Technical Guide

A brief simplified guide to terms you are likely to encounter in your quest for quality ceramics

Acid etching;- the treatment of glass with hydrofluric acid resulting in a matt or frosted finish.

Acid gilding;- etching on the glaze through a wax with acid, gold is then applied and burnished, the bright raised areas contrast with the sunken matt areas.

Agate ware;- type of pottery resembling agate as a result of partil blending of different coloured clays.

Art Deco period;- 1920 to 1940 took advantage of new materials and techniques to advance design and establish new luxury brands. Strong geometric lines, streamlined shapes and stylized decoration, such as chevrons and sunbursts. Strong bright or contrasting colours encouraged especially orange and reds. Clarice Cliff, Poole, Susie Cooper, Myott, Carlton and Wedgwood all produced Art Deco ceramics.

Art Nouveau period;- 1890 to 1914 inspired by the Rococo style uses flowing asymmetrical lines and a keen desire to reflect natural fauna and suggest fluid curvaceous movement. Often feminine in character potraying women with long flowing hair and billowing robes. Iridescent glass and semi precious stones popular in designs.

Arts and Crafts period;- 1860 to 1920 (related to the Aesthetic movement) It was a deliberate movement to bring back hand crafted goods as an alternative to mass produced goods resulting from the industrial revolution. Ornamental decoration was sparse to show off the natural beauty of the raw materials. Designers used traditional craft based methods to make simple functional pieces. Ault, Doulton, Martin Brothers, Ruskin and Moorcroft all produced Arts and Crafts ceramics.

Backstamp;- mark applied to the base of ceramics giving details of manufacturer. There can be several marks on the base of china items, impressed and or printed. They can inform you of the design, the age of the item, the potter, the artist, the retailer and even if it was a 1st or 2nd quality item.

Baroque period;- 1620 to 1720 porcelain not yet manufactured in Britain, most porcelain is blue and white tea and dinner ware from china at this time. Decoration was heavilly influenced by Italy and was generally very heavy and formal.

Bas-relief;- sculptural relief in which the projection from the body is slight and no part of the item is undercut.

Bat printing;- Images produced by dots of varying depth and closeness punched into a copper plate, covered in oil, surfaceoil removed but retained in the dots. A 'bat' (a thin pliable slab of glue or gelatine) was then used to transfer the dotted image onto the ready fired glaze of the china. A colourpigment could then be dusted on prior to 2nd firing.

Biscuit/Bisque;- white unglazed porcelain mostly used in the production of figures and groups of figures.

Black basalt;- an earthenware that is naturally black in colour post firing. Wedgwood is reknowned for its own black basalt which being produced from a very fine mix is extremely hard it was also usually given a surface polish by Wedgwood to make it more attractive than other black basalt wares.

Body;- the composite materials used to make each particular type of ceramic ware.

Bone china/Fine china;- consists of between 30 to 45% bone ash, usually cow bones, it is normally fired at a maximum temperature of 1220C. Bone chinas properties allow it to be fired twice in the kiln. The 1st firing results in shrinkage of the wares and the 2nd firing allows the glaze to unite with the ware. It is generally thinner, lighter, more translucent, and less likely to chip than porcelain. It is generally a warm off white colour.

Brownware;- salt glazed  brown stoneware, prevalent in Nottingham and Derby, includes a lot of bargeware.

Cachepot;- ornamental container for flower pots, a small form of jardiniere

Calcine;- to heat to a temperature that renders a substance easier to crush.

Caneware;- an unglazed light brown, tan or cane coloured stoneware.

Ceramic;- an object made of clay or other inorganic, non metallic material that has been shaped then made permanently hard by heating to over 1000C.

China;- a hard white translucent ceramic made by firing a pure clay then glazing it with coloured fusible materials.

Chinoiserie;- generic term for Chinese ornamental  motifs.

Chintzware;- items decorated all over with a floral pattern, usually dense.

Clobbering;- overpainting in enamels on previously decorated porcelain.

Cloisonne;- enamel decoration fired into compartments formed by metal wires.

