Appendix II
Glossary
Alumina, or Oxide of Aluminium, is one of the most abundant of earths. Combined with silica it is the chief constituent of kaolins and China clays. It imparts refractory qualities to clays and is an indispensable ingredient of pure glazes. Pure alumina or calcined Aluminium is a chemical product. Ammonia.—A volatile gaseous matter, found in some clays. Alkaline in action. Antimony.—A silver-white metallic element, used with other oxides as a colourant or to give opacity in glazes. Arsenic.—A non-metallic volatile element, used in glaze making. Barytes.—A heavy spar used with clays to introduce density and vitrescence. Bauxite.—A very aluminous earth, used in preparation of pure alumina and to render clays refractory. Boracic Acid.—The natural and, usually, impure product (boric acid being free from chemicals). Borax.—The combined chemical product of soda and boracic acid. Used as a strong flux in glazes. Calcined Bones.—The residuum of burned bones, used to stiffen artificial porcelain. Calcined Kaolin.—Kaolin after it has been subjected to heat to drive off the water combined with it. Calcium Carbonate (Whiting).—Found as a white rock, and ground to pure powder. Used with clays for soft bodies. Gives durability to glazes. Calcium Oxide (Lime).—A widely distributed earthy matter. Imparts fusibility to clays, in nearly all of which it is present in varying proportions. Chrome, Oxide of.—Used in making greens, browns, and blacks. Stands a high fire. Clays: Ball Clay.—Blue and black. Very plastic clays. Used with non-plastic materials, such as flint, stone, felspar, or whiting, to form fine earthenwares. Cane and Red Clays.—Clays coloured by the presence of ferric oxide, and used extensively for bricks, terra-cotta tiles, and common pottery. China Clay.—A yellowish-white, non-vitreous clay, product of the decomposition of granitic or felspathic rocks. Cornish China clay is exceptionally white, pure, and plastic. It is widely used with China, or Cornwall stone and calcined bones, to make bone porcelain. Felspar is added to render it vitreous. Mixed with ball clays, pipe clays, flint, and stone, it makes the various classes of earthen and stone wares. Pipe Clay.—A very white, smooth clay. Less plastic than ball clays. Much used for making slips, engobes, and enamels. Saggar Clays or Fire Clays.—Coarse refractory clays strengthened by the addition of grog, used for saggars, fire tiles, and bricks. Cobalt Oxide.—The oxide of the steel-grey hard metal. Extremely valuable in pottery, making all shades of blue for under-glaze printing or staining. With iron or copper gives blue-greens. Copper, Oxides of, and Carbonate.—Red, green, and black oxides of copper have been of the utmost value to potters. They are used to produce green, blue, turquoise, red, and crimson. Its extraordinary changes in reducing or oxidizing fires are of the greatest interest to the experimenter. Cornish or China Stone.—A rock composed of felspar and quartz. Its vitrification (about 1400° C.) imparts hardness and density to China clays. It is a valuable constituent of glazes. First known as “moorstone” or “growan.” Earthy Colourants.—Rarely used in modern commercial pottery, except for salt-glazed jars, crocks, and peasant pottery. Felspar.—A fusible rock found almost pure or in combination with potash and soda, the greater the percentage of alkalies the more fusible being the spar. It is used to replace more refractory materials in clay and to stiffen glazes. Flint.—A pure silica with slight traces of calcium. Found in pebble form on seashores. Calcined and ground to a white powder, it is widely used to impart whiteness and strength to clays. Invaluable for bedding and packing in kilns. Used with the fluxes,—lead, borax, potash, and soda,—to make glazes and glass. Fluorspar.—A combination of fluorine and calcium, more fusible than felspar, and of a white colour, felspar being pink. Galena.—Lead sulphide, a highly poisonous material used on “peasant” pottery, giving a soft, yellowish, transparent glaze. Gold.—Used in solution for delicate purples and lustres. Gypsum.—When calcined gypsum becomes plaster of Paris, these two materials, together with the allied marble, limestone, and alabaster, are widely used in pastes (such as Parian), slips, engobes, and variously to impart fusibility or colour properties to glazes. Iron, Oxides of.—Have a wide range of colour, from yellow to purple. They are used to stain glazes and colour bodies. They impart fusibility to clays and are carefully excluded from fine white bodies. Kaolin.