Imagens da página
PDF
ePub

bined with fixed air, therefore all clays ought to be exposed to the action of the atmosphere for a long time previous to using. Calcareous earth in its common form is limestone or spar, magnesia, &c., which in their pure state are not so easily dissolved as when combined with fixed air. Argillaceous clay or alumina clay forms the basis of common alum; is called argil, and is never found pure; the finest part is extracted from alum, and is not fusible in the strongest heat required for china or earthenware. Argil in its usual state of dryness is capable of absorbing two and a half times its weight of water. Silicious earths found in a stony state abound in flint; the purest are found in crystals and quartz of a pure white; fixed alkalies, vegetables, or minerals are their true solvents. It should be understood that flint and bones, in all instances, are to undergo the process of calcination previous to using.

|

ish stone; 250, Cornish clay; 200, bìue or brown clay; 100, flint; 1, blue calx. 2. 175 parts, Cornish stone; 150, Cornish clay; 90, blue or brown clay; 35, flint; 5, body frit;, blue calx. These bodies are very ductile, and fire at the temperature of the common biscuit oven; each piece of ware should be perfectly dry when placed in the seggars, because they are made a great deal thicker than any other kind. Setters also should be used at the bottom of each piece, and ground flint applied, but not sand, for the placing or seating; the body, when burnt, quite vitrified, and the pieces of ware strong and heavy, ringing remarkably shrill.

PRINTED EARTHENWARE BODY, Superior.-3 parts, blue clay; 1, black or brown clay; 2, Cornish clay; 14, flint;, Cornish stone.

Common.-2 parts, blue clay; 2, brown or black clay; 1, Cornish clay; 12, flint.

CREAM-COLOURED BODY, Superior.-13 part, blue clay; 1, brown clay; 1, black clay; 1, Cornish clay; 1, flint;

Common.-1 part, blue clay;

1, brown clay; 1, black clay; 1, flint.

LILAC PORCELAIN BODY.-200 parts, bones; 115, Cornish clay; 25, blue clay; 20, flint; 15, chalk; 10, Cornish stone; 14, blue calx.

FIRING.-Articles formed of one of the bodies are first moderately burnt in earthen pots, to receive a certain degree of compactness, and to be ready for, Cornish stone. glazing. The glaze consists of an easily melted mixture of some species of earths, which, when fused together, produce a crystalline or vitreous mass, and which after cooling is very finely ground and suspended in a sufficient quantity of water. Into this fluid the rough ware is dipped, by which the glazing matter is deposited uniformly on every part of its surface. After drying, each article is thoroughly baked or fired in the violent heat of the porcelain furnace. It is usual to decorate porcelain by paintings, for which purpose enamels or pastes, coloured by metallic oxides, are used, so easy of fusion as to run in a heat less intense than that in which the glazing

[blocks in formation]

DRAB BODY.-24 parts, argilla ecus marl; 48, Cornish stone; 24, blue clay; 10, bones; 1, calcined nickel.

COMMON BROWN, or COTTAGE BODY.— 20 parts, red or brown clay; 8, Cornish clay; 4, blue clay; 2, flint.

FAWN, or DRAB BODY.-40 parts, marl; 4, Cornish clay; 1, flint.

CALCEDONY BODY.-32 parts, yellow clay; 10, Cornish clay; 4, flint.

BROWN BODY.-50 parts, red clay; 7, common clay; 1, manganese; 1, flint.

JASPER BODY.-10 parts, chalk; 10, blue clay; 5, bones; 2, flint; 14 blue calx. All the materials should be ground together, as much depends on the different articles being well united, which adds greatly to its fineness in

colour and lustre. It fires at the temperature of earthenware ovens.

SUPERIOR WHITE BODY.-50 parts, chalk; 50, blue clay; 25, bones; 10 flint. This body is of the same consistency, and requires the same temperature as the jasper body. It is perfectly adapted also for the purpose of figures in bas-relief, and other ornamental work.

STONE BODY. -480 parts, Cornish stone; 250, blue and brown clay; 240 Cornish clay; 10, glass; 1, blue calx. This body will be sufficiently vitrified at the temperature of the earthenware biscuit oven, and is adapted for the purpose of manufacturing jugs, mugs, and so on; it is requisite to place rings on each piece of ware, in order to keep them from being crooked when burnt in the oven; in all other respects to be treated as earthenware bodies.

STONE MORTAR BODY.-480 parts, Cornish stone; 250, blue and brown clay; 240, Cornish clay; 10, glass; principally used for making stone mortars, and when burnt of a yellowish white, absolutely vitrified, exceedingly strong, very durable, and produces a clear bell sound.

