottery, then fired to temperatures as high as 1450ºC for some specific pottery recipes, then cooled and emptied. Then the process would start all over again. Busy potteries aimed to fire their ovens regularly, on a weekly basis, placing, firing and drawing on the same days every week. Large or higher temperature ovens took much longer.


What's the difference between a bottle oven and a bottle kiln  

The terms, bottle oven and bottle kiln, are often used interchangeably but this can sometimes get confusing. To most of us they mean the same thing - a complex brick-built, bottle-shaped structure for the firing of pottery or associated materials.

But there is a technical difference between the two.

Within the Staffordshire pottery industry, bottle oven usually meant the potters' oven used for the firing of biscuit or glost pottery. The oven had an open flame which passed from the firemouths directly into the firing chamber to envelop its contents. There were other types of ovens which included two-tier ovens (with an upper and lower chamber) and salt glaze ovens.

But a bottle kiln was designed and built differently. A potter's kiln was constructed in such a way that the products of combustion (flames, gases, smoke, sulphur fumes, ashes and dust) were not allowed to come into contact with the pottery being fired, being circulated through flues surrounding a enclosed firing chamber containing the pottery. Kilns of this type included enamel and hardening-on kilns, both used in the decorating process.

Other types of bottle kiln included calcining, frit or lime kilns which were used by material suppliers, for example for the calcining of flint or animal bone. Brick and tile kilns were also used.

Usage of the two terms varied from factory to factory, so it's difficult to be precise.


Bottle Oven and Kiln classification

In their heyday, the different types of bottle oven and kiln were not specifically listed or classified. People in the pottery industry knew exactly what they were!

But in 1921 Ernest Sandeman did describe the various types in his book 'Notes on the Manufacture of Earthenware' 1921.  And in February 1980 Alfred Clough (local pottery manufacturer and the man who fired a bottle oven in the Potteries for the last time, in 1978) described the difference between ovens and kilns during a public lecture.

The classification below is based on the work of Sandeman and Clough. It helps us to understand how they were built and how they were used.

Bottle ovens and bottle kilns can be classified by four main types. Within these four main types are additional variations.

There is also a fifth type, but, strictly speaking, it is not a bottle oven but a downdraught beehive brick kiln. It had no bottle-shaped chimney stack but is included here since it was also seen in the landscape of the Potteries.

In total, twelve variants are identified here.

1) UPDRAUGHT BOTTLE OVEN >
1.1 - updraught hovel oven
1.2 - updraught stack (or cone) oven
1.3 - updraught hob-mouthed oven
1.4 - updraught skeleton oven

2) DOWNDRAUGHT BOTTLE OVEN > 
2.1 - downdraught with separate chimney oven
2.2 - downdraught with integral stack, Wilkinson Patent type ("true downdraught") oven
2.3 - downdraught hovel oven

3) MUFFLE KILN >
3.1 - decorating (enamel) muffle kiln
3.2 - hardening-on muffle kiln
3.3 - fireclay muffle kiln

4) CALCINING KILN >

5) DOWNDRAUGHT BEEHIVE BRICK KILN >

Other Kilns >


1) UPDRAUGHT  BOTTLE  OVEN

The updraught was the simplest and most common type of bottle oven in the heyday of the pottery industry. There were four variants of updraught oven.

1.1 Updraught hovel oven

Sometimes known as 'oven and hovel' or in the Potteries dialect, 'ovn-n-ovl.'

The main feature of this type of bottle oven is that the freestanding hovel is completely separate from the freestanding firing chamber. The firing chamber stands inside the hovel. The distance between the two is sufficient to create a working space for the fireman and his oven men. The width of that space could be as narrow as a wheel barrow but was usually somewhat wider to allow the odd men to wield a shovel when lumping and baiting the oven. It also needed to be be wide enough to allow the fireman to use a poker or a trials rod - a long rod with a hooked end to extract firing trials from deep inside the firing chamber during firing.

