A Paper Presented to the Faculty of the Graduate School University of Minnesota, Duluth

By Laura K. Carlstrom Master's Paper (Plan B) University of Minnesota Duluth, Minnesota July, 1973 To - Mr. Glenn Nelson

"The true teacher defends his pupils against his own personal influence. He inspires self-distrust. He guides their eyes from himself to the spirit that quickens him. He will have no disciples." CONTENTS

INTRODUCTION IV

CHAPTER I History of Salt Glazing 1

Germany 1

England 10

United States 14

CHAPTER II Process 17

CHAPTER III Modern Developments 22

CHAPTER IV Personal Experiments 26

CHAPTER V Conclusion 46

BIBLIOGRAPHY 48 INTRODUCTION

Making a thought Into a form Wheel spinning, stretching, softly -­ Serendipity.

Ceramics has been fun for me because I could get my hands, face, clothes, and everything dirty. Your fingers could create things out of this sticky mud. This earthy quality of the clay was what first motivated my interest in pots.

The natural quality I enjoyed about clay, in IDmbination with the interesting contraption in the corner of the studio (which vras never touched) attracted my attention. This crazy,f~ling-apart contraption seemed to hold a challenge.

I knew nothing about salt glazing, but I liked the earthy quality that this type of glazing gave the pot. The first major obstacle was to figure out how to get the salt kiln to function, and the second was the effect the salt glazing procedure had on the chemicals we were using. My interest grew after I made a successful non-glazed pot that retained the natural quality of clay. The salt process became a convenient tool to retain that natural clay quality, and still have a glaze.

As I read I fully realized how vast an area of research salt glazing was, and how little of it I had been able to uncover.

I felt that my tests were incomplete because of the number of possible experiments that could have been accomplished.

The intent of my paper is first to give a brief historical back­ ground on salt glazing from its origin to the present form. Secondly,

I would like to explain the process for thoewho have not experienced the fun of having a salt glaze firing, as well as the advantages and disadvantages. Next, I would like to talk briefly about some modern developments and uses. Finally, I would like to explain my experiments and their resultso Chapter I

HISTORY

The date and origin of the discovery of salt glazing is a mystery in itself. An exact date for the first salt glazed ware is not known. (According to such sources as Mr. Glenn C. Nelson,

Angelo Garzio, and others) glazing by volatization was being done by potters along the Rhine River Valley between the twelfth and thirteenth centuries. The Rhine River potters were producing salt glazed pottery by the fifteenth century. Early in the sixteenth century the northern parts of Germany manufactured it extensively. Controversy exists as to the time of discovery, but we can be certain that the are~ of the Rhine was the place where the disco'lery originated. Salt glazed ware was, for the most part, a German invention, but in:a short period of time the process spread to England and then to the United States.

The development in Germany was rapid. Several large communities began to manufacture high quality work. These

German towns also gave the ceramic styles their names. The large abundance of stoneware clay, high in silica, near the

Rhine may have been the cause of the rapid growth of this work.

Different potteries can be identified by the shapes, types of clay bodies, and salt appearance.

Siegburgware or Cologne ware, manufactured in an area 2 called Siegburg, is believed to be the earlies: type. This factory is generally known for the sixteenth century white ware. A coarse brown-grey ware, however, was believed to have been produced at an earlier date. Most historians consider the white ware as more artistic works. I disagree with this opinion. I prefer the more natural effect and earthy quality over the more refined white ware. The white ware had a very thin blotchy glaze. The common shapes of the Siegburg pottery are tall cylindrical types, and jugs with cylindrical bodies and long necks.

The most characteristic are the tall drinking vessels, or

11 cannettes". They are cylindrical and tapered to the top. They have rings at the top and bottom which resemble that of the earlier designs in long, separately-attached columns. Usually the pot has three panels that run up the sides. The subjects of the panels are usually medallions, coats of arms, masks, scriptural scenes, and dates. These pots usually have a dry surface or very thin glaze, with glassy patches. They look as if the glaze may have been absorbed. There are excellent examples of cylin­ drical Siegburg pots at the Pennsylvania Museum.

The second typical Siegburg pot shape is a baluster-shaped jug, with a globular body, a cup-like mouth, .and a broad foot.

A sign of this type of pot is a thumbing or pencil mark at the foot, forming a wavy outline. The handles of the baluster jug are circular or ring-like, just large enough for the forefinger. To review, tha main characteristics of Siegburg are light colored clay, only a thin coat of glaze, stamped pane+ decoration, and thumb print designs at the bottom.

Another important German pottery is Raeren. The following are the principal characteristics of Raeren ware. The pots are stoneware of a greyish or yellow body. They have a heavy metallic glaze which varies in color from a deep reddish-brown to a pale dirty yellow. These pots are usually freckled or mottled in places. They resemble a thick coat of lead and a deposit of salt glaze. The pots look as if they are molded in sections and joined together. The secions are decorated with heavy reliefs.

The following is a list of the most popular subjects for the

Raeren ware: peasant dances, works of mer-cy, biblical scenes, arms of tov;ns and individuals, and medallions containing badges or masks. Factory marks are not usually placed on ancient stoneware, but on Raeren ware letters and monograms which represent abbreviated incriptions or initials of merchants for whom the pieces were made.

