Clay was plentiful in Shropshire and was used for many products like tobacco pipes, as well as common bricks, tiles and pipes. The most famous product, however, is Coalport Porcelain which is still being made, albeit now in Staffordshire. An industry grew up in the area around Coalport and Benthall from the end of the 18th Century. As well as Coalport pottery, there were several other factories that are less well known. Anyone with a particular interest in the industry is recommended to visit the Coalport China Works of the Ironbridge Museum.
There are three main types of pottery :-
This is a vitreous ceramic ware made from non-refractory fire clay. It is hard enough to resist scratching by a steel point and is more opaque than porcelain. It is usually coloured grey or brown, because of impurities in the clay used for its manufacture, and is normally glazed. Maximum firing temperatures vary from 1100-1300°C. There are 6 types of stoneware :-
· Traditional - dense and inexpensive. It is opaque, can be of any colour and breaks with a conchoidal or stony fracture. Made from fine-grained clays which can used to shape very large pieces.
· Fine - made from more carefully selected, prepared and blended raw materials. It is used to produce tableware and art ware.
· Chemical - used in the chemical industry and elsewhere when resistance to chemical attack is needed. Purer raw materials are used than for other stoneware bodies.
· Thermal Shock Resistant – has materials added to enhance the thermal shock resistance.
· Electrical - was once used for electrical insulators but now replaced by electrical porcelain.
· Flintless - made from natural clay to which no flint, quartz or other form of free silica has been added
Porcelain (aka China)
This is a ceramic material made by heating a form of clay called kaolin to temperatures between 1,200-1,400°C. The strength and translucence of porcelain arises mainly from the formation of glass and the mineral mullite at those high temperatures. The name comes from the Italian word porcellana (cowrie shell) because of its resemblance to the translucent inner surface of the shell. Kaolin is only found commercially in Britain around St Austell in Cornwall, where it is still opencasted. The composition of porcelain varies and, as well as kaolin, it may have mixed in with it feldspar, ball clay, glass, bone ash, steatite, quartz, petuntse or alabaster. Porcelain does not need glazing to render it impermeable to liquid but most are still glazed for decorative purposes and to make them resistant to dirt and staining. It can be decorated under the glaze using pigments such as cobalt and copper or over the glaze using coloured enamels. Modern porcelain is usually fired at around 1,000°C and then sent for a second glaze-firing at a temperature of about 1,300°C or greater.
This is the general term for any pottery that is not stoneware or porcelain. It is fired at relatively low temperatures and vitrification does not take place, leaving it porous. It is not translucent and is normally relatively thick and very heavy. It is far easier to make, as a wide range of clays can be used, and it is much more tolerant of low and variable firing temperatures. Most modern craft and amateur pottery is earthenware. After firing, the body is porous and opaque and, depending on the raw material used, will be coloured from white to buff to red. It is less strong and more porous than stoneware but is less expensive and easier to work. Due to its higher porosity, it must usually be glazed in order to be waterproof. Modern earthenware is usually fired to temperatures between 1000-1150°C. For red earthenware, firing temperatures in the bisque kiln can greatly affect the color, ie firing at lower temperatures will produce a bright red colour and the hotter it is fired, the darker it becomes. When fired at a very high temperature, it becomes extremely weak and turns a dark black.
The raw materials for pottery can be classified as :-
· Kaolin - sometimes referred to as China clay because it was first used in China.
· Ball Clay - an extremely pliable, fine grained sedimentary clay, which may contain some organic matter. Small amounts can be added to porcelain to increase plasticity.
· Fire Clay - a clay having a slightly lower percentage of fluxes than kaolin but usually quite pliable. It is a highly heat resistant form of clay which can be combined with other clays to increase the firing temperature and may be used as an ingredient to make stoneware items.
· Stoneware Clay - suitable for creating stoneware. This clay has many of the characteristics of fire clay and ball clay, having a fine grain and being heat resistant.
· Common Red Clay & Shale Clay - have vegetable and ferric oxide impurities which make them useful for bricks but are generally unsatisfactory for pottery except under special conditions of a particular deposit.