Bottle oven, updraught hovel oven.
 Cross section and external view of an oven at Gladstone Pottery Museum, Longton.
The gap between the hovel and firing chamber was sufficiently wide
to give the fireman and his ovenmen work space.
Drawing and photo: Terry Woolliscroft Collection

The bottle oven consists of an inner firing chamber in which the pottery ware was placed and fired. The firing chamber had a domed roof called the crown. Iron bands, called bonts, were secured to the outside of firing chamber to support the structure during firing when it was subject to severe mechanical stress caused by temperature rise and fall.

The firing chamber is enclosed by a bottle shaped structure called the hovel. By law the hovel was required to be at least 60 feet tall. The hovel acts as a chimney, taking away the smoke and products of combustion. It also creates draught for the fires and protect the inside from the weather. The hovel also encloses the work space used by placers, oven men, odd men and the fireman. Sometimes the hovel became part of the factory workshops.

Entry to the inside of the firing chamber is through a doorway called the wicket. This doorway is tall enough for a placer with a full saggar balanced on his head to pass though easily. During firing the wicket is sealed with layered bricks,  daubed over with clay and silica sand. It is then known as the clammins.

Firemouths, situated around the outside of the firing chamber at ground level, are connected to brick flues and bags (small chimneys) on the inside. These carry the gases and intense heat from the coal, burning in the firemouths, to the ware inside. The flues converge at the well hole at centre of the domed floor of the chamber.

The intense heat rises up through the setting (containing the pottery ware in saggars) and then out through the top of the firing chamber and up its chimney stack, the hovel.

When used to fire biscuit earthenware pottery a bottle oven would reach temperatures of over 1200ºC.


1.2 Updraught stack (or cone) oven

This type of bottle oven has its hovel, the chimney stack, built directly onto the shoulder of the crown of the oven. This design was sometimes known as 'close coupled'.

Bottle oven, updraught stack (or cone) oven. 
Cross section.
The chimney was built directly onto the shoulder of the crown of the oven
Drawing: Terry Woolliscroft Collection


The updraught stack oven has no separate hovel. This is the form developed when a series or row of ovens were grouped together in a workshop, the chimney stacks rising through the roof of the building.

These ovens were solid and compact but they tended to be more difficult to repair since the chimney stack rose directly from the crown. (What does the owner do if a fault appears in the structure of the firing chamber? He might have had to knock the whole lot down, firing chamber and its chimney, and start all over.) These ovens also took longer to cool down.

The updraught skeleton oven looks very similar to the updraught stack oven but it was easier to maintain. See details below.

Bottle oven chimney stacks rising through the roof of the factory
Bottle oven, updraught stack (or cone) oven.
Bottle oven chimney stacks rising through the roof of the factory in
Sutherland Road, Longton
Photo: unknown source  Date: unknown

1.3 Updraught hob-mouthed oven

This was an older design of firing chamber, largely superseded in the late 19th and early 20th Centuries.  The firemouths of these ovens were built out from the firing chamber side walls projecting by up to 3 feet to create a hob or shelf above.  Coal was shovelled though a square hole constructed in the hob down onto the firebed below. The hole was covered, when baiting had finished, by a fireclay slab.

Fireman attending the hob-mouth of a bottle oven
Photo: Unknown source Date: probably 1950s

Bottle oven - hob mouthed View of baiting through the top of the hob
Bottle oven, updraught hob mouthed
View of baiting through the top of the hob
Photo: unknown source  Date: unknown

This method of baiting through the top of the hob was regarded as 'old fashioned' but it did have the distinct advantage that cold air was prevented from rushing into the firing chamber flues during baiting (unlike a firemouth with opening front doors which did allow cold air to be sucked into the interior).

A hob-mouthed oven could be an updraught stack type, or an updraught skeleton type. Two good examples, which still stand, (2019)  are in Stoke at the Falcon Pottery, Sturgess Street. The remains of a hob-mouthed oven can also be seen at the Spode factory, in Stoke.