Comport;- a flat plate on a pedestal always suitable for food use.

Compote;- another name for a  comport especially when it includes a lid or dome.

Console bowl;- a bowl designed as a centre piece for the dining table, to display fruit or flowers, popular in the UK in the 1920's to the 1950's should be accompanied with a matching pair or set of candlesticks.

Crackle glaze;- a deliberate cracked effect achieved by firing at a very precise temperature.

Cranberry glass or gold ruby glass;- red glass made by adding gold salts or colloidal gold to molten glass.

Crazing;- minute cracks in the glaze caused by the glaze shrinkage differing from the body shrinkage during cooling.

Creamware;- a salt glazed stoneware that is made from white clays and calcined flint. It is fired at a low 800C and glazed with lead, as the name suggests the end product is a basic cream colour as the lead glaze is transparent.

Crystal, lead or flint glass;- normal glass with the addition of lead or metal oxides, resulting in more transparent, highly refractive, finer yet stronger and heavier glassware. 

Cut glass;- glass decorated by making many deep cuts into the object

Delftware;- a coloured tin glazed earthenware usually dark blue and white.

Dipped wares;- items are dipped in a vat of coloured slip during decoration resulting in them looking like more expensive veined marble.

Early Neoclassical period;-  1760 to 1800 less exuberant style of decoration based on classical antiquities. Ancient Greek and Roman influences. Shapes in favour were rectilinear, fluted columns, Vitruvian scrolls/waves and garlands very prominent. Urns with decorative finials prevalent. Worcester, Derby, Bristol and New Hall potteries were at their peak. Plymouth, Longton Hall, Bow, Chelsea and Bristol factories had all come and gone. Lowestoft, Caughley, Coalport and Pinxton factories were all established.

Earthenware;- dates from the stoneage, a broad term for wares made of baked clay inclusive of Delft, Fayence, Stoneware, Terracota etc. The softest form of pottery fired at the lowest heat 1000-1200C it absorbs water and is porous. It was covered in a vitreous solution and refired to waterproof it.

Eggshell porcelain;- a type of slip cast razor thin porcelain.

Enamel;- a colouring pigment, usually on a lead base, fired to the glaze for decorating in a low temperature kiln 750 to 850C.

Engraved glass;- decoration of detailed design formed by removing thin sections of glass from the object.

Famille rose;- a colour pallete used on Chinese and Chinese style porcelain which includes a dominant opaque pink.

Famille verte;- a clour pallete used on Chinese and Chinese style porcelain with a dominant bright apple green.

Fayence/Faience;- a broad term for artistic tin 

glazed pottery usually highly decorated in colours includes Delft and Majolica.

Fettling;- removal of seams or casting marks on a vessel  prior to initial firing.

Finial;- an ornament finishing off the apex of lids.

Flambe;- a glaze made from copper, usually deep crimson, flecked with blue or purple, often faintly crackled.

Flashed glass;- produced by dipping clear glass into coloured glass and heating so that the layers then bond as they cool.

Fluting;- a set of regular grooves on the surface of wares.

Frit;- a mix of soluable and fusible alkaline salts of soda and potash processed to form a type of finely ground glass.

Fritted;- turning powdered materials into a porous mass by heating without adding a liquid.

Frog glass;- a decorative holed glass item placed in the tops of bowls or vases to seperate and hold flower stems.

Gadrooning;- decorative edging consiting of a series of convex, vertical or spiralling curves.

Gilding;- the application of leaf or liquid gold for decoration.

Glass;- a hard brittle ceramic, usually translucent, made by fusing sand with soda and lime and cooling rapidly.

Glaze;- an impervious layer or coating of a vitreous substance which has been fused to a pottery body through firing.

Green glaze wares;- earthenware with moulded decoration accentuated by being flooded with a green tinted glaze.

Green ware;- unfired pottery.

Ground laying;- applying a uniform colour ground to glazed porcelain. Usually achieved by applying a thin coat of oil and dusting it with the coloured powder.