A third area is the Frechen Area near Cologne. Freehan is the ancient centre of salt glazeq w~re in Germany. This ware is close in color and form to Raeren pottery but many Frechen products have well-marked peculiarities. Let 1s compare Frechen to Raeren. Frechen has a black glaze, while Raeren has a brown tint. Frechen has a more coarse, simple decoration than does the Raeren ware. 4

The most common shape is the Greybeard, known in Germany as

Bartmann or "bearded man". It was often imitated in England as

Bellarmines. The cup was named after Cardinal Bellarmine, who was in opposition to the reform religion. The Bartmann cup was a satirical representation by 'the Protestants of the low countries.

Depicted was a man of short stature, hard features , and a rotund figure. This shows that the potters were reacting to the social developments of the time.

Greybeard has a spherical body, tapering at the neck and foot. On the narrow neck there is an elongated bearded man.

Another Frechen shape is the cannette , which has boldly modeled decoration and a black glaze. Arecorative detail widely used was a coin-like medallion. This medallion has a band of inscriptions around the center with a border of vines and scroll work around it. Frechen ware was cut from the wheel. Important identification marks are the grooves from t wisted wire. The following photograph is a seventeenth century Bartmann. 5

The following are the important factors in Frechen:

1. Gathering of brown glaze into spots. 2. Wire work on bottom. 3. Coin-like de'sign. 4. The 11 Greybeards" •

The Kreussen Pottery was famous during the mid-sixteenth century in Bavaria. The earliest dated pots of this type are from the early seventeenth century. This type of pot had dark brown clay ~~th a very thin glaze. The most common shapes of the

Kreussen are jugs, jars, and mugs. The very early pots were rusty brown and we have found fragmentary reliefs of the Apostles. The mugs from this period were broad squatty forms. Drug jars were also popular. They were barrel shaped, and had four to six flat panels on them. An interesting point here is that the surface was worked with a brush until it looked smooth •

.An easy identification is possible because of the peculiarity of the Kreussen pots. They have an unglazed circular place near the center of the base. This section is several inches in diameter.

This was caused by the way they stacked the pieces on top of each other in the kiln.

The later period was very different. The pots hq.d bright opaque enamels on them of yellow, red, blue, brown, and white.

Their colors resembled ail colors. These enamels were applied to the relief decorations and gilding was used as a final decoration.

Some of the decorations were of Apostles. The mourning jugs of 6

this period were decorated with black and white geometric patterns.

Several authorities believe the use of enamel and gilt colors marks

the decadence of the art. The characteristics again are dark brown color, (looks like iron rust), use of enamels, gilding, and unglazed places on the base.

Early Grenzhausen is very similar and has Raeren influence.

The later pots of the seventeenth, eighteenth, and ninteenth

centuries were grey. The later ware was more originally styled.

They had free hand incised designs combined with molded ornaments.

A new technique arose where patterns were dug out and filled ,,,. in with colored glazes. This technique was termed champleve.

The colors us-ed were cobalt blue and more manganese purple or brown, because, as colorants, they can withstand very high temperature.

The Grenzhausen had a iarge variety of forms. Some Grenzhausen are composed of white clay resemblihg Siegburg, having incised designs or relief ornaments. Little pads of clay were impressed with small stamps.

Much of the modern Grenzhausen ware is copied from earlier forms. They are usually made of bluish-grey clay instead of white and brown. They are decorated with stains of blue and purple.

The most popular Grenzhausen are tall cannettes of Siegburg as well as the peasant's dance jugs of Raeren. The following photographs are modern pots from Grenzhausen.

8 9

Grenzhausen characteristics are as follows:

1. Grey or bluish grey body 2. Incised and sunken ornaments 3. Molded reliefs 4. Use of blue, purple, and brown enamels 5. Handles are curled up at lower ends, making loops for cords

The most important remaining pottery in Germany is Grenzhausen

because of the abundance of natural clay deposits and the established

local schools.

Bouffiax works were imitations of others, but the decorations were crude. The earlier brown stoneware are like Raeren and Frechen.

The later were grey blue of the Grenzhausen. The decorations were usually single medallions and grotesque masks. England

The exact date of salt glazing in England is also a question.

According to several sources, during the seventeenth century, about

1690, the method of salt glazing was conveyed to England by Brothers

Elers. T'ne English preferred white clay and brilliant colors over

the earth tones. The English wares were very high fire because of

the type of white clay (kaolin) used. This white clay needed the

high temperature for vi t:cification. Most of the work was slip

painted, incised, or embossed.

In 1688 John and Philip Elers left the Delft potteries in

Holland and came to England. Shortly after, their arrival they

began a pottery in Bradwll Woods, where there was a great abundance of red clay. Their work was stoneware, vhich was dense red and semi­ vitrified. The work was thrown and lathed. The lathe process is an industrial means of forming a pot. A metal die was -used to press in the clay for decorations. They may have used this idea because they were silversmiths as ~well as potters in England.

