Green.—The clay shapes before biscuiting. Jigger.—The wheel on which shapes are moulded with the aid of a jolley or profile. Joggle.—The natch or key in a mould to insure correct adjustment and prevent slipping. Lawn.—The fine mesh gauze through which glazes are strained. Long.—A clay is termed long if very ductile and tenacious. Muffle.—Usually the fire-clay box or interior of a small kiln, but applied to any kiln to the inside of which the flames have no access. Natch. (See Joggle.) Oxidizing.—The ordinary method of firing gives an atmosphere in which there is always sufficient oxygen to consume all the carbon or combustible gases. If oxygen is present in excess, it causes reactions known as oxidizing. Pitchers.—Finely ground biscuit. Added to some clays to increase refractories or porosity. Moulds made in such clays and fired are termed pitcher moulds. Potsherds.—Any broken biscuit or pot, sometimes used for pitchers. Potting.—A colloquialism used to designate the ceramic industry. Pugging.—The roll of infusible clay placed between each saggar when building bungs. Reducing.—The reaction that accompanies the introduction of smoke or gas containing carbon in a very finely divided state into a kiln during the process of firing glaze. Reduction is now widely employed in obtaining fine lustre effects. Refractory.—Hard, infusible.
Rich.—Used of clays that are long and fusible, such as red clays. Riffle.—A grooved and toothed plaster tool of steel. Saggars.—Or seggers. The fire-clay receptacles in which the glazed ware is set during the firing. Setters.—Supports used when packing friable biscuit. Short.—A word used to denote a clay that crumbles or is difficult to pull up on the wheel. Sieve.—Sometimes called a lawn, more correctly a screen for clay or slip. Slip.—The sieved clay or paste in creamy liquid condition as used for slip decoration, engobes, or casting. Slub or Slurry.—Clay mixed with water but not sieved, as with slip. Spy.—The small hole, kept plugged, through which tests and cones are observed. Stunt.—Or dunt. To crack or split on cooling. Turning.—The shaving down of the clay shape on a lathe, to impart lightness and finish. U. G.—Under-glaze (applied to colours). Vent.—A hole to aid the even distribution of fire in a kiln or to accelerate the cooling off. Waster.—Commercially, a spoiled pot; defective ones are termed “seconds.” Wedging.—The beating or slamming operation usually employed to expel air or correct inequalities just before clay is used by the thrower. Whirler.—A circular support pivoting on its centre, used in casting or banding; similar to a banding wheel, but usually heavier.
MATERIALS, TERMS, ETC.
C = Combining Weight
E = Equivalent Weight
| Symbol | C or E | Fusing Point | |
| Alumina (calcined) | Al2O3 | C 102 | Very infusible |
| Alumina (hydrated) | Al2O3·3H2O | C 156 | |
| Aluminium | Al | E 27 | 627° C. |
| Ammonia | NH3 | Volatile | |
| Antimony | Sb | E 120 | 432° C. |
| Antimony oxide | SbO | ||
| Arsenic | As | E 75 | 500° C. |
| Barium (metallic element) | Ba | E 137 | Fuses above red heat |
| Barium carbonate | BaCO3 | C 197 | |
| Barytes | BaSO4 | C 233 | Fuses about white heat |
| Bauxite | |||
| Bismuth | Bi | E 28 | |
| Borax (crystals) | Na2B4O7·10H2O | C 382 | Very fusible |
| Boric acid (crystals) | B2O3·3H2O | C 124 | |
| Boric acid (dry) | B2O3 | C 70 | High fusing point |
| Boron (metallic element) | B | E 11 | |
| Calcined bones | Infusible | ||
| Calcined kaolin China clay (fine) | Al2O3·2SiO2 | C 222 | Very infusible slightly vitreous at highest fire |
| Calcium oxide (lime) | CaO | C 56 | Very refractory if alone but fusible with clays |
| Calcium carbonate | CaCO3 | C 100 | |
| China stone Cornish stone | 8SiO2·2Al2O3·K2O | 1379 | 1300° C. about |
| Chrome oxide | Cr2O3 | C 79 | |
| Chromium | Ca | E 51 | Above platinum |
| Cobalt | Co | E 59 | 1500° C. |
| Cobalt oxide | Co2O3 | C 165 | |
| Cobalt oxide (black) | Co2O4 | C 240 | |
| Copper | Cu | E 63 | 1054°-1084° C. |