· Bentonite - an extremely pliable clay which can be added in small quantities to other clay to increase the plasticity.
Pottery can be shaped by a range of methods :-
Hand Building - was the earliest forming method. Items are constructed by hand from coils of clay, combining flat slabs of clay, or pinching solid balls of clay or some combination of these. Parts of hand-built vessels are often joined together with the aid of slip, an aqueous suspension of clay and water. An item can be decorated before or after firing.
Potter's Wheel - used in a process called "throwing" (from the Old English word thrawan which means to twist or turn). A ball of clay is placed in the centre of a turntable, called the wheel-head, which the potter rotates with a stick, foot power or a variable-speed electric motor. During the process, the wheel rotates while the solid ball of soft clay is pressed, squeezed and pulled gently upwards and outwards into a hollow shape. The steps are :-
Centering - pressing the rough ball of clay downward and inward into perfect rotational symmetry.
Opening - making a centered hollow into the solid ball of clay.
Flooring - making the flat or rounded bottom inside the pot.
Throwing or Pulling - drawing up and shaping the walls to an even thickness.
Trimming or Turning - removing excess clay to refine the shape or to create a foot.
Considerable skill and experience are required to throw pots of an acceptable standard. In addition to the potter's hands, tools can be used such as paddles, anvils, ribs, knives, fluting tools and wires. Thrown pieces can be further modified by the attachment of handles, lids, feet and spouts.
Granulate Pressing - shaping pottery by pressing clay in a semi-dry and granulated condition into a mould. The clay is pressed into the mould by a porous die through which water is pumped at high pressure. The granulated clay is prepared by spray-drying to produce a fine and free-flowing material having a moisture content of between about 5-6%. Granulate pressing, also known as dust pressing, is widely used in the manufacture of ceramic tiles and plates.
Injection Moulding - suited to the mass production of complex-shaped articles. One advantage of the technique is that it allows the production of a cup, including the handle, in a single process and thereby eliminates the handle-fixing operation and produces a stronger bond between cup and handle. The feed to the mould die is a mix of approximately 50-60% clay in powder form, together with 40-50% organic additives composed of binders, lubricants and plasticisers.
Jiggering & Jolleying - carried out on the potter's wheel and allowing the time taken to be reduced. Jiggering is the operation of bringing a shaped tool into contact with an item under construction, the piece itself being set on a rotating plaster mould on the wheel. The jigger tool shapes one face while the mould shapes the other. It is only used in the production of flat wares, such as plates, but a similar operation, jolleying, is used in the production of hollow-wares such as cups. Jiggering and jolleying have been used in the production of pottery since at least the 18th Century. In large-scale factory production, jiggering and jolleying are usually automated, which allows the operations to be carried out by semi-skilled labour.
Roller-Head Machine - a machine for shaping items on a rotating mould, as in jiggering and jolleying, but with a rotary shaping tool. This is a shallow cone, having the same diameter as the item being formed and shaped to the desired form of the back of the article being made. Items may be shaped quickly using relatively unskilled labour. It is the most common method for producing flatware.
Pressure Casting –a mould is subjected to high external pressures. The high pressure leads to much faster production rates. It also allows a new casting cycle to be started immediately in the same mould, unlike plaster moulds which require lengthy drying times. Pressure casting was developed in the 1970s for the production of sanitary ware but more recently it has been applied to tableware.
RAM Pressing - used to shape items by pressing a lump of clay into a required shape between two porous moulding plates. After pressing, compressed air is blown through the porous mould plates to release the shaped item.
Slipcasting - a slip, made by mixing clay with water, is poured into a highly absorbent plaster mould. Water from the slip is absorbed into the mould, leaving a layer of clay covering its internal surfaces and taking its internal shape. Excess slip is poured out of the mould, which is then split open and the moulded item removed. Slipcasting is widely used in the production of sanitary ware and is also used for making smaller articles, such as intricately detailed figurines.
Clay ware takes on varying physical characteristics during the making of pottery :-
· Greenware refers to unfired objects. They are soft and can be easily deformed by handling.
