JUDGING VINTAGE DINNERWARE©

If you prefer to begin with THE STORY OF DINNERWARE, click on https://dearfriend.buzz/category/dinnerware/?order=asc

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How old is the dinnerware?

The age of dinnerware provides a clue about the risk of lead poisoning.

Dishes produced before 1971 are more likely to contain dangerous levels of lead  even though many dishes produced before 1971 do not contain lead.

If you can identify the manufacturer and pattern name, you can contact them to learn more about the glaze used and the possibility of lead.

Even if  dishes originally did not leach lead—but are now chipped or scratched by steak knives—or if the pattern has begun to wear off, using them is not worth the health risk. The FDA recommends using a home test kit to determine lead content.

Most suspect for lead are:  folk pottery, hand-crafted dishes and patterns made prior to 1971 when the FDA set standards for lead usage in dinnerware.

Is the glaze in good condition?

If glaze is crazed or crackled, the dinnerware might have been stored in a hot attic or damp cellar. Temperature and humidity affect the contraction and expansion of earthenware clay bodies and glazes which in turn causes crazing and crackling. Crazes, cracks and chips in earthenware may hold bacteria and should not be used for food.

How long does dinnerware last?

All dishes break, yet many of us use dishes belonging to our grandparents. Good care, minimal usage and excellent storage keeps ceramic dinnerware looking good for several generations— although it’s advisable to test old dinnerware for lead. Daily usage and constant swishing of dishwasher detergents takes a toll on the glaze and pattern decorations of ceramic dinnerware.

Do you know the generic name of the clay?

Each kind of generic clay imparts characteristics of delicacy and/or sturdiness which affects purity and durability. Most dinnerware has a manufacturer’s logo stamped and fired on the bottom of each piece. So if you’re not sure of the generic name of the clay— (experience has taught me not to trust the seller’s opinion),check the manufacturer’s website.

Where was the dinnerware made?

Most developed nations have mass-produced and exported reliable dinnerware for the last 200 years. However, there is possible danger of lead leaching into food from contemporary folk pottery dishes from developing nations. It’s suggested these wares be used only as decoration.

Is the dinnerware well-finished?

All edges of ceramic dishes, including foot rims, must be smooth and there should be no visible mold marks on a top surface. Spouts, handles and finials must not look ‘added-on’, they should appear seamless.

Is the pattern a decal or hand-painted?

Just because a pattern is hand-painted, ‘sloppy’ is unacceptable. All patterns, whether transfer or decal, must appear seamless. If an applied pattern shows excessive signs of wear, pass.

 Pat Breen: EYEWITNESS TO QUALITY

My next post is :  THE STORY OF COOKWARE

HOW DO YOU KNOW IF THE QUALITY OF CERAMIC DINNERWARE IS GOOD?©

 IDENTIFY THE GENERIC NAME OF THE CLAY:

Never fall in love with a dinnerware pattern without learning the generic name of the clay. Is it earthenware, stoneware, bone china or porcelain? If dinnerware is decorated, determine the type of glaze: underglaze—overglaze, and be sure the glaze is lead free. 

This information should be available in the retail store but if your answers are unsatisfactory, contact the manufacturer. Any ceramic dishes with metallic decoration, should NOT be used in a microwave oven or dishwasher.

 PRODUCTION METHODS:

You can’t simply ‘look’ at dinnerware shapes and know what kind of mold was used to make each piece— because all finished pieces must have uniform wall thickness. All flat surfaces must be smooth—without excesses of glaze or pin-point holes in the glaze. Pin-point markings beneath each plate are the result of stacking pins used to separate dishes during firing and are unavoidable.

Visible mold marks and visible joinings as cup handles or
rough edges anywhere—including foot rims—indicate
care was not taken to perfect each piece in its greenware
or bisque state. This is sloppy ‘craftsmanship’.

Determine the care with which patterns have been applied.
If a decal, seams must be invisible where the ends of each
decal are joined. If hand-painted, execution must be excellent.

FINALLY:

Examine the following elements to judge if production quality is good.

 GENERIC NAME OF THE CLAY:

The generic name of each clay provides direction
for the care and durability of dinnerware.

All generic clay as earthenware, stoneware, porcelain and bone china contains elements that impart characteristics of delicacy and/or sturdiness and also affect purity, firing temperature and durability.

Several catalogs recently identified dinnerware made of ‘chip-resistant white clay’; a specious phrase to create an impression of durability and not the name of a clay.

SURFACES:

All glazed ceramic surfaces must be unblemished and void of warping, porosity, and pit marks. The thickness of clay must be uniform. All ceramic products having handles, spouts or any part molded separately and ‘pasted-on‘, must have no indication they were ‘added-on’. Finished products must appear seamless.

