Important Notice: We are closed for Easter from Good Friday to Easter Monday inclusive. Order processing resumes Tues 23/04/19.

clays

Leading Suppliers

We have been renowned as leading suppliers of clay for nearly eighty years, most of these clays being based upon the unique deposits taken from our clay mines at Brownhills, South Staffordshire. In the last forty years or so we have however substantially increased our manufacturing capabilities to include the manufacture of a comprehensive range of glazes and a wide range of top quality kilns of both electric and gas fire types.

Whilst our product range is now very extensive we would however emphasise that our marketing strategy is based upon flexibility and we are able to produce clays, glazes and kilns to customers specification. If you therefore require a product not included in this catalogue or you require any amendment or modification, do please let us know. Our products are for potters, sculptors, tilemakers and ceramists in craft, education and industry. Generally we have sought to bring together a combination of our own manufactured products with a selection of other brand names, many from prestigious international suppliers for whom we are UK Distributors.

In addition we aim to provide much useful technical data so as to enable not only easier selection of the product most suitable for a particular requirement but also to provide important health and safety information. We endeavour to cater for all degrees of skill: for the expert we offer a wide range of clays, glazes, colours etc. suitable for use in advanced techniques and capable of giving superb results. On the other hand, we appreciate the difficulties of the novice and hence provide literature and technical advice to assist in the choice of materials, equipment and making methods. We also extend a cordial invitation to visit us at our Etruria showrooms. You would always be most welcome and could collect any requirements "on the spot" thus avoiding carriage charges.

Potclays Clay Mine

 

Potclays Clay Mine

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Selecting Clays

All our clay bodies are in plastic form, packed in 12.5 packs (9.25kg or 12.75kg for a few clays) and are ready for use. When stored in a cool but frost-free situation, free from draughts and direct sunlight, the clay packs will retain their condition almost indefinitely. For general use we particularly recommend 150-1102 Oxidising St Thomas and 151-1124 Sanded Buff bodies, both of which are slightly grogged. If a smooth clay is preferred then we suggest clays 159-1132 New Keuper Red, 159-1135 Original Red S/E, 159-1137 Red Earthenware Terracotta, 151-1120 Buff School Clay or 158-1141 Studio White Earthenware. For more specialised needs, the chart and data given in our catalogue will assist. Some clays have very wide firing ranges, enabling them to be used for earthenware (1100-1150C), middle temp.(1180-1220C) or stoneware (1220-1300C). These include:  

Buff firing: 150-1102, 151-1120, 151-1124, 157-1150

Red firing: 159-1132, 159-3240, 159-1134

White firing: 158-1141, 158-2144, 158-4130

Glaze Suitability/Firing Temperatures We recommend biscuit firing at 1000-1060C then following with a glaze firing to a higher temperature which matures both the clay and the glaze at the same time. Each clay body and each glaze is catalogued with its firing range. When selecting a glaze for use with a particular clay it is important to select one with a firing range which exceeds the lower figure given for the clay. If this is not done the clay will be underfired and the glaze consequently may craze. Alternatively one could biscuit fire the clay above the lower figure given for the clay then glaze fire to the firing range of the selected glaze. However, this method may cause difficulty with glaze pick-up when dipping (although this can be overcome: see product code 3442 in our catalogue). Bone china is invariably produced this way.

Click here for our clay selection chart.

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Firing Rate

The optimum rate depends upon the thickness of the pots and clay type e.g. thin cast and grogged bodies can be fired quicker than thrown and ungrogged ones. Ideally, biscuit firings would be slower than 100C per hour up to 200C and 100 - 200C per hour beyond that point and ending with a short soak. Glaze firings should be at 100-130C per hour but at 100C per hour maximum from 700-1100C with high carbon ball clay or fireclay based bodies.

Maximum Firing Temperature: This is approximately indicated by the vitrification point stated for each clay in our catalogue but, with stoneware, it will be lowered by reduction firing conditions and is dependent upon other factors such as firing cycle. Consequently this figure is given only as a guide for comparison purposes. If clays are fired above their vitrification point then bloating is likely. Bloating may also result from insufficient biscuit firing or too fast firing in the later stages of the glost firing. Conversely, overlong firings may give excess heat work and cause bloating.