Handblown glass;- glass produced by blowing a molten glass bubble into a mould. Can be identified by pontil marks to the base.

Hardening on;- low firing wares to fasten printed or painted underglaze colours to the biscuit before applying and firing the glaze, it helps retain the fine detail of decoration during glazing.

Hard paste china;- composed only of natural elements, unglazed parts of this china will not scratch or cut easilly and will file any fingernail that attempts to scratch it. Damage results in a curved surface at the break.

Hyalith and Lithyalin glass;- both these types of glass use a special mix of metal oxides resulting in an opaque black or dark red colour. In addition the Lithyalin glass surface was treated with metal oxides to produce a veined or mabled effect.

Intaglio carving;- type of carving where the forms are sunken into rather than proud of the surface.

Imari ware;- a generic Western term for Arita ware, (Japanese export porcelain originally shipped to the UK from the Japanese port of Imari.) It now applies to any china covered in colourful, bold patterns in underglaze blue, red and green enamel and gilding. Often overglazed with further colours. The overglaze styles of Kakiemon and Kutani are often included under the generic Imari ware group.

Impermeable/Impervious;- not allowing fluids to pass through. 

Impressed mark;- one that is stamped into the body of the ware while it is still soft.

Incised mark;- one that is drawn free hand into the body of the ware while it is still soft.

Iridescent;- showing luminous colours that appear to change when seen from different angles.

Ironstone;- a particularly hard, heavy and durable earthenware patented by CJ MAson in 1813.

Jasper dip;- Jasper ware that is only coloured externally by dipping, the interior remaining white/uncoloured.

Jasper ware;- a fine compact stoneware stained by various metallic oxides to delicate and permanent colours, usually blue. Normally stained throughout its mass.

Jewelled decoration;- the use of opaque or translucent drops of enamel, sometimes over gilt or silver foil, on top of the glaze to simulate inset precious stones.

Kaolin;- (china clay) a type of fine white granite clay used to make hard paste porcelain.

Kiln;- an oven designed to produce extreme heat.

Late Neoclassical period;- 1789 to 1815 in terms of the French Napoleonic influence on architecture and interior design. Also known as the Regency period in Britain (specifically 1811 to 1820 but more generally 1795 to 1837). Military influence resulting in laurel wreaths, medallions, eagles, lions, tripods also Egyptian imagery. Known as the Empire period in most of Europe. Lowestoft, Pinxton and Caughley potteries closed. Derby, Worcester and Coalport all continued strongly and were joined by Spode. Nantgarw, Swansea and Rockingham factories all opened and closed in this period.

Lithophane;- a porcelainous picture, the pattern produced by moulding so that, by transmitted light, the thinner parts show light and the thicker sections show dark. Occassionally overpainted to give greater contrast and effect. Invented in 1827.

Lustre decoration;- the application of metal pigments such as silver or copper to the glaze before reduction firing. It leaves a fine metallic film on the glaze giving the ware an iridescent appearance. Copper leaves a brown tone, Silver yellow, gold pink and platinum a silver tone.

Luting;- the use of watered down clay to assemble parts of a ware such as spouts or handles to a thrown or moulded form.

Majolica;- highly decorative glazed pottery, the earthenware body was covered with an opaque tin enamel glaze to imitate the early Italian Maiolica ware. Introduced by Leon Arnoux, Minton's art director in 1850.

Marbling;- a decorative effect produced by working together coloured slips in the same manner as marbled paper. Used mostly on creamwares 1780 to 1820.

Mocha;- decoration used on utilitarian earthenwares from the end of the 18th Century. A sponge or branch/tree like effect on the ware produced by the chemical reaction of an acid colourant on an alkaline slip.

Modernism period;- 1900 to 1950  the movement to make new functional designs sculptoral, organic and attractive in their own right, without unneccessary adornment/decoration.

Mosaic;- bits of ceramics similar in size and shape grouted together to form a picture or decoration.

Moulded glass;- the injection and or pressing of molten glass into a mould by machine, can be idientified by its seams.