BLACK EGYPTIAN BODY.-235 parts, blue clay; 225, calcined ochre; 45, manganese; 15, Cornish clay; the materials must be accurately examined on account of the manganese, which ought to be free from lime or other calcareous earth; the pieces of ware when manufactured are very apt to crack, because of the sudden transition from heat to cold, provided above a certain proportion of lime is contained in the manganese. This kind of earthenware requires only once burning, after which it is scoured with fine sand, and then a small quantity of oil rubbed over it.

RING BODY.-150 parts, blue clay; 100, Cornish stone; 100, bones ; 52, plaster. Used for making rings and setters, for placing porcelain and ironstone; the porcelain clay which gets dirty or injured by working may be used for the same purpose, in the proportion of two of the former to one of the latter.

SAUCER MOULD BODY. -10 parts, flint; 4, blue clay; 2, Cornish clay; 1, black clay. Prepared for the sole purpose of making moulds, principally those of saucers; moulds made in this way are preferable, and considerably more durable than those which are made of plaster; the contraction of this clay in burning is inconsiderable.

FAWN POROUS BODY.-40 parts, argillaceous clays; 4, blue clay; 2, flint. This body makes porous wine and butter coolers, and water bottles, on the principle of absorption and evaporation. The articles are generally ornamented with various coloured clays, according to the five following recipes; they should be kept in the wet clay state, at the time of being painted, otherwise the different colours laid upon them will not sufficiently adhere, but are liable to chip and peel off when burnt. moderate degree of heat must be applied, as too great a temperature will cause the body to be too dense, and prevent absorption; it will therefore be necessary to fire such articles in the easy parts of an earthenware biscuit oven.

A

Silicious and Argillaceous Clays. These clays are for the purpose of painting porous coolers and bottles in the Mosaic style, and are equally applicable to the ornamenting of china and earthenware; the mixtures must be well ground, for their fineness has a great tendency to equalize the contraction and expansion of bodies in firing.

WHITE CLAY.-4 parts, blue clay; 2, Cornish clay; 2, flint; 1, Cornish stone. BLUE CLAY.-30 parts, white clay; 1, blue calx.

BLACK CLAY.-4 parts, black Egyptian clay; 1, white clay; 1, blue clay.

ORANGE CLAY.-4 parts, yellow clay; 2, Cornish clay; 1, flint;, Cornish stone.

GREEN CLAY.-12 parts, white clay; 1, nickel; 4, blue clay.

Glazes. - PORCELAIN GLAZE.-40 parts, Cornish stone; 45, red-lead; 38, borax; 321, flint; 221, flint glass; 13, crystal of soda; 5, oxide of tin; 1, enamel blue. The particles are made small and well mixed together, then calcined

through a fine lawn; the former glaze is of the finest texture, and will require rather a thinner coating when dipped than those of common glazes. Fire in seggars, either washed with common glaze, or a mixture of lime and slip without flint.

in the coolest part of the glazing oven, | These glazes, when ground, to be sifted in seggars thickly lined with flint; care must be observed that the frit is not too highly calcined, or brought into a high state of vitrification; if so, it will render it difficult to grind, and injure its good qualities in dipping. The frit likewise if too finely ground will cause the glaze to be uneven on the surface of the ware; if any inconvenience of this nature arises, by adding a solution of potash in hot water, that defect will be instantly obviated.

IRONSTONE GLAZE.-36 parts, Cornish stone; 30, borax ; 20, flint; 15, redlead; 6, crystallized soda; 5, oxide of tia;, blue calx. With the above frit is to be added 15 parts, white-lead; 10, Cornish stone; 10, flint; when ground together, the composition is ready for use; should the glaze prove too thin for dipping, add a small quantity of muriatic acid.

BODY FRIT.-60 parts, Cornish stone; 40, flint; 30, crystallized soda; 8, oxide of tin; 10, borax. This frit is used in small quantities, in china and ironstone bodies.

FRIT FOR GLAZES.-1. 40 parts, Cornish stone; 36, flint glass; 20, red-lead; 20, flint; 15, potash; 10, white-lead; 3, oxide of tin. This frit is intended to be used in glazes, in lieu of those which contain a large proportion of borax; therefore, by substituting it when the price of that article is high, will, of course, be advantageous, and the texture of the glaze will still be good and admissible.

2. 36 parts, Cornish stone; 30, redlead; 20, flint; 20, borax; 15, crystal of soda; 5, oxide of tin. These two frits may be calcined in the easy part of the glazing oven, in seggars lined with flint; particular care should be observed that they are clean chipped, and free from pieces of seggars, or any dirty substance. EARTHENWARE PRINTED GLAZE, Superior.-90 parts, white-lead; 35, Coraish stone; 20, flint glass; 20, flint; 60, frit (for glazes, 2); , blue calx.