GLAZES:

Crazing and crackling are fine lines in a glaze usually caused by non-fitting glazes or a wrong firing temperature or they may be deliberately forced by a factory to sell as ‘instant-antiques’. Extremes of temperature causes crazing and crackling in glazed ceramics because clay and glaze contract and expand at different rates. This may happen if dishes are stored in a cellar or attic. Request assurance that any lead in the glaze of the dishes you like, meets consumer standards established by the FDA.

MOLD MARKINGS:  

Mold marks must not be visible on dinnerware. These should be removed in the greenware stage prior to firing. Marks from small stacking-pins used to separate wares during firing are hard to avoid but should be present only on the bottom of each piece.

FOOT RIMS:  

‘Foot rims’, the ridge upon which every piece of dinnerware ‘sits’, must be smooth. Manufacturers may grind them smooth or they may be glazed to avoid damaging the table top as well as tops of other plates if dishes are stacked upon each other.

HAND PAINTED DESIGNS:  

Insist upon excellence. The beauty of hand work is the lack of perfect uniformity, not the lack of standards. Hand painted dinnerware will be more expensive, as Maiolica or Delft.

I chose hand-painted Italian maiolica dinner plates in a
NYC department store and wanted twelve. After examining
several dozen, only nine were acceptable. 
The hand-painting
was sloppy and careless— and both sales 
and management
personnel rationalized the poor quality saying, 
“but they’re
hand-painted”.

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Yes, badly hand-painted. The plates should never have been
shipped by the factory —and should have been rejected by the
store—and I should not have been dismissed with such a shoddy
excuse for such shoddy merchandise.  The plates and the store
were poor ‘quality’
.

DECALS OR TRANSFER DESIGNS:  

All designs must appear seamless. Just as you would not purchase clothing
if a pattern did not meet at the seams, this standard applies to transfers or decals on dinnerware.

CUPS AND SAUCERS:  

When I helped couples select dinnerware in the Gift Gallery, grooms were most concerned for the comfort of the cup handle.  And if a teaspoon easily slid from the rim of the saucer into the cup well as the cup was lifted—the pattern was immediately rejected.

METALLIC TRIM:

Metallic decorations are the last thing ‘fired’ in a kiln because they require a low temperature. Metallic trim is also ‘soft’ and eventually wears away so metallic trimmed dishes should never be washed in a dishwasher: the combination of swirling hot water and detergent is too abrasive.

Nor should metallic trimmed dishes be used in a microwave oven
because microwaves cannot pass through metal: they damage the
oven if reflected back into the magnetron. 

Pat Breen: EYEWITNESS TO QUALITY

My next post is:  JUDGING VINTAGE CERAMIC DINNERWARE

DISHES: FROM CUPS TO CASSEROLES©

 

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DINNERWARE

SHAPES AND EDGES:

Every culture has produced ceramic dinner ware in shapes and sizes to enhance special culinary skills. Unusual shapes include flowers, shells, cabbages, asparagus, corn and even playing cards. Currently, round dishes prevail, although square and rectangular are increasingly popular.

RIMMED PLATES have flat outer rims higher than the center of the plate. Rims serve as a picture frame for plated foods.
COUPE PLATES are gently sloped and have no rim.
EDGES of any shape may be plain, ornate, or fluted.

PLACE SETTINGS:

In the United States, a  five-piece place setting of dinnerware includes one cup, one saucer, saucer, one bread and butter, one salad/dessert plate and one dinner plate.

Some manufacturers include a soup/cereal bowl instead of a bread and butter plate. Casual patterns may include a mug instead of a cup and saucer, which makes it a four-piece place setting.

In countries where coffee or tea are not traditionally served
with or after a meal, matching cups and saucers are not part
of a place setting. When a pattern is sold as open stock, an
advantage is that each place setting piece and serving piece
can be purchased separately.

CUPS:

Traditional shapes for coffee and tea cups are derived from their indigenous origin. Non-traditional shapes are also made by quality dinnerware manufacturers.
COFFEE CUPS:               straight sided in sizes up to lattѐ.
TEA CUPS:                       low and wide with a rounded profile.
AFTER DINNER CUPS: smaller than regular sizes.
DEMITASSE CUPS:        very small.

PLATES: 

BREAD AND BUTTER…….6 ½ ” – 6 ¾”also hors d’ouvres or side plates.
SALAD OR DESSERT.…….7 ½” – 8 ½”
LUNCHEON.……………….9″
DINNER……………………10½” – 10 ¾”
BUFFET…………………….12″

SOUP BOWLS:

CONSOMME CUPS:           ‘cup sized bowl’  with or without handles.
SOUP/CEREAL BOWLS:    6 – 8” bowl without handles.
SOUP/PASTA PLATES:      8 – 10″ shallow bowl usually  rimmed.
CREAM SOUP BOWLS:      5 – 7” bowl with double handles and saucer.   Double handles are more expensive than single handled bowls because it’s difficult to achieve two ‘perfect’ handles.