—A fine, white, very pure, and infusible China clay, almost pure alumina and silica. Chiefly used in the manufacture of porcelain and fine earthenware. Lead (Oxides and Carbonates of). White Lead, Red Lead, Litharge.—Are very widely used as a safe and cheap flux. Poisonous. It cannot be used in those glazes that have to stand a high fire. Lime. (See Calcium.) Lynn Sand. (See Quartz Sand.) Magnesia.—A white metallic element present in small quantities in most clays. Manganese.—The black and brown oxides of this hard metal are much used to stain slips and bodies, and to colour glazes brown or purple. Marls.—Amorphous deposits of lime, sand, and clay, very coarse in texture. Used in making saggars, drain pipes, and similar appliances. Nickel.—A hard metallic element, the oxides of which are found useful in preparing blacks, greys, and greens. Nitre or Potassium Nitrate, or Saltpetre.—A vitreous and aqueous compound, used in some glazes. Plaster of Paris. (See Gypsum.) Potash.—Potassium carbonate or the leached ashes of plants. Used from earliest times as a powerful alkaline flux. Potash, Bichromate of.—Used for pinks and crystalline effects. Poisonous. Quartz or Quartz Sand.—Like Lynn or silver sand. This mineral is pure silica and free from lime, although the sands may contain some small percentage of iron. Used much like flint for bedding or with alkaline fluxes for the finest glazes. Rutile. Oxide of Titanium.—Used variously to impart a yellow tinge to porcelain, and colour and irregularity to some glazes. Salt.—Sodium chloride. Sometimes used in glazes, but best known in connection with salt glazing. It vaporizes at about 1200° C., forming a silicate or hard, thin skin of glaze over the clay. Silica.—A hard, colourless crystalline element; found pure, as in quartz, or in combination with alumina and alkalies, as in all clays. Present in all glazes. Soda. Sodium Carbonate.—Product of the decomposition of salts with acids. It is a strong alkaline flux and much used in glaze and glass-making. Silver Sand. (See Quartz.) Tin, Oxide of.—Used from the earliest times to impart opacity to glazes. Tincal. (See Borax.) Titanium. (See Rutile.) Whitening. (See Lime.) Zinc, Oxide of.—A white metallic oxide; used to brighten and stabilize glazes and colours.
Potter’s Terms
Bags.—Chimneys or walls of fire bricks built to protect the ware from flame. Baitings.—The feed of fuel during firing. Bat.—Any flat slab of plaster, biscuit, or fire clay. Biscuit.—The fired but unglazed clay. Blowing.—The shattering of the clay shape when biscuiting. Usually due to hurried firing or the sudden access of heat, and the consequent generation of steam. Blunger.—A machine for mixing clay. Bungs.—Piles of filled saggars. Chuck or Chum.—The cone or cap used to support shapes during turning on the lathe. Clamming.—The wet marl, sand, or siftings applied to cracks in the hatches or doors of kilns to retain the heat during firing. Craze.—The minute cracks that appear in a badly fitting glaze. When arrived at by design, as in some Chinese work, it is termed a crackle, but there is then no fissure. Drawing.—Unpacking the kiln after firing. Engobe.—A dip or outer covering of slip; usually applied to inferior bodies to improve their appearance. Fat.—Clays that are sticky or greasy are sometimes termed fat by potters. Fettle.—To touch up, and remove traces of seams, cast lines, etc. Fluxes.—Those materials which by their addition to paste or glaze render them fusible, although they may not always be fusible themselves. Glost.—The glazed ware, usually applied to the glaze in firing, as glost-oven. 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.
Fahrenheit into Centigrade.—Subtract 32, divide by 9, and multiply by 5.
Measures, Weights, etc.
Apothecaries
| 1 grain | = | .0648 gramme. | ||
| 20 grains | = | 1 scruple | = | 1.296 grammes. |
| 3 scruples | = | 1 drachm | = | 3.888 grammes. |
| 8 drachms | = | 1 ounce | = | 31.103 grammes. |
Troy
| 1 grain | = | .0648 gramme. | ||
| 24 grains | = | 1 pennyweight | = | 1.555 grammes. |
| 20 pennyweights | = | 1 troy ounce | = | 31.1035 grammes. |
Avoirdupois
| 16 drams | = | 1 ounce. |
| 16 ounces | = | 1 pound. |
| 14 pounds | = | 1 stone. |
| 28 pounds | = | 1 quarter. |
| 112 pounds | = | 1 hundredweight (cwt.). |
| 20 hundredweight | = | 1 ton (2240 lbs.). |
Capacity (Wet)
| 1 gill | = | 1.42 decilitres. | ||
| 4 gills | = | 1 pint | = | .568 litre. |
| 2 pints | = | 1 quart | = | 1.136 litres. |
| 4 quarts | = | 1 gallon | = | 4.545 litres. |
| 2 gallons | = | 1 peck | = | 9.09 litres. |
| 4 pecks | = | 1 bushel. | ||
| 8 bushels | = | 1 quarter. |
Books of Reference
Technical
Chemistry of Pottery. Langenbeck, Karl.