Nappy;- a shallow and open topped small serving dish, rimless and flat bottomed, often with handle or handles.

On glaze;- any decoration painted in enamels or transfer printed on top of a fired glaze.

Opacity/Opaque;- lacking translucence/transparency.

Opaline glass;- coloured lightly translucent glass formed by adding ground calcified bones to the glass ingredients.

Over glaze mark;- marks stamped, printed or painted on the outside of the glaze.

Parian china;- slip cast porcelain that looks like the white marble quarried on the Greek island of Paros. Wedgwood calls its own Parian ware, Carrara ware. Before either of these terms it was all called Statuary porcelain.

Patch mark;- small circular blemishes on the base of wares, resulting from them being stood on small temporary clay pads during the firing of the glaze, to prevent the ware sticking to the saggar/sagger.

Pate sur pate;- porcelain decorated with layers of contrasting colour slip, usually white, upon a coloured unfired body, providing a thick enough clay to allow modeling as a bas relief.

Pearl ware;- another compact type of white earthenware introduced by Wedgwood  around 1779.

Pietra dura or Parchin kari;- inlaid marble or polished stones, sliced and cut in to different shapes, interlocked with grooves on the underside and secured in a frame. Differs from mosaics in that there is no grouting and no gaps between the bits of marble or stone.

Pontil;- is a solid metal rod that is tipped with a wad of hot glass and applied to the base of a vessel to hold it during manufacture. It usually leaves a scar on the base of the item held which is often polished out. The scar is also referred to as a pontil.

Porcelain;- fine china that rings when tapped with your finger, translucent when held to the light, it doesn't contain any bone ash. It is heavier than bone china and more brittle, it is normally fired at 1454C. It is generally a bright clean white colour.

Potash, fern or forest glass;- ashes of wood or bracken mixed with the sand pre heating resulting in a high % of potassium making the glass more durable and green in colour.

Pottery;- a fired ceramic ware that contains coloured clay when formed, opaque. There are 4 main types of pottery, Porcelain, Stoneware, Earthenware and Bone china. The 4 types are determined principaly by the type of clay used and the temperature that the articles are fired at.

Pounced;- a type of stencilling using powdered charcoal and a thin holed paper or metal sheet providing guiding outlines for the painter.

Press moulding;- the process of pressing the plastic clay into the sections of a mould. The sections  are then cast and luted together.

Print and enamel;- decoration which has been hand coloured on a printed outline.

Queen's ware;- a fine cream coloured earthenware, developed from creamware by Wedgwood in 1767 and named after Queen Charlotte who ordered lots of it.

Redware;- stoneware generally unglazed and often decorated with applied motifs in relief.

Reeded moulding;- decoration composed of convex columns.

Refratory;- ceramics that can endure high firing temperatures without deforming.

Registered designs;- from 1842 a ceramic form of decoration could be patented giving the owner 3 years protection against anyone copying the design. From 1842 to 1884 this registration mark was in the shape of a diamond panel stamped on the wares base. Since 1884 it is in the form of "RdNo" followed by a unique number listed under Registered Designs.

Relief decoration;- decoration that stands proud of the surface of the item, usually described by its depth as high or low relief

Reticulated;- a pattern of pierced work forming a net like design on the wares exterior.

Rococo period;- 1720 to 1760 an assymetrical, curvaceous style of decoration adopted, usually involving scrollwork, foliage, rockwork and shells. Birds and flowers were very popular decoration and chinoiserie, latticework, gilding and enamelling were all popular. Big French influence with a delicate symmetry and repeating patterns. Bow and Longton Hall potteries were at their peak. Chelsea, Bristol, Worcester, Lowestoft and Derby were also established pre 1760.

Saggar/sagger;- the refractory fire clay container that the wares are put in prior to loading in the oven/kiln. The saggar prevents the flames coming in direct contact with the wares.

Salt glazing;- throwing salt into the kiln when it is at its hottest, causes the salt to react with the silica in the clay, creating a thin glaze that has a texture like orange peel.