SERVING DISHES:

Platters of all sizes and shapes • Vegetable dishes with or without covers • Casseroles • Tureens • Gravy boats • Relish dishes • Salad bowls • Creamers and sugar bowls • Salt & Pepper shakers …..and for some patterns, the list goes on and on and on…………

Left-over platters and casseroles from sets of broken dinnerware are reasons to forego matching serving dishes. Tables can look more interesting with enamel, steel, silver or oven-to-table serving dishes.

STARTER SETS:

Traditionally, 20 piece starter sets are four 5-piece place settings. Contemporary and casual patterns may include soup bowls instead of bread and butter plates.

16 piece starter sets may include four each of mugs, soup/cereal bowls, salad/dessert plates, and dinner plates.

SERVICE SETS:

Dinnerware manufacturers usually offer set savings when purchasing service for 8 or 12. Sets may include serving pieces which are considerably more expensive than place-setting pieces. If you subtract the retail value of serving pieces, savings may be negligible—and you may own serving dishes you don’t want or need.

OPEN STOCK:

Open stock means any single piece of a pattern is available to consumers. When a pattern is sold only as a set, single pieces might not be available. But ceramic dishes break. It’s said cups break first but breakage is not reserved for cups; we also break salad plates, soup bowls, saucers, etc.

While a pattern remains open-stock, any piece may be added or replaced.  It’s also an opportunity to add unusual sizes and shapes for your favorite foods. Patterns are usually produced as long as they remain popular.

An executive from a prestigious dinnerware company
couldn’t understand why brides felt compelled to
choose formal dinnerware,” it’s incongruous for the
way most of them will entertain”.

Company dinnerware does not have to be delicate or formal bone china or porcelain. Julia Child used Arabia of Finland’s robust dark brown RUSKA stoneware to plate French cuisine.

 Pat Breen: EYEWITNESS TO QUALITY

My next post is:  JUDGING THE QUALITY OF CERAMIC DINNERWAREnull

DECORATING CERAMIC DINNERWARE©

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DECORATIONS:
APPLIED TO GREENWARE

The following relief designs can be hand-crafted by removing or adding clay motifs to the surface of greenware (dry clay shapes not yet fired) before firing and glazing. Mass-produced relief  designs are created as part of the mold.
 •  Sgraffito: Designs are incised or scratched into clay—the origin of ‘graffiti’.
  Raised design: Clay is applied to greenware as if decorating a cake.
•   Pierced design: Perforations made in greenware before firing to a bisque stage.

DECORATIONS:
APPLIED TO BISQUE OR GLOSTWARE:

Transfer printing:

Transfers were the first successful mechanization of uniform decorations for dinnerware. Drawings are engraved or etched on a copper plate. The design is printed on tissue paper with oil-based color and rubbed or transferred— on bisque wares and fired. Colors are transferred one at a time.

Decalcomania:

Lithograph designs are screened in full color onto film-coated paper with china paints. Decals are soaked in water allowing the design to ‘slide’ onto bisque or glost wares.

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Skilled workers press each soaked decal in place seamlessly on each shape and hand sponges it to make sure the application is perfect before firing. Paper burns off in the firing.

Hand painting:

This is time consuming and requires skilled artists with standards of excellence.

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Pigments are mixed with ‘fat oil’ and aniseed for consistency. Some designs require several firings because different colored glazes require different temperatures. Designs may be embellished with enamel colors and/or metallic paints but must be fired again.

SEQUENCE OF GLAZES AND DECORATIONS:         

After clay shapes are dry, they’re ‘cooked’ in a kiln, glazed and fired. If decorated with a decal or hand painted pattern, they’re fired again. Clay bodies and glazes must ‘fit’ ’ each clay body. This means shrinkage and firing temperatures for both clay and glaze are compatible.

Unlike earthenware, porcelain, bone china and stoneware are high-fire clays that vitrify in the bisque stage and require glaze only to provide a glassy surface for cutting and avoid stains from food. Although these clays can be dried, glazed, decorated and fired in a single sequence, some factories prefer to first apply and fire a transparent glaze (glost) prior to decorations for easier application of patterns. During a second firing,   a hand-painted or decal decoration penetrates through the fired glaze to become very durable.

Glazed and fired dinnerware without decoration are called blanks.

Blanks are marketed as white dinnerware or they are decorated with glazes, decals and/or hand-painted patterns. Labor costs increase each time a clay body is handled for shaping, glazing, decoration and firing which makes complex designs more expensive to produce.