Recipe Amendment Recipes of heavily grogged panmilled bodies 153-1114, 153-1153 and 154-1154 were amended from May 1998 to give improved resistance to lime popping and efflorescence problems. These changes involve using new refractories instead of reclaimed firebrick as the grog source, finer processing of certain other clay constituents and the intoduction of a new version of Craft Crank, which is now listed as 153-3114 Premium Craft Crank. The fired colour may be slightly different under certain firing conditions and a fired trial is therefore recommended. Other properties, including their superb handbuilding performance, remain the same.

Manufacturing Methods: Bodies marked P are finished by our Panmilling technique. This gives excellent, reliable control of grog and water contents but is more open to occasional contamination from larger or extraneous particles arising in the ingredients or during processing. It generally produces better moisture control in grogged bodies. S denotes Sliphoused bodies. These are prepared in very large batches in slip form which is finely sieved prior to or after grog addition. The purified slip is then pumped into presses for dewatering prior to pugging. Sliphousing gives greater product uniformity and virtually guarantees freedom from contamination. Its disadvantage is that it is more difficult to control grog contents (due to settling from suspension) and moisture content. It is the best technique for smooth textured bodies. See table.

Some bodies are now produced by a Plastic Blending process, which yields bodies offering the high purity and cost effectiveness of a sliphoused product together with the ultra-tight control over grog additions previously only possible by panmilling.

 

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PREPARED CLAY BODIES - Descriptions

St Thomas™ Clays

Oxidising St Thomas™ 150-1102 Extremely popular general purpose high earthenware and stoneware body which produces an attractive speckle under normal or slightly reducing conditions. Both tolerant and resilient it has good warp and crack resistance and is suitable for throwing and slabbing.

Reduction St Thomas™ 150-1104 An attractive toasted stoneware in oxidising conditions this body really comes into its own under reduction. The excellent handling properties make it a popular choice for domestic stoneware production.

White St Thomas™ 150-1106, 150-1506 A light grey-white colour in both oxidation and reduction combined with outstanding handling and resilience make this body the first choice for small and large work alike. The 150-1506 version is particularly free of natural speckles, and both will withstand high temperatures.

General Stoneware

Buff Stoneware 151-1117 An inexpensive fireclay based body which throws well, turns easily, and is plastic, strong and reliable making it highly suitable for domestic ware.

Buff School Clay 151-1120 Popular with stoneware potters as a production body for both oxidation and reduction, this dual purpose earthenware and stoneware clay is equally suited to use in schools. The fireclay, ball clay and china clay blend produces a body of smooth texture and medium shrinkage.

Sanded Buff 151-1124 A lightly sanded version of our Buff School Clay, this body has a much greater tolerance to making methods and is an excellent choice for school use.

Lavafleck™ 151-1514 This new version of our highly flecked stoneware body is popular for its distinctive character. Having good throwing ability, it is now more temperature stable. Shelves need to be well coated with refractory wash to prevent sticking during firing.

Throwing Stoneware

Flecked Stoneware 152-1109, 152-2109 Based on a blend of ball clays, this attractively flecked body is excellent for thrown domestic ware, large or small pieces. The carefully graded fleck burns through covering glazes giving a reduction fired appearance in an oxidised firing. The 152-2109 version is similar to 152-1109 but is based on higher purity sliphoused materials and is more attractively priced. Stoneware Body 152-2110 This highly plastic throwing body designed for use in oxidised and reducing conditions, is suited to thrown domestic ware particularly where colour response is important.

Staffordshire Stoneware 152-1115 This highly plastic blend of ball clays with a small addition of red clay, is manufactured using our Plastic Blending Process to produce an attractively toasted clay. Suitable for both oxidising and reduction firings up to 1300C it has good thermal shock resistance making it an ideal candidate for small to medium sized domestic ware.