These two men were supposedly responsible for the introduction of salt glazing into England. Even at that time, as several potteries grew up, there were protests because of smoke.

The Elers introduced many so-called technical improvements such as the lathe-stamps, alabaster molds, and refined clays. The

Elers used molds to cast pots and considered this an improvement. 11

The cast process and the use of sta.mped desi6'1ls created a more commercial-looking product. This process detracts from the natural­ looking q ua.li ty that a clay vessel should possess.

The Englishware, after the Elers, can be divided into sections:

1. Early brownware at the Fulham and Nottingham factory, 2. Whiteware from the Staffordshire, and 3. Modern brown from the Lambeth.

In 1671, John Dwight, of the Fulham pottery, took out a patent for his discoveries of the "mysteries of the Cologne ware". Only a few of his works are known, and are VFell respected.

The Fulham factory potters made mugs, tankards, jugs, Bellarmines, and beer bottles, all bearing medallions and the initials of English rulers. Dated work has been found from 1721-1764. Many works a.re very similar to the Grenzhausen of the same period. There is one difference that distinguishes the two, and that is the manner in which the handles are attached. The handles are pointed at the ends where they are attached. But in general, the Fulham ·.vare have never been marked, and are often a mere reproduction of the types imported from Flanders and Germany. Identification rests in most cases in mere speculation.

Nottingham ware is a brown salt glazed .Etoneware ma.de throughout the eighteenth century. The earliest dated piecevas made in

Nottingham in 1700 and the latest in 1799. The salt glazed ware was covered with a wash of high iron content clay, which gave it the burnt to brown sheen. 1 2

Nottingham ware was carefully thrown, and turned on the lathe.

Any decorations were scratched on the unfired clay with a sharp

point. The handles were made by hand, not thrown or cut.

Typical pieces are loving cups, puzzle jugs, mugs, punch bowls,

and curious jugs:in the shape of a bear. The surface of these

bears\as covered with clay shavings to represent fur. The bear

baiting and fighting were common positions. Later, a Russian war

bear was made hugging Napoleon in a deadly embrace. This was the

first produced at the beginning of the eighteenth century.

Nottingham works were well potted, graceful forms with crude,

simple decorations on them. They were bright, with a s;rong red­

brown tint, and a metallic luster. The common forms were mugs,

pitchers with ribbed or horizontally-corrugated necks, two-handled

cups, and the "bear jugs".

The Staffordshire pottery opened at the close of the seventeenth

century. The work had a white body, was very thin and graceful, and was fired at a high temperature. The thinnest parts of the work were translucent. Professor A. H. Church has made the following division of the manufactur·e of white salt glaze ware:

Previous to 1720, Archaic period, when impressed and applied

ornaments were used on thrown or turned. vessels of drab

white or white clay.

From 1720-1740, Flint added (fine sharp work) stamping or pressing 13

of metal dies or casting, no color, white clay.

From 1740-1760, Colored enamels employed for decoration on surface.

From 1760-1780, Basket and pierced work was prevalent.

Patterns were scratched in the damp clay and a blue color rubbed in

called "scratched blue". 1_750-1780. William Littler used a solid blue background, by dipping them'while still in a partially-dried clay state into a slip of the same ingredients and blue color.

Some were painted with enamels in the Persian style done in a second firing.

The first products were produced a; Lambeth in 1751. They ranged from rich, reddish-brown color 1o a buff or yellow hue.

The body was spherical with a broad perpendicular collar. The upper edge had been pinched out to form a small triangular lip.

A molded ornament was used to decorate the handle ends.

The most popular ware was produced at Lambeth in 1815, when

John Doulton came to the factory. The most characteristic and artistic of his works were the decorations scratched on. the plain wet surface of the ware. One of the best artists in this work was Miss Hannah B. Barlow. She did animal pictures with as few lines as possible. Other a-tis ts were: Mr. George Tuni voi th,

Mr. Arthur Barlow, Miss Florence Barlow, and Mr. Frank Butler.

Lambeth then had a rebirth of the types of pots it was producing.

They developed the use of colored salt glazed ware. The old works were all browns of varying tones. United States

German and English settlers brought pots as utensils to the

United States. Some of these pots were used to barter with the

Indians, and a few have been found in their graves.

Salt glazed stoneware has been made in America since early in the eighteenth century. The first products were crude and simple in character, in the form of crocks, jars, and other utilitarian articles, entirely without decoration. Some may have had an occasional dash of blue or a few incised ornaments.

John Remmey, a German, established a pottery in New York City about

1735. By 1742, the pottery was run by Remmey and a man thought to be his son. Remmey died in 1762 and his son took over.

Abraha~ Mead, at an early age, was an apprentice to a Dutch potter, Adam States. States had established a pottery in Greenwich,

Connecticut in 1750. When Mead was very young, he fired a salt kiln while his master was away and mastered the skills of salt glazing. There is a rumor that between 1761 and 1769, at the time of States• death, Mead took· over the pottery, but no record of this -transaction was kept. There are seven good examples of Mead •s work, three of them marked with initials applied with cobalt slip.