White dinnerware is and should be cheaper because production and labor costs are less. This changes the price; not the quality.

Many couples shopping in the Gift Gallery preferred the simplicity
and versatility of white dinnerware. They were puzzled because
plain white dishes were much less expensive than patterned dishes.
They’d ask, “But are they good?

I’d select different patterns at different prices in their preferred
brand and shape and place the bread and butter plates upside-down
so the bottoms of each plate were identical.

Asking the couple to select the ‘best’ brought quizzical smiles.
They realized quality was identical:
more costly plates are more costly decorated.

Metallics, a final touch:

Because metallic ornamentation has a low melting point and must be fired at a low temperature, it’s applied after all other ornamentation has been fired. Specialists apply metallic edges, bands and borders to circular ceramic shapes placed on a whirler        —which they rotate with one hand as they hold a paint brush loaded with metallic pigments steady with their other hand.

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As if by magic, the artist, the whirler, the brush, the paint and plates add up to painted bands of perfection! After cooling, these designs require hand-burnishing with agate or other materials to enhance the metallic shine.

 Pat Breen: EYEWITNESS TO QUALITY

My next post is:  DISHES: FROM CUPS TO CASSEROLES

GLAZING CERAMIC DINNERWARE©

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Some clays can be dried, glazed, decorated and fired in a single sequence but many quality factories prefer to first apply and fire a transparent glaze (glost) prior to decorations for easier application of patterns. During a second firing, a hand-painted or decal decoration penetrates the glaze to become very durable.

If lead oxides are part of a glaze formula, they will leach
into food unless the firing temperature is sufficiently
high to burn out traces of lead.

The composition and firing temperature of each glaze must ‘fit’ each clay body because clay shrinks as it dries to the greenware state —and shrinks again an average of 12% or more when fired in a kiln.   Glazes must shrink at a comparable rate.                          

                                                   

Different colors or applied ornamentation may require firing at different temperatures so each piece may be fired several times before completion. Glazes seal the porosity of clay and protect decals or painted designs from wearing away. Labor costs increase every time a ceramic body is handled for decoration or firing.

EARTHENWARE GLAZES:

Opaque tin-oxide glazes, usually white, were applied to earthenware bisque to cover over the color of the clay —and then hand painted with colorful designs over the glaze. Well known indigenous names for opaque tin-oxide glazes include:

 FAIENCE:

Tin glazed earthenware has been made since 1100 in Faenza, Italy where even the street signs  are ceramic. When the French began to make similar wares, they named  it faience. It is still made in the oldest pottery factory in St. Clement, France.

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MAIOLICA:

Historians trace tin glazes and design influences on ceramics to the Moors who brought these techniques to Spain. By the 15th Century, tin-glazed pottery from the island of Majorca, made in Arabic tradition, inspired Italian ceramic wares named maiolica.

The name continues for soft-fired Italian earthenware covered with opaque glazes containing tin oxides which masque the color of the clay and allow for strong colors in a range of decorative motifs including original Renaissance pictorials painted by by hand in an earthy, robust style.

MAJOLICA:

Originated by Minton in the 1860’s, English earthenware with high relief designs and covered with brilliant colored shiny lead glazes is majolica (with a j)— borrowed from—but not to be confused with maiolica.

DELFT:  

Tin glazed earthenware made by Italian potters in the Netherlands mid-16th Century is delft.  In the production of Delft, an opaque white glaze is applied to earthenware and overglazed with a hand painted design, commonly monochromatic blue, inspired by imports of blue and white Ming porcelain.
These Dutch ceramics remain popular.

 CAVEAT:

Dishes used for preparing or eating food must be LEAD FREE.

For centuries, lead has been used in ceramic glazes to help glaze particles melt blemish free. Glazes must be formulated and fired at temperatures sufficiently high to destroy traces of lead.

Improperly fired, lead can leach into food. We’ve known for decades that severe  health problems have arisen from lead in paint, the same problem that arises from dishes that leach lead into our food.

Most domestic manufacturers have stopped using lead in their glazes. Dishes made before 1971, but not all,  are more likely to contain dangerous levels of lead although it is rarely found in plain white dishes.

The FDA recommends home test kits to determine if dishes are leaching lead. They’re available in most hardware stores–and detect only the presence of lead—not the amount.

Before buying ceramic dinnerware,
ask about lead content and require proof the dishes are safe.

 Pat Breen: EYEWITNESS TO QUALITY

My next post:   DECORATING CERAMIC DINNERWARE

FIRING CERAMIC DINNERWARE©

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FIRING CERAMIC DINNERWARE

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Clay shapes are fired in a kiln to become
stone-like, durable and functional
.