Bottle ovens - hob-mouthed stack type Falcon Pottery, Sturgess Street, Stoke
Bottle ovens, updraught hob-mouthed stack type
Falcon Works, Sturgess Street, Stoke
Photo: unknown source  Date: unknown


Hob Mouth on an oven at  Falcon Pottery, Sturgess Street, Stoke
Hob mouth
Falcon Works, Sturgess Street, Stoke
Photos: Terry Woolliscroft Collection  Date: May 1976
Photo taken during The Bottle Oven Survey 1976 here>

Baiting the hob-mouthed oven
Photos: unknown source  Date: unknown

Baiting the hob-mouthed skeleton oven
Fieldings, Crown Devon Pottery, Stoke
Photo courtesy: The Sphere Magazine Date: 1930

1.4 Updraught skeleton oven

At first sight this looks very similar to an updraught stack oven. But it is constructed differently. The updraught skeleton oven tended to be preferred by potbank owners since it was less expensive to maintain. Work could be easily carried out on the firing chamber without affecting the hovel chimney.

In an updraught skeleton oven the hovel chimney is built from ground level, very close to but completely separate from, the firing chamber. The gap between the two structures is about the width of a building brick. The freestanding firing chamber could be maintained, or even knocked down and rebuilt, leaving the hovel chimney untouched.

Bottle oven, updraught skeleton oven.
Note the narrow gap (about a brick's width)
between the firing chamber and the hovel chimney.
Drawing: Terry Woolliscroft Collection

In order to allow the fireman and his ovenmen to attend to the firemouths during firing large gaps needed to be created in the brickwork around the base of the hovel chimney. The diagram below shows how open arches were built into the hovel chimney. The design and shape of these arches varied. The arches were directly in line with the firemouths. One of the arches led to the clammins.

Construction of the skeleton hovel chimney.
Open spaces in the hovel allowed the fireman and his oven men
to tend to the firemouths of the firing chamber contained inside.
Drawing: Terry Woolliscroft Collection

This variant, just like the updraught stack oven, could be built in a row in a workshop, the chimneys rising through the roof of the building. There is no working area between the hovel and the firing chamber.

This design of oven became very popular in the early 1900s because it seemed to combine all the best qualities of all the different types of updraught oven. It was simple in design and construction, relatively simple to operate, easy to build and repair and gave satisfactory results.

Interestingly, the design allowed the safe demolition and removal of the firing chamber whilst leaving the bottle shaped chimney behind. After the introduction of the Clean Air Act 1956 some pottery owners would have the firing chamber removed to create work or storage space. A few still standing in the Potteries are known as 'hovel only' for this reason eg. There is a fine example at Heron Cross Pottery.

SUMMARY - updraught bottle ovens

The simple graphic below shows the design and construction differences between stack, skeleton and hovel ovens.



2) DOWNDRAUGHT  BOTTLE  OVEN

This type of bottle oven is a more complex design than the simple updraught. It was developed in the early 1900s to make more efficient use of the coal fires.

Technically, the oven should be called 'updraught-downdraught' since the hot gasses pass through the setting of saggars not once but twice, theoretically extracting as much heat as possible from the burning coal fires. From the firemouths, the intensely hot gases flow upwards to the crown where they are deflected downwards through the setting of saggars containing pottery, and are then drawn out through the flues in the floor of the oven. The control of the flow of the hot gases was made by the use of dampers (robust adjustable flaps, over the crown, quarter and shoulder holes) which were opened and closed during the firing cycle. It was skilled work and the process was not written down since every oven was different.

Downdraught ovens were used mainly for biscuit firing, as it was considered that they were more economical in fuel, and that they could be worked to produce a more regular heat over all the oven.

There are three variants of downdraught oven.

2.1 Downdraught - with separate chimney

Some downdraught ovens were constructed with a chamber underneath the firing chamber bottom into which the downdraught flues ran. From this chamber a main flue was connected to a tall chimney stack (or shaft) standing separately from the oven. This chimney could be connected and used in common by several downdraught ovens. The main flue to this chimney was fitted with a regulator door that could be opened or closed, at will, to control the draught. The oven itself had its own bottle-shaped stack similar to an updraught oven.