Coloured Earthenware Clays

New Keuper Red 159-1132 This high quality, smooth earthenware body has a low flux content to improve glaze pick-up and enabling it to be used at higher temperatures. When fired above 1200C the body takes on a purple tone.

Keuper Sanded Red 159-3240 Superb body for tiles, slab work, large pieces and murals alike, this body has high resilience and good warp resistance, yet the smooth texture allows detail to be captured.

Grogged Red 159-1134 When used at either earthenware or stoneware, this body has good general properties, low shrinkage, and is excellent for large pots. Firing to a terracotta colour at earthenware the colour gradually changes with increasing temperature to a warm toasted brown.

Original Red S/E 159-1135 Carefully graded and blended red clays and fireclays give this, our original terracotta body, outstanding tolerance and physical properties. It is a good domestic earthenware body which throws and turns well.

Red Earthenware Terracotta 159-1137 This competitively priced body is a high quality blend of red clays and fireclay which give it a good colour and high fired strength.

Sanded Red 159-3730 Based on our 159-1137 body, a small addition of sand enables this body to be used for larger forms and increases warp resistance making it suitable for tile production without detracting from the pleasant terracotta colour.

Chocolate Black 159-2130 Especially good for sculpture this competitively priced clay fires to a chocolate black colour at earthenware temperatures and has a fine texture.

Crank Clays

Ivanhoe Tile Body 153-2112 This traditional formulation is superb for tiles, slab work and murals due to its excellent warp resistance and resilience. Although it has a high grog content, the smooth surface texture allows detail to be captured well in the toasted colour.

Craft Crank™ 153-1114, 153-2114 Regarded by many as the best crank clay available, Craft Crank™ is unsurpassed as a handbuilding clay. The unique blend of fireclays and ball clays produce a pleasant toasted colour in oxidation whilst the speckled orange-brown under reduction is unrivalled. The 153-2114 version is similar to 153-1114 but is based on higher purity sliphoused materials and is more attractively priced.

Premium Craft Crank 153-3114 This body offers the same properties as our original Craft Crank, but with an all ball clay base. This gives the body a smoother clay base whilst retaining the same fired colour.

Sculpture Crank 153-7070 A variation of our Craft Crank specially formulated for larger sculptural work. It contains slightly more coarse grog grades than Craft Crank and has a more open texture.

Grogged Pink 153-1127 Obtained by a carefully controlled blend of Crank and red clays, it is a general purpose handbuilding body, which fires to a pleasant pink colour at lower temperatures and gradually darkens as the temperature increases. Responds wonderfully to high temperature wood firing, giving a rich purple-brown colour.

Industrial Crank 153-1153 Suitable for large sculptural work, slabbing, saggars and raku, this body is very refractory having an open texture with low shrinkage and good warp resistance.

Raku

Original Raku 154-1154 With superb thermal shock resistance and low shrinkage this body is not only excellent for raku work, but is also highly suited to slabbed work and is capable of firing to stoneware.

Coarse Raku 154-1156 With coarser grogs present, this body is designed for those producing large sculptural forms which are intended for either raku or stoneware firing. The coarse textured grogs produce a pronounced fleck when fired to stoneware.

Smooth Raku 154-1159 Specifically designed for those who want the strength and resistance for raku firing but in a body which can be thrown, slabbed and coiled, it contains more medium range grogs.

Tandoori 154-0131 (only available by the tonne) Intended for industrial applications, this body is specially designed for the production of Tandoori ovens where high strength and excellent thermal shock resistance is required. This very coarse body is not recommended for general use or for sculptural items where a high selling price is anticipated.

White Grogged Stoneware

White Crank 156-0630 White firing, this body is based on a blend of ball clay and china clay to which is added graded molochite grogs. It is excellent for the production of large forms, slabs and tiles, and can be fired to stoneware as well as used for raku.

T Material 156-1161 Extremely resilient and tolerant, this off-white firing body is superb for large sculpture and handbuilding use. Its low thermal expansion, low shrinkage and good warp resistance mean that it is well suited to high quality raku pieces.