Clay, hardened by heat– is called ceramic.

Generally, the purer and finer the clay, the higher the firing temperature—which explains the strength and durability of some dinnerware that looks fragile.

Once fired, the composition of clay cannot be reversed.  Depending upon the clay and the decoration, ceramic dinnerware may go through several firings at different stages of production.

Because kilns require intense heat, dinnerware factories were usually located near forests until wood heat was replaced by coal, and much later gas, then electricity.

1st FIRING: CHANGING GREENWARE to BISQUE:   

Clay shapes— dried but not yet fired, are greenware.  Firebrick separates stacked  and loaded greenware on a moving framework which passes slowly through a kiln for a first firing to the bisque stage.  Bisque is the name of porous clay shapes that are fired —but not glazed.

In the bisque stage, foot rims and edges of all shapes can be ground and polished to eliminate roughness prior to being glazed—or they are tumbled with polishing pellets for extra smoothness. Each piece is examined before a transparent glaze is applied and fired  to the ‘glost’ stage.

 2nd FIRING: CHANGING BISQUE to GLOST:  

After greenware is dipped or sprayed with a transparent glaze, the shapes are dried and stacked on refractory firebrick to separate each piece as they move slowly through controlled zones of heating and final cooling temperatures, usually within a tunnel kiln. 

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 BISQUE shapes, now GLOST , await further glazes and decoration.

Tunnel kilns illustrate how capital and real estate intensive is the dinnerware industry. I visited several factories having tracks in the floor to guide loads of ceramic shapes in various stages of production—including their journey through a tunnel kiln.

Uniform thickness of clay is critical to assure successful firing; uneven clay bodies crack or explode when fired.  Firing temperatures must be lower than the deforming or slumping temperature for each variety of clay and they vary greatly for different clays and glazes. Different colors and applied ornamentation may require firing at different temperatures and wares may be fired several times before completion.  Glazes seal the porosity of clay and protect decals or painted designs from wearing away.

Additional firings depend upon the glazes, patterns and decorations required for each pattern.  Labor costs increase every time a ceramic body is handled for decoration or firing. 

Pat Breen: EYEWITNESS TO QUALITY

My next post is: GLAZING CERAMIC DINNERWARE

CERAMIC DINNERWARE PRODUCTION©

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 PREPARATION OF CLAYS:

Artisan producers purchase clay in lump, powder or plastic form. Wet clays are wedged,  meaning the lumps are banged together to eliminate air and to even the texture, or they’re kneaded, which consistently brings all of the clay to the surface to be compressed and assure all air is eliminated.

Mass-producers of dinnerware purchase clays in a dry form.  Each factory develops their own formulae but generally, all coarse materials are first ground very fine in a ball mill and blended with water in a blunger to control plasticity, grain size and moisture.

The result is SLIP, a clay and water suspension used for molding hollow shapes. Slip is passed over electromagnets to remove particles of iron and other impurities.

 ARTISAN SHAPING OF CLAY:

PINCHED:  PLASTIC CLAY is pinched into a shape.

COILED:      PLASTIC CLAY is rolled into coils and joined to create a shape.

SLAB:           PLASTIC CLAY is rolled into slabs of uniform thickness, cut into shapes that are ‘stuck’ together using a glue-like slip.

MOLDED:    LIQUID SLIP is poured into a plaster-of-paris mold. Water in the clay is slowly absorbed by the plaster.  When a clay wall of specified thickness develops, excess slip is poured out. The remaining clay wall shrinks from the mold as it dries.

THROWN:    A BALL OF CLAY is thrown and centered on a revolving potter’s wheelCentrifugal force and water assist the hands of the potter who simultaneously applies pressure on the outside and inside of the whirling clay to control shape and height…..and a pot is born.  Throwing is traced to the Middle and Far East as early as 3,000 B.C. 

Uniform thickness is critical for every shaping technique in order to assure successful firing. Uneven clay bodies crack or explode when fired.   Artisan dinnerware is relatively uncommon although mass-production factories employ artisan techniques for some of their production.
            

MASS-PRODUCTION:    FROM CLAY TO GREENWARE     

                                                MOLDED HOLLOW SHAPES:  

Plaster-of-Paris molds are integral for mass-production of dinnerware.

Every factory I visited had a MOLD SHOP where the non-mechanical method of forming hollow shapes using plaster-of-paris molds is called slip-casting.

Models of a finished shape are first made in plasticine, wax, or plaster by skilled artisans who must consider the shrinkage of clay that occurs in both the green stage and bisque firing.  A negative mold is made from the model and in a sequence of positive and negative castings, plaster working molds are made for mass-production.