· Leather-hard refers to an item that has been partially dried. It is very firm and only slightly pliable. Trimming and handle attachment often occurs at the leather-hard state.
· Bone-dry refers to an item when the moisture content is at or near 0%. It is now ready to be bisque fired.
· Bisque refers to an item after it is shaped to the desired form and fired in the kiln for the first time. Mineral components will undergo chemical changes that will change the colour of the clay.
· Glaze fired is the final stage. A glaze may be applied to the bisque form and the object can be decorated in several ways. After this the object is glazed fired, which causes the glaze material to melt, then adhere to the object. The glaze firing will also harden the body still more as chemical processes can continue to occur in the body.
A glaze is a layer of a vitreous substance which is fused to a ceramic object through firing. Glaze can serve to color, decorate, strengthen or waterproof an item. Ceramic glaze raw materials include silica, which will be the main glass former. Various metal oxides, such as sodium, potassium and calcium, act as a flux to lower the melting temperature. Aluminium, often derived from the clay itself, stiffens the molten glaze to prevent it from running off the item. The visual appearance of the fired glaze can be altered with colourants such as iron oxide, copper carbonate or cobalt carbonate and opacifiers such as tin oxide or zirconium oxide. The glaze can be applied by dusting a dry mixture over the surface of the item or by inserting salt or soda into the kiln at high temperatures. The latter process creates an atmosphere rich in sodium vapor that interacts with the aluminium and silica oxides in the item to form glass, producing what is known as salt glaze pottery. The most common method is to use a glaze in an aqueous suspension of various powdered minerals and metal oxides, which are applied by dipping items directly into the glaze. Other techniques include pouring the glaze over the item, spraying it on with an airbrush or applying it directly with a brush or other tool. To prevent the glazed article from sticking to the kiln during firing, either a small part of the item is left unglazed or supported on small refractory supports called kiln spurs which are removed and discarded after the firing. Small marks left by these spurs are sometimes visible on finished ware.
Decoration applied under the glaze on pottery is generally referred to as underglaze. Underglazes are applied to the surface of the pottery, which can be either greenware or bisque. A wet transparent glaze is applied over the decoration. The pigment fuses with the glaze and appears to be underneath a layer of clear glaze. Decoration applied on top of a layer of glaze is referred to as overglaze. Overglaze methods include applying one or more layers of glaze onto an item or by applying a non-glaze substance such as enamel or metals over the glaze. Overglaze colors are low-temperature glazes that give ceramics a more decorative, glassy look. An item is fired first, overglaze is then applied and it is fired again. Once the item is fired and comes out of the kiln, its texture becomes smoother because of the glaze.
Firing produces irreversible changes in the item and it is only after firing that it is termed as pottery. Firing pottery can be done using a variety of methods, with a kiln being the usual firing method. Both the maximum temperature and the duration of firing influence the final characteristics of the ceramic. Thus, the maximum temperature within a kiln is often held constant for a period of time. The atmosphere within a kiln during firing can also affect the appearance of the finished wares. An oxidising atmosphere, produced by allowing air to enter the kiln, can cause the oxidation of clays and glazes. A reducing atmosphere, produced by limiting the flow of air into the kiln, can strip oxygen from the surface of clays and glazes. This can affect the appearance of the items being fired and, for example, some glazes containing iron turn brown in an oxidising atmosphere but green in a reducing atmosphere. The atmosphere within a kiln can be adjusted to produce complex effects in glaze. Kilns may be heated by burning wood, coal and gas or by electricity. When used as a fuel, coal and wood can introduce smoke, soot and ash into the kiln which can affect the appearance of unprotected wares. For this reason, items fired in wood or coal-fired kilns are often placed in the kiln in saggars (circular lidded ceramic boxes) to protect them.
Modern kilns powered by gas or electricity are cleaner and more easily controlled than older wood or coal-fired kilns and often allow shorter firing times to be used.