Y Material 156-2161 White firing, this blend of ball clays and china clay with molochite grogs is the ideal choice for high quality raku pieces. Its low shrinkage and excellent warp resistance combine well to produce an outstanding sculptural body.

Porcelain

DL Porcelain 155-1147 Similar to the original David Leach body, this white, translucent porcelain is excellent for throwing.

HF Porcelain 155-1149 This truly excellent white-burning translucent porcelain developed by Harry Fraser combines the finest quality and value. It throws well and is consistent and reliable.

JB Porcelain 155-4000 Whiter firing than almost all other porcelains, this body offers good throwing properties combined with high translucency and quality at an affordable price.

Bone China 155-1148 This traditional Stoke-on-Trent Bone China body offers users the whitest firing clay available. Like all bone china, it is best suited to slip casting or machine making, but with suitable plasticiser additions it can be converted to a "flower making" clay.

White Stoneware

White Stoneware 157-1145, 157-2145 This superb white stoneware body, based on carefully selected china clays and ball clays, has just sufficient added flux to maintain temperature stability yet provide exceptional ring. Excellent for small and large thrown domestic ware it stand up well even when thrown thinly. The 157-2145 version is similar to 157-1145 but is based on higher purity sliphoused materials and is more attractively priced.

White Special Stoneware 157-1142, 157-4230 White firing and smooth textured, this clay throws and handles well and is a very good body for domestic ware. The 157-4230 version contains a small amount of white sand which provides extra shape stability for larger domestic ware and improves the thermal shock resistance.

Draycott White Stoneware 157-1143 A white firing blend of ball clay, china clay and fireclay, to which a small addition of molochite grog is made, produce a smooth body suitable for throwing and modelling both small and large domestic items for oxidised or reduction firings.

Modelling Clay 157-1150 Used by model makers for all types of projects, from original china figure models to film special effects, this clay is the most plastic modelling clay available. Used by Tussauds in the production of their waxworks.

White Earthenware

Ivory Earthenware 158-4138 A good earthenware body for slip casting of general and domestic ware.

Studio White Earthenware 158-1141 This ball clay based, very plastic white firing earthenware is well suited to thrown ware. It has a good green strength and wide firing range.

Grogged White 158-4130 Based on the 158-1141 to which we add a small addition of graded white grog, this body has exceptional handling properties for larger items and yet can still be easily thrown.

Grogged White (Molochite) 158-4120 Graded molochite grogs are included in the 158-1141 base clay to give a body which has excellent workability for handbuilding, sculpture and tiles, yet still possesses a high plasticity for throwing.

Semi-Porcelain 158-2144 A white earthenware, semi-porcelain or Parian body made to a traditional recipe which is generally suited to slip casting or machine making. Smooth in texture but of medium plasticity.

Paper Clay

Paper Clay 180-1190 Developed in conjunction with paper clay users, this body is based on a white stoneware to which carefully controlled grades of inorganic fibres and binders have been added to extend shelf life.

 

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Powdered Clay Bodies

190-1000 Low temperature white e-ware Fires white to off-white from 1020 - 1180C. Good for engobing red clays, etc. 190-1118 Buff Earthenware/Stoneware General purpose clay suitable for earthenware or stoneware. Firing range 1110 - 1285C. 190-1135 Red E/W Firing range 1050 - 1170C. 190-1140 White earthenware Firing range 1110 - 1260C. 190-1145 White Stoneware Powder Firing range 1210 - 1300C. 190-1146 Porcelain Firing range 1170 - 1220C. Low temperature porcelain for slipcasting. Sieve through 60s mesh sieve. 190-1149 H.F.Porcelain Firing range 1220 - 1290C. Should be slipped through 60 mesh or finer to give a strong, white translucent porcelain.

Raw Clays

Fireclays, Ball clays and China clays: Specially selected for use in bodies or glazes. All are in powdered form. See our catalogue for analyses. 1273WAD Fireclay N6 Our N6 fireclay supplied in plastic form. Fires buff-grey with strong speckle at stoneware. Tremendously plastic. 3406 Ball Clay (ESVA) 3407 Ball Clay (Hyplas) Approximately 70% SiO2. 3408 Ball Clay (HVA/R) 3409 Ball Clay (AT) High iron content.