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Hundreds of identical molds are required at the same time for production of hundreds of duplicate shapes and after every usage, molds must be thoroughly dry before being used again and again.

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Liquid slip (a prepared suspension of clay and water)  is poured into a mold. When a sufficiently thick wall  of clay clings to the mold, excess slip is poured out.  As clay dries, it shrinks, is removed and is now called GREENWARE.

The dried clay shape is inspected and perfected to meet rigid quality standards. e.g. excess clay can be trimmed from edges—which are smoothed against a wet sponge before firing.

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In shapes having a relief or embossed design, recesses of the plaster mold become clogged with clay residue.  After approximately 20 pourings of slip, molds are replaced in order to maintain uniformity of the relief. This cost is incorporated in the price of the pattern.

OTHER SHAPING TECHNIQUES: 

The production of plates requires a more solid form of clay.  Liquid slip is pumped into cloth bags for filter-pressing.  Water is pressed out and semi-dry cakes of clay are put through a pug machine to be well-mixed and extract air. This firmer and more plastic clay is extruded into ‘giant clay sausages’ called pug.  Sliced pug is used for jiggering and jolleying techniques.

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Jiggering is a mass-production technique for making plates.  Thick slices of pug clay are deposited on spinning upside-down plaster plate molds.  A template lowers to stretch the clay to a uniform size and thickness.  Making five to six hundred plates a day requires five to six hundred molds a day.  Molds must dry thoroughly before they’re used again. 

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Jolleying is a mass-production technique also for hollow shapes as bowls.  Slip is poured inside a revolving plaster-of-paris mold and forced against the interior walls of the mold by a metal template to assume the mold shape and determine the proper thickness.

Paste-Up Techniques:
Handles, spouts, lids, and other components are individually cast in molds and pasted’ by hand on the greenware body of each piece. Liquid slip performs as paste/glue. To the eye, these components must be attached without visible joining.

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QUALITY CANNOT BE ‘ADDED-ON’

 Pat Breen: EYEWITNESS TO QUALITY

 My next post is: FIRING CERAMIC DINNERWARE

KINDS OF CLAY©

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Rock metamorphoses into clay which is shaped, cooked and decorated by man to suit his needs. Despite the simplicity with which clays were dug, shaped and cooked by sun or fire more than 10,000 years ago, current ceramic technology includes locating,transporting and combining clays and other ingredients from all parts of the world, creating glazing formulas and techniques and kilns capable of firing clays at very high temperatures.

Granite/type igneous rock account for much of the earth’s crust. Natural hot gases decompose these hard rocks into soft rock containing feldspar minerals which are further broken down by rain, sun and ice into CLAY; a generic classification of fine grained earth and the raw material of ceramic dinnerware. Some clays contain minerals as mica and quartz, some contain kaolinite called china clay.

Each kind of clay has different degrees of porosity, plasticity and purity that contribute character and durability to dinnerware but they present challenges to manufacturers who require many specialists to manage technical variables as shaping, glazing and firing.

Clay that remains where it’s formed,  is primary or residual clay.

Clays carried thousands of miles from their primary source by wind, glaciers, rivers, and the sea are secondary or sedimentary clays.  During their journey, they’re ground, collect impurities and eventually settle.  These clays vary in color, are finer, more plastic, and less pure than primary clay. A significant impurity is iron. Clays are blended by manufacturers   to assure uniformity for production.

There is also variation in the minerals and purity of the water with which clays are mixed  and each manufacturer develops their exacting formulae to achieve uniformity of quality and exclusivity.  From hands of artisans to machine techniques of mass-producers, every culture has produced ceramic dinnerware shapes, sizes and patterns to enhance their culinary arts.

Dinnerware departments in retail stores sell dishes made of different clays as porcelain, bone china, stoneware and earthenware.

Each kind of clay has a maximum firing temperature established by the temperature that would cause a shape to lose definition; called its’ slumping point. Generally; the purer and finer the clay, the higher the firing temperature, which explains the strength and durability of dinnerware that looks fragile.

The following dinnerware categories are made of clays with distinctly different  characteristics:

POTTERY:
A general label for low-fire porous clay products.

EARTHENWARE:
Low-fire, opaque, porous clays requiring glaze to become non-porous.

STONEWARE:
High-fire vitreous, opaque clays.

PORCELAIN & BONE CHINA:
High-fire vitreous clays; translucent if thin.

NATURAL CHARACTERISTICS  OF CLAY:

POROSITY: Most clays are porous in the bisque stage and require glaze to seal porosity.

NON-POROSITY:   Some clays are vitrified (non-porous) in the bisque stage.  All elements are fused and the bisque is impermeable to moisture.


PLASTICITY:   Clays that can be easily modeled or shaped.


