C201 Ball Clay - Hyplas 71 (S) A very plastic Devon Ball Clay giving good strength and plasticity to bodies especially useful in preparing clay for larger thrown ware. Fires to light ivory colour. Also for use in glazes. Low iron content.
C203 Barium carbonate (X, C, T2) Poisonous. A secondary flux in stoneware and porcelain glazes used generally to produce a vellum matt glaze surface. Small quantities are used (up to 2½%) in some clay bodies to prevent scumming arising from soluble salts.
C205 Batt Wash (S) A specially blended wash mixed with water and painted on to kiln shelves. Helps prevent pots sticking to shelves and prolongs shelf life.
C206 Bentonite (S) Decomposed volcanic ash. Highly colloidal material of extreme plasticity. Added to glazes as a suspending agent (up to 3% by weight) and into clay bodies to improve plasticity (up to 5%)
C207 Bone Ash (Calcium Phosphate) (S) A secondary flux in glazes, occasionally used as an opacifier. The essential constituent used to produce translucency in bone china bodies (calcined).
C209 China Clay (S) A selected white-burning residual clay of above average plasticity, ideal for producing white earthenware and porcelain bodies. Also for use in glazes and bodies.
C210 Colemanite (Calcium Borate) (S) Boro-calcite. A useful and powerful flux in glazes introducing an insoluble form of boron with calcium.
C211 Cornish Stone (Pegmatite) (SX) Decomposed granite. A specially defluorinated product for extra safety. Used as a secondary flux in glazes and as an alternative to feldspar in both bodies and glazes. Not as fusible as feldspar due to high silica content. In dust form it is hazardous if beathed in.
C212 Dolomite (S) Calcium Magnesium Carbonate. Used as a secondary flux in stoneware glazes.
C213 Feldspar Potash FFF (S) Feldspar is the major flux in clay bodies and high temperature glazes, some of which contain 70% or more feldspar. Potash feldspar is the one generally used and recommended. The terms "potash", "soda", "lime" denote the principa, but not the only, flux present. FFF is a blended grade of high consistency.
C214 Fireclay (S) A refroctory clay used as an additive to stoneware bodies to produce a more open texture and speckling, especially under reduction. Fires to a warm buff brown but darker under reduction.
C215 Flint (SX) Silica. Very refractory material used to provide silica in bodies and glazes. Increases firing temperature and craze resistance. In dust form it is hazardous if breathed in
C216 Glaze Binder (Additions of up to 2% of the dry weight of glaze increase the adhesion, viscosity and hardness of the unfired glaze. 5% addition recommended for glaze application by brush.
C219 Gum Arabic (S) An alternative glaze binder, can be added to correct or improve the consistence of a glaze. Old dry glaze can also be restored by adding a few drops of water and gum.
C220 Lithium Carbonate (SC) A good alkaline flux used as a substitute for soda and potash when good craze resistance is required.
C223 Mouldmakers Size A high quality size used in the production of plaster moulds to prevent sticking of the two plasters.
C224 Nepheline Syenite (S) Mineral mixture of feldspar and hornblende with little silica. More fusible than feldspar, it can be used as a replacement to reduce the maturing range of glazes and bodies.
C226 Quartz (SX) Silica. Introduces silica as an alternative to flint in glazes. In Dust form it is hazardous if breathed in.
C227 Rutile (S) An ore containing titanium dioxide with iron oxide, used to produce a mottled buff brown colour (3-8%) especially in presence of ilmenite. Increases opacity of glaze. Exciting effects may be achieved in combination with stains or colouring oxides.
C228 Silica Sand (S) Buff, medium fine, producing speckles and ideal for opening bodies instead of grog.
C230 Soda Ash (Sodium Carbonate) (SC) Used in the preparation of casting slip in combination with sodium silicate. Its solubility in water makes it effective as the alkaline glaze constituent of Egyptian Paste.
C232/75 Sodium Silicate 75TWD (S) A deflocculent used in the preparation of casting slips. Mls to gms multiply by 1.38. Used in Bone China slips.
C232/140 Sodium Silicate 140TWD (S) Mls to gms multiply by 1.5. Used in Earthenware slips. Mls to gms multiply by 1.7. Used in Stoneware slips.