3416 China Clay A general purpose china clay for use in bodies or glazes. 3416-3 Grolleg China Clay 3416-4 Porcelain China Clay White firing china clays of world-wide reputation. Both are exceptionally white yet reasonably plastic.We process large quantities of fireclays from our mines and additionally use a wide range of ball clays and china clays. Please let us know if there is a particular product you need which is not listed here.

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Air Hardening Clay

165-1187 Creative Clay™airdrying clay (grey) and 165-1188 Creative Clay (red). Creative Clay™is an air-drying clay which we have developed using the highest quality materials available. Essentially a standard potters' modelling clay with an addition of nylon fibres to provide exceptional bonded strength when dry and unfired. These nylon reinforcing fibres are an excellent bonding agent which reduces brittleness and means that the clay need not be fired. It is an ideal modelling medium for both children and adults, and can be painted and/or varnished once dry. Creative Clay can also be thrown, moulded etc. For more durable pieces, the clay can be fired and glazes applied. The firing range of Creative Clay™is 1000C to 1280C for the grey version and 1050C to 1170C for the red.

1185-1 Newclay™A popular modelling clay which contains nylon fibres which much increases the strength when dry. Can be decorated when dry with non-firing stains, acrylics, tempera colours etc. Dry clay can be reconstituted. 1185-3 Newclay™ Hardener When dissolved in hot water and painted onto Newclay this product further increases the strength of the piece. 1183-4 Newclay™ Gloss Sealer Paint on to seal pieces made with Newclay to give a glossy finish.

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Grogs

Calcined China Clay/Molochite Grogs

Used as clay substitute to lower shrinkage of engobes etc. The coarser grades are used as very pure white grogs.

3447-022 Molochite 22-60 | 3447-030 Molochite 30-80 | 3447-120 Molochite 120 | 3447-200 Molochite 200 

Hi-Pur Grogs

Firing to a light grey-white colour and of exceptional purity, our Hi-Pur range offers the ultimate in grog material. Virtually guaranteed lime-free, this carefully graded material allows the coarsest of clay blends to be prepared with complete peace of mind and with the confidence that there will be no nasty surprises from impurities.

1251 18-36 | 1252 30-80 | 1253 5-dust

NOTE We no longer use or supply firebrick grogs.

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Casting Slips

Prepared to a specific gravity of 1.7 - 1.8 ( 34 - 36ozs per pint). Supplied in polythene containers, these slips are correctly deflocculated ready for use but in certain circumstances it may be desirable to thin them slightly, in which case add just a few drops of Sodium Dispex per gallon. 160-0200 Potclays White 1040 - 1140C 160-1200 Low Temp White 1060 - 1140C 160-1201 Chocolate Black Earthenware 1040-1120C 160-1202 Red Terracotta 1050-1170C 160-1203 White Earthenware 1100-1260C 160-1204 Parian-Semi porcelain 1100-1240C White earthenware with extra fluxes for greater vitrification. 160-1205 Buff Earthenware-Stoneware 1110 - 1285C 160-1206 Stoneware 1200 - 1290C 160-1208 Porcelain 1220 - 1290C 160-1210 Bone China 1200 - 1250C.

Casting Slips are produced by adding about 0.25% - 0.5% of deflocculant and also water to powdered or plastic clay. Over-addition of deflocculant causes cracking and sticking of casts on the mould. Under-addition is sometimes desirable but causes slips to thicken on standing although they will thin again on stirring (i.e.thixotropic).Sodium Silicate and Soda Ash are the usual deflocculants but we strongly recommend Sodium Dispex for topping-up addition and slip adjustment. Coloured Decorating Slips Clay-water slips for dipping and trailing in the manner of traditional slipware. Compounded from earthenware bodies but capable of firing to stoneware. Water may be added or removed to alter the consistency. Under certain conditions dilution may be desirable to avoid flaking.

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