Sang de boeuf;- a brilliant red ceramic glaze developed in China.

Scratch blue;- the decoration of salt glze wares by making incised lines on the ware and then accentuating them by rubbing colouring matter into the design.

Sgraffiato;- the design is incised through a contrasting slip or glaze, exposing the colour of the underlying body.

Silk screen;- a transfer, printed with solid colours and/or gold, through a fine mesh stencil.

Slip casting;- the process of pouring watered down clay, (known as slip), into moulds, producing a thin cast which is formed on the inside wall of the mould. The wares produced are much lighter & thinner than those produced by press moulding.

Slipware;- a type of red bodied earthenware decorated with slip in contrasting colours.

Soda glass;- ashes of burnt seaweed mixed with the sand pre heating resulting in a high % of sodium carbonate making the glass lightly coloured and malleable.

Soft paste china;- various materials combined to form a transparent cement which is 1st heated and fritted, then mixed with other materials such as white clay to give opacity to the body. Soft paste china is easilly scratched with a pen knife or finger nail. Damage results in a granular fracture.

Sponged decoration;- decoration applied to the ware by taking pieces of shaped sponge, dipping them in a single colour and dabbing the sponge randomly over the ware, originated in and favoured by the Scottish potteries.

Sprigging;- the application of separately moulded decoration to the surface of wares prior to firing.

Stained glass;- achieved by taking a clear object and either dipping it in cool metal oxide, or painting it on, and then heating the item at a low temperature to fix the colour.

Steam hole;- the name given to the small hole on the lids of tea and coffee pots. The purpose was to let air in to displace the drink rather than to let the steam out.

Stilt or Spur marks;- small blemishes found on the outside of wares resulting from the small stilts or other items used to keep the wares free from each other and the base of the saggar.

Stippling;- decorative designs made by applying dots of colour with the point of a brush.

Stoneware;- hard impermeable glazed Earthenware, opaque, it is the densest pottery and is generally a grey material turning brown in the kiln. Stoneware is often salt glazed Wedgwood basalt and Jasper ware are good examples of this. Usually fired at temperatures of 1200-1300C.

Studio pottery;- pottery that has been individually designed and crafted.

Tazza;- a dish, shallow cup or vase on a pedestal, not always suitable for food use, 

Throwing;- the making of a hollow circular form on a rotating wheel, using centrifugal force against the wet hands of the potter.

Tooled;- detailed decoration applied with gilders tools after the application of the gilding.

Towing;- smoothing the surface and edges of flatwares (plates and platters) using tow (flax fibre).

Transfer printing;- the transfer of a pigment or ink from engraved wood or copperplate onto the wares by using a thin sheet of paper.

Translucent;- allowing some light to pass through an object but not enough to define shapes.

Tube lining;- type of decoration in which thin trails of slip are applied as outlines to areas of coloured glaze.

Tureen;- a deep covered dish used for serving food at the table.

Under glaze;- a design painted by hand before the the glaze is applied, generally in blue with few exceptions.

Uranium glass;- adding Uranium to the glass mix made yellow and green glass that fluoresced under ultraviolet light. There are many different brands of Uranium glass including, Annagrun, Annagelb, Chrysoprase, Vaseline and some Whitefriars.

Vent hole;- a small hole in an otherwise sealed hollow shape to allow the gases or air to escape as the ware shrinks in the kiln.

Vetro a retorti or Latticino;- the art of embedding white strands of glass in rods of clear, colourless glass.

Vitreous;- glass like.

Water slide;- the method of applying lithograph and silk screen transfers by soaking them from paper backing and sliding them into position on glost ware, (glazed pottery).

White ware;- white porcelain which has been glazed but not decorated, or simple white glazed domestic earthenware.

Wicker moulded;- wares moulded with a finish resembling wicker basket work in appearance.

Wreathing;- spiral indentations, a fault sometimes found on the sides of hard paste porcelain wares.

Zanfirico;- the art of embedding coloured strands of glass in rods of clear, colourless glass.