Gazetteer of Sites
Atcham - Tern Bridge Roman Pottery (SJ55230917)
In 1949 large sherds of Roman pottery were found at a point on the left bank of the River Severn, 200ft upstream of its present junction with the River Tern. This is a point where the river is rapidly eroding its left bank. Excavations by A Houghton found kiln waste and a number of hearths and floors. It was concluded that the river had eroded away the actual kilns. Some of the pottery being manufactured at the site was very similar to items found at Wroxeter for which a local origin had been proposed. The greatest period of activity of the site was thought to have been from the early 4th Century onwards.
Benthall - Benthall Potteries (SJ66100200)
The pottery was founded in 1772 when John Thursfield built a new manufactory north of his existing Haybrook Pottery and worked the two in conjunction. His son John later entered the business and was joined by his brother-in-law William Pierce. Pierce & Co ran the Benthall Pottery until 1817-18. It was then taken by Samuel Roden & Co, who had the lease until 1823-4 when John Farnall became proprietor. Farnall still ran the works in 1837 and perhaps remained in charge until 1845 when W T Jones and Edwin Bathurst, lessees of the Haybrook Pottery, reunited the two concerns. They remained a single business, the works being known collectively as the Benthall Potteries, although in the early 1850s, when there were 31 employees at the Benthall Pottery, Jones and Bathurst may have divided the managerial responsibility with the latter running the Benthall concern.
The main products were then Rockingham-style ware and stoneware. Between 1862-1907 the Benthall Pottery Co was run by William Allen and thereafter, until the early 1920s, by his son W B Allen. In 1880 the traditional coarse red and yellow ware still sold readily in Wales. Allen, however, was beginning to promote the works as the Salopian Decorative Art Pottery Co. In 1882 its products included copies and adaptations of vessels from the ancient world, pots based on flower heads, and barbotine ware. By 1901 Allen's attempt to raise the character of the products had largely foundered and, apart from a few Greek and Hispano-style vessels, the manufacture was mainly coarse wares, lamp bases, and electrical engineering ceramics. In 1929 the company was re-formed as the Benthall & Ironbridge Pottery Co Ltd, which continued trading until the Second World War.
Benthall - Haybrook Pottery (SJ66300190)
The pottery was started about 1742 by John Thursfield. In 1772, he set up the nearby Benthall Pottery and the two sites were worked in conjunction until his death. By 1845 the Haybrook works were owned by W T Jones and Edwin Bathurst who then reunited the two concerns. They remained a single business, the works being known collectively as the Benthall Potteries, although in the early 1850s, when there were 31 employees at the Benthall Pottery, Jones and Bathurst may have divided the managerial responsibility with the former running the Haybrook concern.
The main products were then Rockingham-style ware and stoneware. In 1929 the company was re-formed as the Benthall & Ironbridge Pottery Co Ltd, which continued trading until the Second World War. This site ceased working around 1940 and the buildings were demolished by the 1980s. The site was subsequently destroyed by mining operations.
Broseley - Barrattshill Pottery (SJ66880198)
Excavation revealed brown lead-glazed wares, yellow slipwares and brown salt-glazed stonewares, all of the period 1700-1720. The quantity of material on the site, especially the bulky saggars, suggests that the two kilns were needed on the site. Site now occupied by Barrattshill Farm.
Broseley - Caughley China Works (SJ69200010)
The pottery was established in 1772 by Thomas Turner who used to work for the Worcester porcelain factory. The porcelain products were called Salopian Ware and were blue and white in colour. White porcelain was supplied to independent decorators. One distinction of the factory was its introduction of the willow pattern.
The original design dated 1779 was intended for a teapot and the best-known version was developed by Turner in the late 1780s. Blue Willow ware was produced by many subsequent factories, perhaps the most widespread of domestic designs. The Caughley works was bought by John Rose in 1799 and closed in 1814.