These pieces have pronounced European characteristics, reflecting 15

the work done by Adam States. Two jars have upward curving

horizontal handles and scroll motif. More noteworthy is a small

h§ndled jar, covered with a triangular design.

Paul Cushmann began a pot shop in Albany, New York in the late

eighteenth century. The bodies of his pots had brownish tints and

scanty cobalt decorations. The following is a iist·or other

potteries in operation previous to the ninteenth century: Norwalk,

Connecticut; Morgantown, West Virginia; Huntington, New York;

Bennington, Vermont; Norwich, Conne·ctic"ut; Utica, New York.

On January 28, 1772, the Pennsy.lvania Society for the

Encouragement of Useful Arts had a contest for the best salt glazed

work. The prize was fifty dollars. Even by._ this early date, salt

glazed ware was very popular.

Soloman and Samual Bell of Hagerstown, Maryland began a

stoneware pottery in 1842. Among the best pieces produced during

the early years of this factory is a large grey stoneware water

jug, with handles modeled to look like. serpents and human masks,

surrounded by impressed ornamental patterns. On the body are

boldly painted tulip designs in rich cobalt blue. This pot bears

the stamp of Soloman Bell.

Charles Wingender and Brother, of Haddanfield, New .Jersey, are among the few potters in the United States who continued to 16 produce the old-fashioned German grey salt glazed ware with blue and purple decorations. Some of the old molds which had been used in Germany for a century or more are still in use at their pottery, but many of their best designs are original •. Their beer steins, jardinieres, pedestals, and water colors are modified after the old German forms, and compare favorably both in decoration and style.

The Fulper Company of Flemington, New Jersey, primarily manufactured drain tiles at the beginning. Later, other articles were added, such as drinking vessels for poultry. After 1860 the company began to produce beer mugs, bottles, water and vinegar jugs, butter churns, and pickling jars.

Generally, the United States has been most influenced by the

Flemish and German stoneware, not the English whiteware. The salt glazed ware was used mostly fors:;orage and utility purposes, until recently, vhich I will discuss in a later chapter. Chapter II

PROCESS

I will now explain the process of salt firing, how it works,

the advantages and disadvantages, and the results. The process is

actually very simple, but conditioning, accidental happenings, and

the clay body itself make it very exciting and undependable. The

control the potter has is limited and lets accidental natural

happenings take over. A greenware pot is placed in the kiln, fired

to the maturing temperature, and at this point salt is added to form

a glaze.

Salt glazed pots are fired raw, and they can be decorated with

a slip, engobes, or glaze. The ware is fired to the clay maturing

temperature. At this point in the firing salt soaked in water is

added to the kiln. It can be added through the por.ts of the fire­

box. The silica from the clay body combines with the sodium in

the salt to produce~ sodium silicate glaze on the pots.

2 NaCl + H20 2 HCL + Na2o Na2 0 + Si02 Na20 + Si02 Coal, wood, or gas kilns are suitable for salt glazing.

Electric kilns are not desirable because they are generally re­

stricted to an oxidation fire. The down-draft kiln is the best

type. The kiln should fire with reasonable even distribution of heat and should be vented. Venting of the kiln is important 18

because of the poisonous chlorine gas given off during salting.

To prepare the kiln for salt firing, you should coat the kiln

furniture and shelves with aluminum hydrate or a combination of one

half alumina, one half whiting, plus ten per cent kaolin. One half

inch should be left between pots for good circulation, also a good

deal of space between shelves. The temperature to 'Vlhich the kiln

is to be fired depends on the particular maturing temperature of the

body {ll04,6010), but can be done from (l.02➔ ~12). Lower temperatures

need borax added to the salt to help lower the melting pointo l\12•~5 is not h-igl:1 enough for a good glaze, but~6 or over will

produce desirable results. Determining the temperature depends on

the color of the atmosphere in the kiln. Cones in salt glazing

are of little use because they are affected by the vapor. Draw

rings are useful, placed near the top and bottom peep holes.

T'nese rings can be taken out during the course of fire for inspec­

tion. The dampers should be partially closed while salting is

taking place.

The following are important points to remember about the salt when preparing for a salt glaze fire: You mould use coarse, common salt (sodium chloride). Salt brine can be used, but is not as effective. The salt must be soaked in water before salting. The water provides oxygen to form sodium oxide. About five per cent of water in the salt is necessary because it retards the volatization of the salt. The moisture in the damp salt causes the coarse 19

particles to explode, thus dispersing the salt throughout the kiln.

The amount of salt you use depends on the size of the kiln. For

every twelve cubic foot capacity, one pound of salt is necessary.

The more salt you use, the thicker the glaze surface will be.

In the school kiln we use six to seven pounds of salt during a

normal salt fire. An older kiln needs less salt because the bricks

and furniture have already been coated with glaze. A new kiln will

absorb much of the salt to coat the interior, _making it necessary

to use more salt.

Most clays will salt successfully, but it is better if the clay

is rich in silica; sixty-five per cent or more in the clay body is

necessary. Also, some free silica will make a richer coat. The

clay mould be as free of groglll possible. Grog will not be covered

by the salt. The color of the clay will show different results. You

can use any ~lor clay, from white to very dark brown, giving a range

of color from white to tan to black. Colorants and other chemicals may be added to the clay body and surface.