PURITY:   The purity of each clay determines its firing temperature. The purer the clay, the higher the firing temperature—which makes some dinnerware more durable. e.g. porcelain.

POROUS CLAYS:

EARTHENWARE :

EARTHENWARE clays are sedimentary clays. Some are more pure than others and range in color from light buff to dark sienna. These clays are fired at relatively low temperatures and although earthenware products look sturdy, they chip easily. Earthenware is porous and must be glazed to seal the porosity.

TERRA COTTA  (cooked earth) is red earthenware containing iron oxide. Unglazed terra cotta is used for flower pots because its’ porosity enables potted soil to breathe.

CREAMWARE  was an important development in making pale earthenware. It preceded glazing techniques that made earthenware resemble white porcelains from the Orient.

NON-POROUS CLAYS:

STONEWARE:
Stoneware originated in China but was not introduced for dinnerware until the late 17th Century in England.  Stoneware is a composition of clay and fusible stone.  In the bisque state some stoneware is vitreous; some is semi-vitreous.  Stoneware matures slowly as it’s fired at temperatures higher than earthenware. It becomes dense and durable when glazed and fired.

Natural stoneware colors vary from almost white to dark brown.
Transparent glazes are applied when a manufacturer wants the natural color of the clay to show through.  Opaque lead or earthy salt glazes are also commonly used.  Lead burns out in firing.

IRONSTONE is English earthenware containing slag of iron. It is called stone china because of its durability. Do not confuse ironstone with stoneware.

PORCELAIN: 
The Chinese defined as a “development of fine stoneware” containing fusible stone. True porcelain, hard-paste, is fired at a very high temperature enabling clay and glaze to mature together. Porcelain does not exist in nature as clay.  Diverse formulae include:

  • kaolin: The purest of primary clays; indispensable for producing translucent porcelain.
  • ball clay: Clays, once-removed from primary kaolin clays, which add plasticity.
  • feldspar: Ground rock which helps bind all ingredients.
  • flint (silica): Substances which turn to glass during firing and impart hardness and freedom from warping.

Porcelain is the most pure of ceramic wares–and the reason  it can be fired at high temperatures. It is very white and very strong.  Porcelain is vitreous (non-porous) in the bisque stage and glazed only to provide a glassy surface for food and avoid stains. Porcelain wares can be made so thin the wares are translucent, yet exceptionally strong, and resonant when struck with a pencil. Porcelain can also be made heavy enough to be oven-to-table cookware.

OTHER PORCELAIN WARES :

PARIAN:   Unglazed granular porcelain resembling marble; also called statuary porcelain.

BELLEEK:
 A highly refined translucent porcelain with a luminous glaze and made in Ireland’s first porcelain factory which opened in 1857 in Belleek.


SOFT PASTE PORCELAIN 
(pate tendré):  A mixture of white clay and ground frit but without kaolin.

BONE CHINA:

Bone china, introduced by Spode in 1800, is a form of soft-paste porcelain made to duplicate the appearance of Oriental true hard-paste porcelain.

Bone china combines 50% animal-bone-ash with clay to lower the firing temperature and increase translucency. It contains no kaolin. Glazes for soft-paste porcelain and bone china are fired at lower temperatures than hard paste porcelain.

WE NEED LABELING TRANSPARENCY

 Pat Breen: EYEWITNESS TO QUALITY

My next post is:  CERAMIC DINNERWARE PRODUCTION

THE STORY OF DINNERWARE©

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Read how dinnerware originated and continues to be artisan and mass-produced today. Sequential posts explain specific generic standards of quality from raw materials to finished products —entrusted by experts in renowned international dinnerware factories. I share them so you can JUDGE FOR YOURSELF.  

Brand names change, styles change, prices change:
generic standards of quality for everyday home products do not change.

EVERYDAY HOME ESSENTIALS explains my concerns about quality.
ABOUT is about me. 

Early dinnerware was made of clay indigenous to a geographic area.

From the clays, glazes and decorations of Pre-Columbian, Egyptian, Greek, Roman, Middle and Far East earthenware pottery— circa 3,500 B.C., historians gained insight into their cultures.

We learn how early man not only cooked food in clay; he shaped, fired and decorated clay objects from which to serve and eat food–and we appreciate—primitive man wasn’t so primitive!

Porcelain surfaced in China.  The wonder is that it originated
at all—because porcelain is not found in nature.  By 1,000 B.C.,
the Chinese developed stoneware by adding fusible stone to clay.
Over centuries, stoneware clays were blended with kaolin and
petuntse, a fusible form of feldspathic rock.

By the 13th Century, a formula had been perfected to produce translucent white ceramic that Marco Polo described as alla porcella –because it resembled translucent sea shells shaped like a little pig—and was forever more known as porcelain.  