Common.-85 parts, white-lead; 35, Cornish stone; 22, flint; 15, flint glass; 24 frit (for glazes, 2); †, blue calx.

COMMON PRINTED GLAZE.-90 parts, white-lead; 45, Cornish stone; 22, flint; 20, flint glass; 4, blue calx. To this, after being properly ground and sifted, add 1 lb. of common salt and lb. of borax, which forms a smear or flow, as it is generally termed, but must not be put into the glaze until the blue stain is perfectly incorporated with it; the ware dipped therein must be placed in seggars washed with glaze.

WHITE EARTHENWARE GLAZE.-35 parts, Cornish stone; 20, borax; 10, crystal of soda; 20, red-lead;, blue calx. Calcine and then pulverize coarsely, and grind with 20 lbs. whitelead, 10 lbs. Cornish stone, and 5 lbs. flint.

BLUE AND GREEN EDGE GLAZE.-72 parts, litharge; 36, Cornish stone; 20, flint glass; 17, flint; 12, frit (for glazes, 2); }, blue calx. The blue and green edged ware when dipped in this glaze should be perfectly dry previous to being placed in the seggars, and the green edge should be seated in the coolest part of the glazing oven.

[ocr errors]

CREAM-COLOUR GLAZE, Superior.—85 parts, white-lead; 40, Cornish stone; 22, flint; 16, flint glass; 8, frit (for glazes, 2). Common. 75 parts, litharge; 40, Cornish stone; 23, flint; 10, flint glass. CRYSTAL GLAZE.-105 parts, Cornish stone; 90, borax; 60, flint; 50, red-lead 12, crystal of soda; 10, oxide of tin; 4, blue calx. This glaze produces very superior white earthenware, and, for the purpose of enamelling, the colours, lustres, and burnished gold appear to considerable advantage; it is also adapted for ironstone, and makes superior blue printed earthenware; it has a singularly striking effect on printed brown and mulberry. When used for dipping it must be considerably diluted, and requires but

little shaking from the hand of the operator. It requires the heat of a china glazing oven, but to answer the earthenware oven a small addition of white-lead must be made, according to the temperature of firing. The materials must be mixed and calcined, and the ware fired in lime and slip seggars, well washed.

BROWN COTTAGE GLAZE.-60 parts, litharge; 32, flint; 8, brown slip. This and the two following glazes require using about the same consistency as the cream-colour glaze, and will stand the highest temperature of heat in a common glazing oven.

CALCEDONY GLAZE. 65 parts, litharge; 40, Cornish stone; 20, flint; 6, frit (for glazes, 2).

DRAB GLAZE.70 parts, litharge; 30, flint; 25, Cornish stone; 10, drab slip.

BLUE GLAZE. - 50 parts, flint; 30, borax; 22, red-lead; 10, Cornish stone; 6, crystallized soda; 6, oxide of tin; 3, blue calx. In preparing this glaze follow the same directions as for porcelain glaze. GREEN GLAZE.-3 parts, blue vitriol, calcined; 1, flint glass; 1, flint. When ground, take 4 quarts of this mixture to 30 quarts of the following mixture, ground:-35 parts, litharge, 20, flint; 10, Cornish stone; 10, frit, for glazes. This glaze is sufficiently fired in the coolest part of the glazing oven. Particular attention should be observed as to the proper wash used for the seggars, for much depends on that simple process. The brightness and lustre of the glaze will be secured by adopting the following wash :-5 parts of the solution of quicklime; 1, of clay slip, free from the least particle of flint, and applied about the thickness of common glaze.

YELLOW GLAZE. 95 parts, whitelead; 35, flint glass; 20, flint; 14, oxide of yellow; 10, Cornish stone; 16, frit, for glazes. The oxide of yellow must be very finely ground, and the other materials ground and sifted before the oxide of yellow is added. It would be as well first to mix the yellow and the frit together, then let them be passed through a lawn into a vessel containing the other ingredients; by this means the materials

will be better incorporated; use it about the same thickness as cream-coloured glaze, and treat it the same. It will fire almost in any part of the oven, in seggars either washed with glaze or mixture of lime and slip.

ALKALINE GLAZE.-30 parts, borax; 30, flint; 18, Cornish stone; 2, oxide of tin. The materials must be calcined, and particular caution observed in the course of chipping from the seggars, that not the least particle of any colouring matter be mixed with it, for it is very susceptible of being materially injured in its colour; when ground, a small quantity of muriatic or nitrous acid should be added, and at the same time quickly stirred about, and the motion continued for some time, in order to prevent it setting at the bottom of the vessel; in all other respects treated the same as common glazes, except with regard to dipping, in which case it must be used very thin.