The damper must be closed after the final salting to slow down the cooling process. Cooling is an important factor in the results. A fast cooling will cause a glassier surface, and is destructive to both the pots and the kiln. Waiting to unbrick the kiln is always exciting because you really do not know what happened in the firing. Even the craw rings ere not a good indication because their rapid cooling changes the effect of the surface and the color. From time to time potters have tl'ied to improve the 20

appearance of salt glazed ware by the use of slips and engobes

containing white clay, flint, feldspar, and colorants. The color

of the pot may be altered by adding different chemicals to the

clay body.

White or tan = iron content below 1% low silica Light brown = low silica to 3½% iron Brown = 3½% - 4.75% iron Mahogany = 4.75% - 8.2% iron

(Higher iron should be fired at lower temperatures). Cobalt and other colorants in the body have been experimented with to cause color effects.

Materials may be added to the salt to change the effects of the surface. Three to five per cent borax creates a smoother glassier surfacd. Oil plus salt causes more intense colors because it fires hotter and has impurities that will cause a greater reduction. T'ne addition of rutile to the salt makes the glaze matt and thin. Also, the more salt and more free silica in the clay causes a thicker "orange peel" effect.

Decorations may also. be added to the surface of the raw ware.

Stains, slips, glazes, and engobes may produce decorative color designs. Engobes are made :from china clay, feldspar, flint, and colorants.

The salt glaze color range is more limited than an oxidation fire. The following is a list of chemicals that produce successful 21 results in a salt fire:

cobalt= blue iron = brown rutile = ochre lead = brighter colors albany = green (cheap and reliable)

The above p~oduce constant results. Many other colorants can be effective through experiments, but not always constant or reliable.

Salt glazing is popular, not only because of the exciting natural effects, but for many practical reasons. Salt glazing does not require numerous materials or a great knowledge of chemical reactions. This type of glazing has been popular for utilitarian purposes because the material is cheap and dependable.

Unfortunately, it also has disadvantages. It is very undepen­ dable as far as achieving a desired look;you have little control over the results. An experienced salt glaze potter can expect more constant results. Color is difficult to achieve, repeat, and control. Another big• disadvantage is the chlorine gas that is given off. This gas is very toxic. When the salt burns the chloride separates and combines with water vapor, and escapes from the kiln in the form of hydrochloric acid fumes. The salt also causes rapid deterioration of the kiln and kiln furniture. The glaze coats the kiln and furniture as well as the pots. Salt remains from previous firings in the kiln and circulates in the atmosphere, causing it to be undesirable for regular glaze firings. Chapter III

MODERN DEVELOPMENTS

History has shown that salt glazing was generally used for

utilitarian purposes. Sewer pipes, tiles, and functional pottery

were the major concerns of the Germans, English, and the early

United States salt glazed potteries. Recently, ceramics has grown

increasingly more important as a decorative art for the general

public. Also, salt glazed ware has grown rapidly in popularity as

works of art as well as utilitarian objects. Artists seem to

recognize the earthy quality of the material and thestlt process

has become an ideal process to express this quality. There has

been a Renaissance of salt glaze ware in the United States during

the twentieth century.

Don Reitz is one of our modern developers of salt glaze in

the United States. I chose him to illustrate the changes in the modern movement in ceramics because his work is representative of

the new trends in salt glazing, and I feel he has had a great influence on contemporary potters. His work is very plastic looking, colorful, decorative, and extremely inovative. He has

tried a variety ot experiments and techniques new to modern salt glazing. His work is far ft-om being strictly utilitarian. For

Don Reitz, clay is what he is about. 11 It 1 s clay that is the nucleus ofcy' philosophy of what life is about. When I talk, people think 23

I'm talking about clay, but I don't separate clay fromey life. My work, my family, my farming, my teaching, cy religion are all one.

Some days I plow the fields, wor~ with my horses, or teach at the

University of Wisconsin; it's one flowing event. I let each day build, as when I throw a pot. 11 It seems that with this philosophy salt glazing is an ideal material for his artistic expression of feelings.

A potter, according to Reitz, must work intuitively. ''He must be flexible enough to identify completely with his material and daring enough to allow himself to be shaped by the clay."

Reitz•s experiments with clay are governed, first, by the dictum that "everything melts and clay shrinks", and second by his av1are­ ness that salt glaze reveals the surface of the clay. He uses three decorate devices: wet slips, tools, a1d additives to the clay. Other possibilities are raw oxides rubbed into the wet clay, mixing oxides and vater to get a work or an air brush to spray decorations on the pot.

Because of the results of salt glazing his pots are generally highly textured. The surface is covered with scratching from needles, sticks, clay stamps, and a comb. Textural pots, after they have been salted, have a nice mottled surface and salt build-up.

Eight years ago he began salt glazing, after having been stifled by the use of common glazes, which covered up much of the

"Don Reitz11 , A Ceramics M:onthly Portfolio, by Catherine C. Brower. 24 decorations he had done. This new process offered him the chance to experiment and seek accidental effects while firing and cooling. He has turned to salt glazed ware because of a stylistic need.