| Copper oxide (black) | CuO | C 79.5 | |
| Earthy colourants | |||
| Ochres | |||
| Siennas | |||
| Umbers | |||
| Felspar | 6SiO2·Al2O3·K2O | C 556 | 1200°-1300° C. about, according to purity |
| Flint (calcined) | SiO2 | C 60 | 1830° C. about |
| Fluorspar | CaF2 | Much lower than felspar | |
| Galena (lead sulphide) | PbS | Very fusible | |
| Gold | Au | E 147 | 1054°-1075° C. |
| Gypsum (plaster of Paris, if calcined) | CaSO4·2H2O | C 172 | |
| Iron | Fe | E 56 | 1530°-1600° C. about |
| Iron oxide | Fe2O3 | C 160 | |
| Iridium | Ir | E 193 | 1950° C. about |
| Kaolin (see calcined kaolin) | Al2O3·2SiO2·2H2O | C 258 | Infusible |
| Lead (metal) | Pb | E 206 | 326° C. |
| Lead carbonate | PbCO2 | ||
| Lead, red oxide of | Pb3CO4 | ||
| Lime (see calcium oxide or carbonate) | CaO | ||
| Lynn sand (see silver sand) | SiO2 | ||
| Magnesia (calcined) | MgO | C 40 | 430° C. |
| Magnesia (carbonate) | MgO·CO2 | ||
| Manganese, carbonate | MnCO3 | C 115 | |
| Manganese (metal) | Mn | E 55 | 1670° C. about |
| Manganese oxide (or black) | MnO2 | C 87 | |
| Nickel (metal) | Ni | E 58 | 1427°-1450° C. |
| Nickel oxide | NiO | C 75 | |
| Nitre | KNO3 | ||
| Pearl ash or potash | KOH | ||
| Plaster of Paris (calcined gypsum) | CaSO4·1⁄2H2O | C 145 | |
| Platinum | Pt | E 197 | 1710°-1775° C. |
| Potash, bichromate of | K2Cr2O7 | Fuses dull-red heat | |
| Potassium carbonate | K2CO3 | C 138 | |
| Potassium oxide | K2O | C 94 | |
| Quartz Quartz sand | SiO2 | C 60 | 1830° C. about |
| Rutile (see titanium) | |||
| Salt | NaCl | 776° C. | |
| Silica | SiO2 | C 60 | |
| Silver sand (or quartz sand) | SiO2 | ||
| Silver (metal) | Ag | E 107 | 945°-962° C. |
| Soda ash (calcined) | Na2CO3 | C 106 | |
| Soda crystals | Na2CO3·10 H2O | C 286 | |
| Sodium oxide | Na2O | C 62 | |
| Tincal (see borax) | |||
| Tin (metal) | Sn | E 119 | 233° C. |
| Tin oxide (white) | SnO2 | C 150 | |
| Titanium oxide (rutile) | TiO2 | Infusible | |
| Uranium (metal) | U | E 239 | 1800° C. about |
| Uranium, oxide of | U3O8 | ||
| Whitening (see lime carbonate) | |||
| Zinc (metal) | Zn | E 65 | 443° C. |
| Zinc oxide (white) | ZnO | C 81 |
SEGER CONES. (STANDARD CONES. ABOUT 10° HIGHER.)
Numbers. Turning Points. Colour, etc.
| Centi- grade | |||||
| Commences to show colour | ╔ | .022 | 600° | ╗ | Soft enamel or over-glaze colours. |
| ║ | .021 | 650° | ║ | ||
| ╚ | .020 | 670° | ╝ | ||
| Dull red | ╔ | .019 | 690° | ╗ | Enamels on metals. Fluxes and lustres. |
| ║ | .018 | 710° | ║ | ||
| ║ | .017 | 730° | ║ | ||
| ╚ | .016 | 750° | ║ | ||
| Red to cherry | ╔ | .015 | 790° | ╝ | |
| ║ | .014 | 815° | ╗ | Very soft glazes and hard enamel colours. Some lustres. Gilding. | |
| ║ | .013 | 835° | ║ | ||
| ║ | .012 | 855° | ║ | ||
| ║ | .011 | 880° | ║ | ||
| ╚ | .010 | 900° | ╝ | ||
| Dull cherry to light cherry | ╔ | .09 | 920° | ||
| ║ | .08 | 940° | |||
| ║ | .07 | 960° | ╗ | Majolica glazes or coloured glazes and stanniferous or tin glazes. | |
| ║ | .06 | 980° | ║ | ||
| ║ | .05 | 1000° | ║ | ||
| ║ | .04 | 1020° | ║ | ||
| ║ | .03 | 1040° | ╝ | ||
| ╚ | .02 | 1060° | ╗ | Earthenware glazes. Soft China glazes. | |
| Dark orange to pale orange | ╔ | .01 | 1080° | ╝ | |
| ║ | 1 | 1100° | ╗ | Soft to hard or fine earthenware biscuit. | |
| ║ | 2 | 1120° | ║ | ||
| ║ | 3 | 1140° | ╝ | ||
| ║ | 4 | 1160° | |||
| ╚ | 5 | 1180° | Sèvres soft bisque. | ||
| Yellowish white | ╔ | 6 | 1200° | ╗ | Vitreous ware. Granite ware. Salt glaze. Stoneware. |
| ║ | 7 | 1230° | ║ | ||
| ║ | 8 | 1250° | ╝ | ||
| ╚ | 9 | 1280° | English bone porcelain or China biscuit. | ||
| White | ╔ | 10 | 1300° | ||
| ╚ | 11 | 1320° | |||
| Intense white | ╔ | 12 | 1350° | ╗ | German and Chinese porcelain. |
| ║ | 13 | 1380° | ╝ | ||
| ╚ | 14 | 1410° | Sèvres porcelain. | ||
| 15 | 1430° | ||||
| Bluish white | ╔ | 16 | 1460° | ||
| ╚ | 17 | 1480° | Copenhagen porcelain. |
To convert temperatures:
Centigrade into Fahrenheit.—Divide by 5, multiply by 9, and add 32.