C233 Talc (T1) French chalk. Soapstone. Magnesium silicate secondary flux introducing magnesium and improving craze resistance of glazes. A flux for clay bodies especially flame proof and low temperature ones.
C235 Wax Emulsion Resist (S) A masking medium used to paint areas on which no glaze is required.
C236 Whiting (S) Chalk. Limestone. Calcium carbonate. Main source of calcium in glazes and extensively used as a flux in stoneware and porcelain glazes. Assists hardness durability and in large quantities produces mattnes.
C238 Zinc Oxide (T2) Only available source of zinc for glazes. A secondary flux, but above 10% tends to produce a frost-like matt surface, a degree of opacity and occasional pinholing.
C240 Lead Bisilicate 880-1050˚C (X, C, T3) Lead bisilicate is a good clear lead frit, which it generally used in low soluable glazes.
C241 Standard Borax Frit 900-1100˚C (X, C, T3) Standard borax is a good general purpose frit, which is generally used in leadless glazes.
C242 High Alkaline Frit (X, C, T3) High expansion frit excellent base for crackle and raku glazes. Na20.58 K2 0.21 Ca0.105a1203.093, Si02 1.66 B203.105
The raw pigments from which prepared colours and stains are compounded, oxides may be painted directly onto clay biscuit ware or glazed ware (majolica), or used as a stain for bodies and glazes producing the characteristic colours described.
Copper Oxide must not be incorporated into any low solubility glaze if the resulting glaze is to be used on domestic wares in contact with food or drink. On non-contact surfaces and in leadless glazes there is no problem
C249 Antimony Trioxide When added to a rich bad glaze by 10-20%, a bright yellow colour is the result.
C250 Chromium Oxide Versatile pigment producing characteristic opaque green but producing red and yellow in some lead glazes and brown in the presence of zinc. Incorporation with tin produces pink (chrome tin pink)
C251 Cobalt Oxide (Black) (S) The most powerful ceramic pigments giving a range of transparent blues ranging from intense blue or blue-black in lead and leadless glazes to a vivid blue in alkaline ones. The carbonate form is weaker but gives less risk of speckling.
C252 Cobalt Carbonate (S) A very strong pigment giving the colour blue. Cobalt carbonate is not as strong as Cobalt Oxide.
C253 Copper Carbonate A weaker form of Copper Oxide.
C254 Copper Oxide (Black) Cupric Oxide. Transparent green under normal neutral or oxidising firing conditions except in alkaline glazes where turquoise is developed deepening to transparent Persian Blue in strongly alkaline ones. Under reduction conditions a copper red colour is obtained (sometimes referred to as ox-blood or sang-de-beef). Carbonate form is weaker but gives less risk of speckling.
Iron compounds have a great natural variety and are the most popular colouring pigments in addition to the characteristics detailed below, most of them produce yellow/tan tints (depending on quantity and thickness) in lead/tin glazes. As stoneware temperature black/brown tenmoku effects are developed whilst black and grey/greens are achieved under reduction firing conditions.
C256 Iron Oxide(Black) (S) Ferrous Oxide. Greater iron content which produces darker shades than red iron oxide.
C259 Iron Oxide (Red) (S) Hematite Ferric Oxide. Very popular form of oxide producing colours from honey to dark brown.
C263 Nickel Oxide (X) Will produce brownish greens, browns and grey in glazes but more commonly used to modify or grey the colours obtained from other colouring oxides by combination.
C264 Tin oxide (S) Stannic Oxide. Generally used as a white opacifier for glazes but also useful as a white decorative pigment either alone or mixed with a little transparent glaze.
C265 Vanadium Pentoxide (XC) Generally used in combination with tin oxide in glazes to give opaque yellow but also directly as a pigment.
HEALTH AND SAFETY
A suitable mask and PPE should always be worn whenever handling finely ground ceramic materials. Please pay special attention to all safety instructions. The following codes indicate the degree of hazard of certain materials.
S Safe when handled as stated above
X Particularly harmful if inhaled
C Corrosive to skin, eyes, etc
T Toxic - T0 very slightly, T1 slight, T2 moderate, T3 high