Colours under Glaze, with the exception of the green, should be mixed together and calcined in a reverberatory furnace or glazing oven, in segga hillers, or dishes lined with flint; then spread on the mixture about an inch in thickness, observing that the hiller or dish have a sufficient access of air allowed, to prevent the metals from reviving again in their metallic state: the green ingredients only require grinding.

NAPLES YELLOW UNDER GLAZE.-12 parts, white-lead; 2, diaphoretic antimony; 1, crude sal ammoniac;, alum. Mix intimately, calcine in a crucible, over a slow fire, for the space of three hours, stirring it nearly the whole of the time, when the mass will be found of a beautiful yellow or gold colour.

LINING BROWN UNDER GLAZE. 7 parts, glass of antimony; 3, raw litharge; 2, manganese; 1, nitre; 1, blue calx.

PAINTING BROWN UNDER GLAZE.-5 parts, glass of antimony; 5, raw litharge; 2, manganese;, blue calx.

ORANGE UNDER GLAZE.-6 parts, raw litharge; 4, crude antimony; 2, crocusmartis; 1, oxide of tin.

YELLOW UNDER GLAZE.-4 parɩs, raw

[blocks in formation]

GREEN UNDER GLAZE. 12 parts, oxide of yellow; 4, white enamel; 2, frit (for glazes prepared without the oxide of tin); 14, blue calx.

PRINTED BROWN UNDER GLAZE.-5 parts, raw litharge; 5, crude antimony; 24, manganese; 1, blue calx.

PRINTED BLACK UNDER GLAZE.-3 parts, red-lead; 14, antimony;, manganese. After these ingredients have been calcined, add the following, and calcine again: 2 parts, blue calx; 4, oxide of tin. This black under glaze, in the last stage of preparation, must be calcined in the highest heat of a biscuit oven, and crystal glaze is the most suitable to it. The ware must be fired in an easy part of the glazing oven; the brown calcined in the usual way, and dipped in the common printed glaze.

PRINTED MULBERRY UNDER GLAZE. -4 parts, manganese; 2, blue calx; 1, nitre;, borax. Calcine this colour in the usual way, either in a dish or seggar hiller, and after the mixture is spread on the dish or hiller, a small quantity of pounded nitre should be scattered thinly over, and when calcined, add 2 parts of flint glass; 1, flint; then grind all the ingredients up together for use.

GREEN FOR EDGING UNDER GLAZE.3 parts, oxide of copper; 3, flint glass; 2, flint; 2, oxide of tin; 1, enamel blue. Grind these ingredients together, after which add 8 quarts of earthenware printed glaze, and 4 quarts of creamcolour glaze, mix well together, and sift them through a fine lawn. Lay this green on the ware after it is dipped, and fire it in the coolest part of the glazing

[merged small][ocr errors][merged small]

| oxide of tin, when mixed with the blue calx, for that metal and arsenic are both prejudicial to its colour.

2 parts,

STRONG PRINTING BLUE. blue calx; 3, blue printed flux. WEAK PRINTING BLUE.-1 part, blue calx; 4, blue printed flux (2).

Printing Oil for Pottery.-1. 1 quart linseed oil, 1 pint rape oil, 2 oz. balsam capivi, 1 oz. pitch, oz. amber oil, oz. white-lead. 2. 1 quart linseed oil, pint rape oil, pint common tar, 1 oz. balsam sulphur, 1 oz. balsam capivi. The linseed oil should be boiled for some time alone, then add the rape oil and the balsam capivi, allow the boiling to be continued until it begins to approach the proper consistency, and add the remain ing ingredients. The mixture should be allowed to cool a short time, after which the whole mass may be boiled slowly until it has assumed the proper thickness; the vessel must be generally covered during the process, and the sulphur previously to being mixed with the oil should be perfectly pulverized, as by that means it is less liable to curdle the oil.

Stains for Pottery. In pre paring these stains the ingredients must be ground remarkably fine, and then so perfectly dried as not to leave the least humidity, after which they must be ground again with oil prepared for the purpose, composed of 2 parts of balsam of sulphur, 1 part of amber oil, and as much turpentine as will render them of a proper consistency; they may then be used with ease for painting various devices on biscuit ware.

BLUE STAIN.-5 parts, blue calx; 2, frit, for glazes, without oxide of tin; 1, flint glass; 1, enamel blue.

YELLOW STAIN.-3 parts, yellow under glaze; 1, frit, for glazes;, chromate of iron.

GREEN STAIN.-3 parts, blue stain; 1, yellow stain;, enamel blue green.

Gold Flux.-11 parts, borax; 5, litharge; 1, oxide of silver. In these enamel fluxes the materials are to be made very fine, particularly the flint, and mixed well together, so that the particles may more easily concrete when in a state of fusion; then calcined in an

« AnteriorContinuar »