Broseley - Caughley Saggar Works (SO69069956)
A map of Caughley Estate drawn in 1780 by Thomas Bryan indicates "The Saggar Works" south-west of the main Caughley China Works, near Darley on the Dean Brook. A T-shaped building is shown, with two round bulges, possibly kilns, in the middle of one arm and at the end of the other. The works are in a small clearing in the woods, near to several small cottages. A second map drawn in 1795 shows that by this date the saggar works had been demolished. Nothing is shown on the 1883 OS map but excavations in 1987 located demolition rubble and fragmentary structural remains of the works (including walls and part of a quarry tile floor). Quantities of clinker, coal and ash and curved vitrified kiln bricks indicate permanent, circular coal fired kilns, whilst surrounding clay and coal workings provided raw materials. There was no evidence of any pottery manufacture on the site but some roof tiles may have been made.
Cleehill - Guller Pottery (SO58167576)
A pottery works was shown here on a map of 1827 and the the 1832 OS map but there was no trace by 1884.
Coalford - Coalford Pot Works (SJ6820290)
Working prior to 1882 and up to 1903 but closed by 1927. Making basic household ware.
Coalport - Coalport Porcelain Works (SJ69500240)
The pottery was established in 1795 by John Rose next to the Coalport Canal. He had previously worked at the Caughley China Works and had been making pottery himself in Jackfield since about 1780. He employed William Billingsley as chief painter and a Mr Walker as chemist, the latter introducing the well-known maroon glaze. During the 1830s, the factory started applying a light transfer printed blue outline, to guide the painters. This preserved some of the freedom of hand-painted decoration, while enabling an increased pace of production. This technique was widely adopted by other manufacturers during the 19th Century. John Rose died in 1841 and the works was continued under the former name of John Rose & Co by his nephew W F Rose and a William Pugh.
At the Great Exhibition in 1851, the company exhibited a Coalport table service commissioned by Queen Victoria as a gift to Tsar Nicholas I of Russia. William Pugh continued the production as sole proprietor from 1862 until his death in 1875, after which the company was put in receivership by his heirs. It was then reinstated as the Coalport China Co and an extensive export trade was started to the United States and Canada in the 1890s.
Production later moved across the canal to the buildings which now house the Coalport China Museum. In 1926 production moved to Staffordshire but the Coalport name was retained as a brand, the company subsequently becoming part of the Wedgwood group. The original factory is now a Youth Hostel, cafe, studios and shop.
Coalport - Swinney Mill Pottery (SJ70700180)
A pottery shown next to Swinney Mill in several paintings of the early 19th Century. It probably had a short life and only had one kiln, suggesting that it was producing coarse earthenware rather than anything more refined, which would normally need at least two kilns. Not shown on 1883 OS map, by which time it had probably been demolished.
Horsehay - Brandlee Pottery (SJ67800740)
Working in 1796 when new round-ware and dish-moulding houses were added to the works. Primarily made refactory clay vessels. It was still working in 1817 but had closed by 1843 when the site became Brandlee Brickworks.
Jackfield - Jackfield Pottery (SJ688029)
Pottery works in production during the 17th Century, possibly as early as 1634. The first documented operator is a Mr Glover who was succeeded by Richard Thursfield in 1713. The works were operated by the Thursfield family until 1772. From 1840 the works also produced tiles. Maps of 1845 and 1846 show the works to comprise three circular kilns and associated structures. The complex was demolished soon after 1871 to make way for the construction of Craven Dunhill Tileworks. Archaeological excavations have identified deposits of pottery waste and ash eroded from the river banks. These deposits comprise 18th Century waste - mainly white salt glazed wares, stonewares, comb decorated slipwares, saggers and kiln furniture. Forms include plates, bowls, jugs, tankards and tea and coffee pots. A wheel for grinding colours and materials was turned by the river.
Trefonen - Trefonen Pottery (SJ26162738)
A small pottery working prior to 1881 and up to 1890 but closed by 1901. The row of cottages, now known as Pottery Row, were the drying sheds where mugs, tiles, pipes and other articles were made. The kilns were situated on the site now occupied by the cottage gardens.
Walcot - Walcot Roman Pottery (SJ57911133)
Excavations in 1988 revealed a Romano-British settlement with pottery kiln waste, suggesting that there was a pottery in the vicinity. Occupation of the site was between the 2nd and 4th Centuries.