The following are some of the possible choices he may use while firing: He may paint cobalt on a brick, ro that the pots in that area will take on flashes from the cobalt; he also places pots in odd positions and places in the kiln; he ray also throw a variety of materials into the kiln (this includes such things as wood ashes, feldspar, and fruit - how the kiln is cooled has a great deal to do with his results); he may also use a process called fuming (an example of this is adding stannous chloride at red heat to cause an irrides cent mother of pearl effect).

Pitcher by Don Reitz 25

The following pieces, by John Stiefl, show the contemporary use of the salt glaze process. He has used a variety of decorative techniques, and illustrates a Don Reitz influence. Chapter IV

PERSONAL EXPERIMENTS

The most important thing that stimulated my interest in salt glazing was the natural quality of clay. The natural effects of clay, with no glaze, can be very exciting. I made several pieces without a stain or glaze decoration. The results were very exciting and encouraged me to continue salt glaze experiments because of the beauty of the clay surface was not destroyed. 27

Learning how to operate the kiln and salting process were my first big challenges. After many months of experiments, I finally achieved desired results, such as a nice "orange peel" surface, variation caused by texture, and suitable shapes and decorations that enhanced the process. 28

Decorative techniques and colors were the next challenges th~t

I began to work on. Develo ing stains and engobes were difficult

because salt glazing limits the variety of colors you can achieve.

The f>llowing photoe;raphs show some of the engobes and stain decorations that I used. 29

I tried many types of decorative techniques, stains, textural effects, glaze, engobes, and additives to the salt. Each technique was great fun, but in most cases unreliable.

Texture seems always a successful surface br the ml t process.

Technically it works, but does not aways fit the pot aesthetically.

Texture seems to affect the salt build-up and mottles the surface as to color variation, from light to dark browns, without the use of stains or engobes . Even very subtle textures such as throwing rings will become interesting with variation of color and salt build-up. 30

Other interesting experiments are additions to the salt and changes in the salting process. Varying the amount of salt will change the surface effects. The more salt you use, the thicker the build-up and more of an "orange peel, pocked" surface you will get. I added in some of my firings five to ten percent of borax to the salt and water mixture, which caused a smoother, glassier surface. Ru.tile added to the salt will give a greater variety of color changes from light to dark. Many things can be experimented ·.-;i. th, there is no limit, as Don Reitz has shown us.

The following is a picture vhich shows the use of borax and ru tile to the salt. 31

I did much work with engobes. My first concern was finding a base formula that had a nice texture and remained white after salting. The following base formula seemed the most satisfactory:

Kaolin 50 percent Ball Clay 30 percent Flint 15 percent Borax 5 percent Tin oxide 5 percent

I began working with colors, by devising a chart that used these types of clay: Etoneware (iron), white stoneware, and porcelain.

I added all the colorants available in our studio to each type of clay, in a proportion suitable for the colorant, and then a combin- ation of colorants I felt would produce good effects. Many of the colors were failures and undependable. The results of the ecperi­ ments can be seen on the tile test board that coordinates with the following chart. 32

stoneware Stoneware Stoneware White Stoneware White Stoneware White Stoneware Porcelain Porcelain Porcelain

100 Base+ chromium 100 Base+ 6 Prasodium 100 Base+ l cobalt oxide stain carb. + 4 manganese diox. 100 Base + cobalt 100 Base+ 6 rutile 100 Base+ 4 van. stain carbonate + 3 tin+ l iron 100 Base+ ½ cobalt 100 Base + 4 red 100 Base+ 5 rutile oxide iron oxide +$red iron oxide 100 Base + 3 copper 100 Base + 4 vanadium 100 Base+ 7 rutile + carbonate stain 1 copper carbonate 100 Base + 2½ copper 100 Base + yellow 100 Base+ 5 rutile + 3 OY.ide ochre magnetic iron oxide 100 Base+ 4 crocus 100 Base+ 6 alb~ny 100 Base+ 1 manganese martis red dioxide+ l copper oxide 100 Base + 6 crocus 100 Base+ 7 barnard 100 Base+ nickel oxide+ martis yellow 2 red iron+ 2 rutile 100 Base + 3 magnetic 100 % barnard 100 Base+ 8 rutile + 2 iron oxide black manganese dioxide 100 Base + 2½ manganese 100 %michigan 100 Base+ 5 manganese dwhorla. te dioxide+ 5 iron oxide 100 Base + 2½ manganese 100% albany 100 Base+ l iron oxide dioxide + l copper oxide 100 Base + 4 nickel 100% wrenshall 100 Base+ nickel oxide oxide + 3 copper oxide + 3 vanadium stain 33

Stoneware Stoneware Stoneware White Stoneware White Stoneware White Stoneware Porcelain Porcelain Porcelain

100 Base+ 5 tin oxide 100 Base+ 1 Cuo 4 100 Base+ 8 red iron + 3 magnetic iron oxide 100 Base + 1 cobalt 100 Base+ Cu Co 3 100% barnard oxide+ 1 nickel + 7 rutile