This type of oven was lumped, kindled (lit), and baited in the same way as an updraught oven, but as it came up to a sufficient heat, the damper on the crown hole was closed and the regulator door in the flue to the outside chimney was opened. Heat was thus drawn, by draught, from the firemouths, up through the bags, and up to the oven crown. It was then deflected down through the setting of saggars containing pottery, into the bottom of the oven, into the exit or extract flues, and then away through the chamber to the outside chimney.

The "Clement Robey's Patent Oven" is an example of a downdraught. The patent also included the method for converting an existing updraught oven to a downdraught. 

There was a great deal of interest amongst Staffordshire potters in the 1880s for improving the performance of pottery ovens. Wilkinson and Minton also took out oven improvement patents. More here>  

It was claimed that this new oven design would save 35 to 50% in fuel, would produce a more uniform finished product, and would reduce saggar losses. The flat floor to the oven helped placing. Sampson Bridgwood Ltd. of Longton invested in Robey patent ovens in 1880 but by 1890 described the alterations as a 'failure'.


Advert for Robey's Patent Downdraught Oven
Source: Keates Directory of the Potteries and Newcastle 1879


2.2 Downdraught - with integral stack

These ovens were constructed with separate exit or extract flues below the oven base, rather than with a chamber as described in 2.1, above. This design avoided the expense of a separate outside chimney. These exit flues continued up the inside walls of the oven between the 'bags' eventually connecting to the oven's integral bottle-shaped chimney stack, above the crown. They were sometimes known as a "true downdraught."

After lumping, kindling, and first baiting, when the oven temperature was beginning to rise, hot gases passed from the firemouths, through the bags and up to the crown of the oven. Here the hot gases were deflected and directed downwards through the setting (between the saggars containing pottery) and down through the flues in the oven floor. Hot gases then passed to the flues in the inside walls to escape above the crown and up into the bottle-shaped chimney stack.


Bottle oven, downdraught, integral stack. Wilkinson Type.
The path of the hot gases from the firemouths was controlled by the use of dampers.
Drawing: Terry Woolliscroft Collection

The construction of this type of oven was complex and expensive.

The draught obtained by means of an oven with an integral stack may not have been sufficient, and if several ovens were to be built on the downdraught system it was probably cheaper to build an outside chimney to connect them all. The working results would be correspondingly better. 


Extract from a drawing of a downdraught biscuit bottle oven by Stanley Hind 1927
Bottle oven, downdraught, biscuit, integral stack. Wilkinson Patent.
Extract from a drawing by Stanley Hind   Date: 1937
Larger file for download here>

Description in 2.1 and 2.2 above are edited extracts from Chapter 13, Ovens and their Construction, from The Manufacture of Earthenware by Ernest Albert Sandeman, published 1921.


2.3 Downdraught hovel oven

The drawing below shows a downdraught bottle oven, with a separate hovel. The hovel acts as the chimney stack to create a draught while the oven is firing. It also protected the oven itself, and the placers and firemen employed to make it work.



MODEL OF DOWNDRAUGHT BOTTLE OVEN, WITH INTEGRAL STACK, WILKINSON TYPE

The photographs below show a unique model of a 'Wilkinson Type' downdraught bottle oven. It was donated to Gladstone Pottery Museum> in 1977 by Howletts, the renowned Potteries bottle oven builders.  The model is built to scale, exactly to the drawing above.


Gladstone Pottery Museum model downdraught bottle oven by Howlett 1977
Gladstone Pottery Museum model
Downdraught, stack type, bottle oven by Howlett 1977 




The oven has the following specification:
  • 11 x firemouths
  • 1 x crown damper
  • 7 x quarter dampers
  • 11 x updraught flues, situated between bags

Gladstone Pottery Museum model
Downdraught, stack type, bottle oven by Howlett 1977
Close up of wicket, firemouths, bonts


Gladstone Pottery Museum model
Downdraught bottle oven by Howlett 1977
Shows size of the model with viewing panel removed,
showing the crown of the oven.