Intervening centuries and trade routes brought porcelain to the West. By the 17th Century, spying and poaching of talent proliferated as monarchs of European countries supported efforts to imitate Chinese porcelain.

Earthenware, low-fire porous clays ranging in color from light buff to dark sienna, were already made in Europe.  Experiments to make porcelain-like products consisted of glazing earthenware with lead glazes containing tin oxides, thereby producing a white glaze to hide the color of the earthenware.  Colorful designs were painted over the white glaze and diverse styles were identified by names we still use; Faience, Mailoica, Majolica and Delft.

Soft paste porcelain (pâte tendré), a mixture of white clay and ground frit (materials of glass making), but without kaolin  “became the vehicle of genius in the hands of the potters at the factory at Sevres, France” wrote Curator, David McFadden.

Kaolin, the ingredient that lends hardness and whiteness
to true hard paste porcelain (pate duré) was finally located
in Europe in the 18th Century. Experiments at the royal
fortress at Meissen led to the technology of combining
kaolin with silica and feldspar (petunse was not found in
Europe) and the making of porcelain wares soon spread
throughout Europe.

Josiah Wedgwood opened a model ceramic factory in 1767. He divided factory space to enable spatial flow of production— allowing labor to become highly specialized. His factory system became a model for the mass-production of dinnerware.

Bone china, introduced by Spode in 1800, is a form of soft-paste porcelain that resembles true hard-paste porcelain but contains no kaolin.  It is called bone china because 50% ground animal bone-ash is combined with clay to lower the firing temperature and increase translucency.

After the Industrial Revolution created a middle class, dining
rooms with china cabinets became the way to display culinary
skills as well as new possessions.  American ladies commonly
took china painting lessons using blank porcelain wares
imported from many factories in Limoges, France.

At factories, steam power facilitated the grinding and preparation of raw materials and ‘throwing wheels’ previously dependent on wind or water mills.  Kilns require intense heat (to make clay stone-like, durable and functional)—so dinnerware factories were usually located near forests.  Eventually, wood heat was replaced by coal—much later by gas —and eventually, electricity.

Technical advances in uniform production and decoration coupled with global demand have made dinnerware a successful international product since the 19th Century.

DINNERWARE TODAY:

At home or restaurant, we eat from diverse sizes and shapes of a hard, vitreous material that’s washed and used repeatedly—called DISHES.

We buy dishes in sets,
or by the piece,
or by the place-setting,
in retail Dinnerware Departments.

There are thousands of dinnerware patterns available today—each—only as good as the materials and methods used to make it.

Visiting several international dinnerware factories, I was amazed by the vast real estate required for the labor and capital intensive production of dinnerware. Because of the need for exact duplication of diverse shapes and sizes by the hundreds, dinnerware is mass-produced using diverse techniques that we’ll later examine.

It’s crtical to understand raw material differences
— because each kind of clay contributes different character and durability.

Many labor intensive production techniques are necessary for making diverse dinnerware shapes: each requires working with clay in different ‘wet’ stages—from ‘liquid slip to pug’.

A highlight at one factory was their final step:
inspection – rejection –destruction.
Cup or casserole—any piece not meeting standards of excellence was destroyed.

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When handed a stick to participate in the destruction,— I couldn’t!

Of course we want good dinnerware
—regardless of taste and income—
but how do we know if it’s good?

Many people equate high-price with high-quality but there is no price/quality ratio. Factors impacting the price of dinnerware are country of origin, availability and cost of raw materials; skilled vs. non-skilled labor, and design, sales, distribution and promotion costs.

DINNERWARE NEEDS LABELING TRANSPARENCY.

I am cynical about everyday essentials advertising—in any media!
In addition to brand-bias, dinnerware advertising perpetuates myths
.

Newspaper ads and catalogs push only color and pattern names:
most don’t even mention the name of the kind of clay.

Many retailers have advertised dishes made of ‘chip-resistant white clay’
—a specious phrase to create an impression of durability—
and meaningless because the specific kind of clay is not given.

ALL DISHES CHIP:
because each kind of clay has a different tolerance of durability.

Currently, because of rising labor and raw material costs, many prestigious dinnerware manufacturers have merged with– or been acquired not only by other dinnerware companies; but also by glass and flatware companies.

Many international dinnerware brand-manufacturers outsource production to save labor, manufacturing and marketing costs. Many designer and store brands of dinnerware are produced this way.

Once you can judge the quality of dinnerware for yourself.
Who knows?
Perhaps you’ll fall in love with your grandmother’s china.  

PAT BREEN: EYEWITNESS TO QUALITY

My next post is:   KINDS OF CLAY