Chemistry of Pottery. Shaw, Dr. S.
Clays. Occurrences, Properties, and Uses. Ries.
Colouring and Decorating of Ceramic Ware. Brongniart, A.
Ceramic Technology. Binns, C. F.
Notes on the Manufacture of Earthen Ware. Sandeman, E. A.
Notes on Pottery Clays. Fairie, Jas.
Pottery Decoration. Hainbach, R.
Technical and Historical
Leadless Decorative Tiles. Furnival, W. J.
Faience and Mosaic, and other volumes. Furnival, W. J.
Manual
Pottery. Lunn, Richard.
Grand Feu Ceramics. D’oat, Taxile.
The Potter’s Craft. Binns, C. F.
Practical Keramics for Students. Janvier, C. A.
Historical and Artistic
Art of the Old English Potter. Solon, L. V.
Chinese Porcelain. Gulland.
Chinese Porcelain. Monkhouse, Cosmo.
Ceramic Art in Great Britain. Jewitt, L.
History of Pottery and Porcelain. Marryat.
Majolica. Fortnum, C. D. E.
Potters, Their Arts and Crafts. Sparkes and Gandy.
Pottery and Porcelain in the United States (and other volumes). Barber.
Persian Ceramic Art (and other volumes). Wallis, H.
Illustrated catalogue of the Faience of Persia and Near East. Burlington Fine Arts Club.
Appliances and Materials, etc.
| Sold By | ||
| Ball Mills. | Wengers, Ltd. Eng. (Hanley, Stoke on Trent.) | |
| Abbey Engineering Co. 220 Broadway, N. Y. City, U. S. A. | ||
| Biscuit Shapes. | Hirshberg Art Co. Baltimore, Md. | |
| Clays | China and Ball. | Mandle and Sant. East Liverpool, Ohio, U. S. A. |
| China and Modeling. | Stewart & Co. N. Y. City, U. S. A. | |
| Wengers. Hanley, Great Britain. | ||
| Modelling and Stoneware. | Western Stoneware Co. Monmouth, Ill., U. S. A. | |
| Saggar and Stoneware. | W. H. Cutter, Woodbridge, N. J., U. S. A. | |
| Cones. | Wengers, Ltd. Hanley, Eng. | |
| Drackenfeld & Co. Murray St., N. Y. City, U. S. A. | ||
| Professor Ed. Orton. Columbus, Ohio. | ||
| Glazes. | Wengers, Ltd. Hanley, Eng. | |
| Drackenfeld & Co. Murray St., N. Y. City, U. S. A. | ||
| Roessler, Haslacher Chemical Co. William St., N. Y. City, U. S. A. | ||
| Kilns. Gas. | Fletcher, Russell. Warrington, Eng. | |
| Kilns. Gas and Oil. | Bellevue Perfection. Detroit, Mich., U. S. A. | |
| Kilns. Oil. | Caulkins Revelation. Detroit, Mich., U. S. A. | |
| Kilns. Trial. | Wengers. Hanley, Eng. | |
| Lawns and Sieves. | Drackenfeld & Co. 50 Murray St., N. Y. City. | |
| A. Sartorious & Co. Murray St., N. Y. City. | ||
| Wengers. Hanley Staffs, Eng. | ||
| Plaster. | Wengers. Hanley, Eng. | |
| Drackenfeld & Co. N. Y. City. | ||
| Calvin Thompkins. Battery Pl., N. Y. City. | ||
| Quartz, Flint, Felspar. | Wengers, Ltd. Hanley, Eng. | |
| Drackenfeld & Co. Murray St., N. Y. City, U. S. A. | ||
| Golding & Sons. Trenton, N. J., U. S. A. | ||
| Scales. | Wengers. Hanley Staffs, Eng. | |
| Hy. Troemner. Philadelphia, Pa., U. S. A. | ||
| Stilts, etc. | Trenton Stilt & Spur Co. Trenton, N. J., U. S. A. | |
| Wengers. Hanley, Eng. | ||
| U. G. Colours, etc. | Wengers. Eng. | |
| Drackenfeld & Co. N. Y. City, U. S. A. | ||
| Wheels. | Crossley Mfg. Co. Trenton, N. J., U. S. A. | |
| T. S. Nickerson. Newburyport, Mass., U. S. A. |