Gladstone Pottery Museum model
Downdraught bottle oven by Howlett 1977
Shows the top of the crown, with crown damper, quarter dampers, and flues

Gladstone Pottery Museum model
Downdraught bottle oven by Howlett 1977
Looking down into the oven through the crown.
Shows bags, well hole, and unde-floor flues.

Click here> for a ten-frame Gif of the Bottle Oven Model on a turntable


3) MUFFLE  KILN

There were three types of potters' muffle kiln: decorating muffle (sometimes known as enamel muffle), hardening-on muffle, and fireclay muffle.

3.1 Decorating (enamel) Muffle Kiln

For the decorating enamel fire. Built in such a way that the flames and harmful gases of combustion were kept away from the pottery ware in the setting.

In this coal-fired kiln the flames did not directly enter the firing chamber as in downdraught and updraught ovens, but were led around the outside of the chamber by a series of flues. In this way no saggars were required but the delicate decorated colours of the decorated pottery were still protected. The firemouths were kept separate from the kiln chamber, sometimes outside.

A muffle kiln was a lot smaller than the other types of bottle oven and temperatures reached were lower at around 850ºC.

This temperature made the decorated colours permanent (without firing, the colours would easily rub or wash off) and did not need the higher temperatures required biscuit and glost.

Muffle kiln, for firing decorated pottery
Cross section and external view of the unique kiln at Gladstone Pottery Museum, Longton
Drawing and photo: Terry Woolliscroft Collection

Inside the muffle kiln chamber at Gladstone Pottery Museum and outside a muffle kiln in Longton
On the left: inside the muffle kiln chamber, on display at Gladstone Pottery Museum 2014
On the right: the exterior of a muffle kiln showing four firemouths.
Market St., Longton.
Photo: unknown source  Date: Unknown

Muffle decorating or enamel kiln
Huge, five-mouthed kiln. Fireman baiting.
Photo: unknown source  Date: unknown 

Bottle oven, muffle kiln, Furnivals, Elder Road, Cobridge
Charlie Boardman emptying the ash pit after a firing.
Photo: Courtesy of  Jenny Ward  Date: 1930s


Muffle kiln cross section

3.2 Hardening-on muffle kiln

Biscuit ware which has been decorated with an underglaze print or with hand painted pattern sometimes needs to be 'hardened on' so that the decoration won't smudge during the glaze dipping process. The hardening-on fire is at a relatively low temperature of around 700ºC  and ensures that the applied colour is not disturbed during dipping and that the oils in the colour are are evaporated.

The hardening-on muffle kiln was usually smaller than an decorating muffle kiln. Updraught

Bottle oven - muffle hardening-on kiln Oven interior Spode 1900 - 1920
Muffle hardening-on kiln  - interior.
Spode factory, Stoke
Photo: source unknown  Date: 1900 - 1920


Extract from an article about Enamel and Hardening-on Kilns  1927



download pdf here>


3.3 Fireclay muffle kiln

Fireclay products, for use in bathrooms and kitchens, are 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 pottery was fired in a muffle kiln.  Here the product was stacked in a huge box-like chamber which was kept sealed and away from the flames, smoke and other products of combustion of the burning coal.

Muffle oven firemouths Twyfords Stoke fireclay factory 1929  v1
Muffle kiln firemouths
Twyfords, Stoke fireclay factory Date: 1929  

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


4) CALCINING  KILN

A calcining kiln was not used to fire pottery ware.  Its purpose was to 'roast' materials, such as flint or animal bone, before they were crushed and ground and then used in the pottery body recipe. The kiln 'fired' the materials to very high temperature (above 1000ºC) to make them friable and easily crushed to a fine powder.

When they are in their raw state, flint and animal bones are impossible to crush as they are far too hard. Calcination changes the nature of these materials to such an extent as to make them suitable for easy crushing and grinding/milling to a fine powder suitable for adding the pottery body.