100 Base+ 2 cobalt 100 Base + 5 Cuo 100% Michigan carb. + 5 tin oxide 100 Base+ 3 vanadium 100 Base+ 8 crocus 100% yellow ochre + 1 copper carb. martis red + 1 co. carb. 100 Base+ 7 copper 100 Base + 10 crocus 100% albany carb. + 7 lithium martis yellow carb. 100 Base+ 7 lithium 100 Base + 7 magnetic carb. + 6 red iron iron oxide oxide

100 Base+½ copper 100 Base+ 5 manganese 100 Base + 8 oxide+ 3 iron oxide carbonate red iron oxide ¼ cobalt oxide ¼ manganese

100 Base+ 3 red iron 100 Base+ 5 manganese 100 Base+ 5 Guo oxide+ rutile + 1 dioxide black iron+½ manganese dioxide

100 Base + 8 nickel 100 Base + 8 red oxide crocus martis 100 Base+ 6 Cr 2 03 100 Base + Praseodimium 100 Base+ 8 nickel stain oxide

100 Base+ 2 CaCo 3 LOO Base+ 10 rutile 100 Base + 5 manganese dioxide 34

Stoneware Stoneware Stoneware White stoneware White Stoneware White Stoneware Porcelain Porcelain Porcelain

100 Base + 8 Praesodium 100 Base+ 6 magnetic 200 Base+ 3 chomium iron oxide oxide+ 6 prascodium stain

100 Base+. 6 chomium 100 Base+ 3 vanadium 100 Base + 100 albany oxide + 1 copper carb. + 7 lithium carb. + 1 co. carb. + 6 red iron oxide 100 Base+ 10 rutile 200 Base+ 2½ copper+ 2 200 Base+ 5 rutile cobalt carb. + 5 tin + 3 red iron oxide oxide + 5 yellow ochre 100 Base+ 1 cobalt 200 Base+ 3 copper 200 Base+ 3 magnetic oxide carb. + 2 cobalt carb. iron+ 3 vanadium + 5 tin oxide stain+ 1 cobalt carb. + 1 copper carb. 100 Base+ 6 vanadium 200 Base+ 6 rutile + 4 200 Base+ 4 mang. carb. stain iron oxide+ 2 mang. + l nickel ox.+ 6 diox. + 2½ copper ox. copper ox. + 3 vanadium stain 100 Base+ 2 cobalt 200 Base+ 5 tin oxide 100 Base+ 100 Wrenshall carbonate + 3 mag. iron+ 4 + 1 nickel oxide+ 2 crocus martis red iron+ 2 rutile 100 Base+ 7 magnesium 200 Base+ 4 crocus martis 100 Base+ 100 albany carbonate +½cobalt oxide + 1 co. ox.+ l nickel ox.+ 7rutile 100% Michigan 200 Base+ 5 tin oxide 300 Base+ 2½ mang. diox. + 3 magnetic iron+½ + 4 vanadium stain+ 7 copper oxide+ 3 iron copper carb. + 7 +½manganese+ ½ cobalt lithium carb. oxide 100% Albany 200 Base+ 4 black nickel ox. 400 Base+ 4 red iron+ + 1 iron ox. + 1 copper 5 rutile + 3 mag. oxide iron+ 4 mang. carb. + 6 rutile 100% Barnard 200 Base+ 2 cobalt carb. 300 Base+ 100 albany + 1 + 5 tin oxide+ 4 co. carb. + 1 nickel black nickel ox. 100 Base+ 10 yellow 200 Base+ 7 rutile + 1 crocus martis copper carb. + 1 mang. ciox. + 1 copper oxide 35

The following are photographs of my more successful engobes. I had difficulty in my choice of photographs because so much of the success of engobes depends on its use on a particular piece. It was my objective during my experimentation to maintain the natural mottled surface rather than a more brilliant shiny surface. All of the flllowing tests began with the basic engobe formula: Kaolin 50 percent Ball Clay 30 percent Flint 15 percent Borax 5 percent Tin oxide 5 percent

1 A Stoneware 1 B White Stoneware

100% Base 1% Cobalt Carbonate Cobalt is a good colorant for salt glaze because it r emains colorful. (lA)Stoneware clay was used for this tile, and during the firinc some of the iron and other impurities came through, leaving a greyed blue. (lC) Porcelain is lacking in impurities and leaves a more pure color

1 C Porcelain 36

100% Base 3% Manganese oxide (Mr.02)

Five percent of this colorant should not be used in the glaze because blisters may develop.

2 A Stoneware

2 B VJhi te Stoneware 2 C Porcelain 37

100% Base 6% Rutile (Ti.02) Rutile is impure titanium and contains small amounts of iron and vanadium.

3 A Stoneware

3 B White Stoneware 3 C Porcelain 38

No Base 100% Barnard Barnard is a low-fire clay high in iron . It is ideal for salt glazing because of the availability and economy .