Calcining kilns for flint or bone were similar in construction. The kiln could consist of one or two firing chambers. If the kiln had two chambers, side by side, a single chimney (hovel) usually served both. The hovel built above created draught to aid combustion.

Flint calcining kiln - cross section
Drawing and Photo: Terry Woolliscroft Collection


Filling the calcining kiln was a skilled job. The bowl of the kiln was filled with the flint pebbles or raw bones, layering  fuel with the material to be calcined.

For both flint and bone, the calcined product was allowed to cool before being withdrawn manually through draw holes at the bottom of the firing chamber. Around 10 hours would typically be required for cooling. The whole process would take just over 24 hours.


FLINT CALCINING 
Flint is a major constituent of pottery bodies such as earthenware, sanitary earthenware, and wall tiles. Flint is a refractory material used to provide silica in the body. It is also used in glazes. It increases firing temperature and craze resistance but reduces plasticity and shrinkage. In 1950 around 2000 tons of flint were calcined weekly in the Potteries to meet the requirements of these sections of the industry.

Raw (uncalcined) flint pebbles -  each about 4" diameter
Photo: Terry Woolliscroft Collection  Date: 1980

Flint occurs naturally as hard, black/grey pebbles within cretaceous chalk beds. When calcined above 1000ºC crystalline water is driven off, shattering the pebbles and leaving them softer, lighter and whiter.

Flint was traditionally calcined by a method which, although thought to be economical it wasn't, and was acknowledged to be crude and not susceptible to close control.

Alternate layers of flint (between 5 and 6 tons in total) and coal, usually slack, (about 12 cwts) ) were charged into a funnel-shaped firing chamber, with a hovel above. The charge rested on 2.5 cwts of lump coal in the grate at the bottom of the chamber. This was then ignited with paraffin and the kiln allowed to burn itself out without further attention.

Flint calcining kiln 
Still standing (2019) in Hanley.  Former Johnson Bros., Trent Works.
Kiln is charged and ready for firing to calcine flint pebbles 
Terry Woolliscroft Collection   Date: July 1975

The time taken to calcine flint would depend on the type of flint, the quality of the fuel and the climatic conditions, but would take 8 to 16 hours. Bone (see below) would be quicker.

The calcined charge was screened in order to separate the coal ash, or simply "forked," the flint fines being discarded with the ash. After milling to a fine powder, this flint is added to the pottery body, according to a recipe.

Flint calcining kilns
Furlong Mills, Burslem
Photo courtesy: Andy Perkin, Potteries Heritage Society
Date: July 2019

BONE CALCINING
This is a component of a particular type of pottery which is known as Bone China. Calcined animal bone, usually cattle bones, preferably the shin bones of oxen, (honestly!) are used.

Cattle bones, from the butcher, unboiled
Awaiting calcining be for use in the Bone China pottery formula
Possibly Minton Date: c1900

The Spode company, under Spode I and Spode II, is credited by potters, collectors, researchers and other experts with having perfected the bone china formula before 1800.  1799 is the most likely date but it could perhaps be even a little earlier from circumstantial evidence.  https://spodehistory.blogspot.com/p/bone-china.html

About 50% of the bone china body formula (or recipe|) consists of this calcined animal bone. The remaining 50% being largely made up of China Clay and Cornish Stone. It is the bone which gives bone china its brilliant whiteness, strength and translucency.

Jesse Shirley, Etruria bone mill
Calcining kiln, centre right
Terry Woolliscroft Collection  Date: 2018

Bones are calcined at about 1150ºC to ensure all animal matter and other contaminants are burned away to render the calcium phosphate inert. Bone could be calcined with coal or wood as the fuel, although wood, if available, was preferred in order to reduce the possibility of iron in the coal contaminating the batch. Bones would be layered with the fuel, as in flint calcination. Because of its organic nature bone required little fuel once combustion had commenced.

After calcination bone ash can be ground to a fine powder and added to the bone china pottery body.





Calcining kilns Dalehall Mills Ltd., Adkins Street, Cobridge, Stoke-on-Trent photo D. Morris c1975
Calcining kilns
Dalehall Mills Ltd., Adkins Street, Cobridge, Stoke-on-Trent
Photo:  D. Morris   Date: c1975  Now demolished
Courtesy of Staffordshire Past Track here>

It is recorded that in 1838 bones were being purchased for use in a pottery company's bone china formula at a cost of "£6 per ton." The company said that they could take "one ton a fortnight" and insisted with the supplier that the bones should "be unboil'd fresh meat bones, no horse bones." The company insisted that "boiled bones were no use at all."


OTHERS
Other types of kiln included frit and lime kilns which were used by material suppliers. (More details to come)


5) DOWNDRAUGHT BEEHIVE BRICK KILN

Strictly speaking, this is not a bottle oven or bottle kiln since it has no characteristic bottle-shaped chimney stack. But it is included here since it too could be found in the landscape of the Potteries. No more remain.

The kiln had a domed roof and a perforated floor under which ran flues leading to the separate chimney stack. The circular or 'beehive' kiln had a capacity of about 12,000 bricks. Coal was lit and burned fiercely inside the eight firemouths around the outside of the oven. Hot gases were directed upward from mouths through bags (small chimneys inside the kiln itself) and then downwards from the underside of the dome and through the stacked bricks being fired into the under-floor flues, pulled by the draught from the chimney.


Cross section of a beehive type downdraught kiln
Image: source unknown


The firing cycle took around two weeks: two days for setting, three days for the water smoking period to drive off any moisture left in the bricks or tiles, two days for firing to full temperature, one day soak at full heat, then another three or four days to cool down and a further day to draw.

Beehive Brick and Tile kiln
Wheatly & Co Ltd, Trent Vale, Stoke-on-Trent
Photo: source unknown  Date: mid 1950s

Beehive Brick and Tile kiln A worker on top of pottery kiln in the yard  of Wheatly Brick & Tile Co Photo: source unknown  Date: mid 1950s
Beehive Brick and Tile kiln
A worker on top of pottery kiln in the yard
 of Wheatly Brick & Tile Co
Photo: source unknown  Date: mid 1950s

Beehive Brick and Tile kiln  Wheatly & Co Ltd, Trent Vale, Stoke-on-Trent   Baiting the hob mouthed oven with coal
Beehive Brick and Tile kiln
Wheatly & Co Ltd, Trent Vale, Stoke-on-Trent
Baiting the hob-mouthed oven with coal
Photo: Source unknown  Date: mid 1950s


Beehive Brick and Tile kilns  Knutton Tileries Photo: source unknown  Date: 1930s
Beehive Brick and Tile kilns. At least 22 can be seen here
 Knutton Tileries
Photo: source unknown  Date: 1930s

Fireclay Hole and Works, Cobridge, Stoke-on-Trent
Photo: Source unknown  Date: unknown

Tunstall. Downdraught beehive kiln.
Note separate chimney on right.
Daniel Platt & Sons, brick & tile manufacturers.
The Perry Family firing the kiln.
Source: unknown  Date: some time before 1935

Demolition of a Beehive Kiln

Here is an amazing video, on YouTube, of the demolition of a beehive kiln. Watch it to the end. I guarantee you will never forget it.




Description of firing a downdraught beehive kiln by Alan Hopwood, May 2016

The usual downdraught kiln was a 'beehive' shape with 10 fire mouths and a free-standing chimney, a few yards away. Then there were a series of flues going underground from the beehive to the chimney. At the bottom of the chimney was a big firehole.

This type of kiln was quite devilish to get going. A good fire was made up in the chimney so as to get a good draught through the flues from the beehive itself. Then you lit the fires round the beehive but as I said before it was quite sluggish at first. All the heat in this case was collected in the dome and was then drawn down through whatever wares were being fired, through the flues and across the yard to the free standing chimney.

I wouldn't like to guess what the temperatures were in these kilns but when one looked through the spyholes the light inside was more silver or even electric blue, instead of gold to white as in an updraught kiln.



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