4 A Stoneware

4 B White Stoneware 4 C Porcelain 39

5 Stoneware 100% Base o/ 11~/0 .Magnetic iron oxide 1½% Vanadium stain ½% Cobalt carbonate ·l% Copper carbonate

6 Stoneware 100% Base 50% Albany ½% Cobalt Carbonate ½% Nickel oxide 2% Rutile 40

7 Stoneware 100% Base 6% Vanadium stain

8 Stoneware 100% Base 10% Rutile 41

9 Stoneware 100% Albany Albany is a low-fire clay No base and becomes quite s.iny.

10 Stoneware 100% Base 11 Porcelain 100% Base ½% Manganese dioxide ·}% Mang. diox. 3% "R ed iron oxide ½% Copper ox, 1% Black iron oxide 3% Iron oxide 1% Rutile ½% Cobalt ox. 42

12 Stoneware 13 Stoneware 100% Base 100% Base ½% Copper oxide 7% Lithium carbonate 3% Red iron oxide 6% Red iron oxide ½% Cobalt carbonate ½% Manganese dioxide

20 White Stoneware 100% Base 1% Mang . dioxide 1% Copper oxide 43

21 Stoneware 22 Stoneware 100% Base 4% Vanadium stain 5% Rutile 3% Tin oxide 3% Red iron oxide 1% Red iron o~cide

23 White Stoneware 100% Base 5% Yellow ochre 44

This pot shows the use of engobes. It has a combination of engobes on it.

I feel that this project could have continued. I ,rnuld have liked to continue work with different bases and colorants to achieve a different surface effect, but wanted at this time to keep the earthy quality of the clay. It may have been interesting to use a glossy surface and brilliant colors as well. The follov,ing photographs are modern Grenzhausen ware , which show the use of colored slips and engobes . 45 Chapter V

CONCLUSION

After having experimented with the different forms of salt

glazing, and having researched its development, I have cultivated

a full appreciation of its worth. I feel that salt glazing is one

of the most exciting processes to do. The potter has a constant

involvement with the firing, but the results are so accidental that

opening the kiln is always a surprise.

The values have changed throughout the course of history.

In its early stages, it was used for tiles, pipes, and utilitarian

objects. At present, potters are aware of the artistic worth and

are using the process for decorative and sculptural ware.

The process lends itself to clay; it is a simple, exciting,

durable means of glazing pots. Unfortunately, it also has

undesirable qualities. It is hard on the kiln and kiln furniture,

and also can be a great pollutant.

The tests that I have done have had satisfactory results and

have motivated my interest to experiment further. I have limited myself to a matt, earthy quality in my eneobes, because I wanted

to keep the natural clay quality. /iJ3 a result of my early change in attitude toward more geometric sculptural forms, experiments in a shinier, more colorful engobe would be very exciting to work on. 47

I feel I have gained through my salt glaze experiments a good feelihg for the qualities of clay. Also, a great deal of pleasure due to the nature of the process. I feel that this process has the most value by enhancing the clay surface. The nutural quality I achieved is shown in the picture below. BIBLIOGRAPHY

Barber, Edwin A., Pottery and Porcelain, G. P. Putnam 1s Sons, Knickerbacker Press, 1909. Barber, Edwin A., Salt Glazed Stoneware; Germany, Flanders, England, and the United States, Philadelphia: Penssylvania Museum Press, 1906. Billington, Dora M., The Technique of Pottery, London: B.T. Batsford Ltd., 1962. Binns, C.F., The Potter's Craft, Lancaster: Lancaster Press, Inc., 1947

Blacker, J. F., The A. B. C., of English Sal t .. Glaze Stoneware 2 From Dvvight to Daulton, London: Stanley Paul and Company, 1922.

Brower, Catherine C., •1Don Reitz", Ceramics Monthly. Foster, H.D., Salt Glazes on Structural Clay Building Units, Columbus: Ohio state University, 1942. Garzio, Angelo, "German Salt Glazing", Ceramics Monthly, June, 1972. Haney, W.B., Wedgwood Ware, London: Faber and Faber. Henzhi, Lucile, American Art Pottery, Camden, New York: Thomas Nelson, Inc., 1970. Home, Ruth M., Ceramics for the Potter, Peoria, Illinois: Chas A. Bennett Company, Inc. Lewis, Gresilda, ·A Collector's History of English Pottery, Great Britain: Studio Vesta Lts., 1969.

Nelson, Glenn C., Ceramics: A Potter 1 s Handbook, New York: Holt, Rhinehart and Winston, Inc., 1966. Parmelee, Cullwn w., Ceramic Glazes, Chicago: Industrial Publications, A.L. Friedberg, 1951. Powell, Harold, The Pottery Handbook of Clay. Glaze, a.~d Colour, London: Blandford Press, 1968. Ramsay, American Potters and Pottery, New York: Tudor Publishing Company, 1947. Rhodes, Daniel, Clay and Glazes for the pot:t.fil:, Philade~phia: Chilton Company, 1957. Rhodes, Daniel, Stoneware and Porcelain, Philadelphia: Chilton Company, 1959. Watkins, Lura Woodside, Early New England Potters and Their Wares, United States: Archon Books, 1968. Webster, D.B., The Brantford Pottery, Ontario: University of Toronto Press, 1968.