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~~~~~~~ A good number of the blue and grey steins made since World War I that are thought of as "salt glazed" really aren't. They actually have modern glazes that are safer to use and more environmentally friendly. Do you know the difference? Can you identify a true saltglaze? Well, if not, let me show you how, but first, a little history. A LITTLE HISTORY The production of true stoneware goes back to the early 14th century, when for the first time, the kilns could be brought to a temperature sufficient to cause vitrification. Vitrification is when the porous clay actually melts into a non-porous mass. This transformation from clay to stone occurs at about 1,200 degrees centigrade, or 2,200 degrees Fahrenheit. By introducing salt into the kiln at the height of the firing, just after vitrification has taken place, a hard glaze that is actually a type of glass, a sodium-alumina-silicate, is formed on the stoneware surface as the sodium in the salt and the silicates in the clay chemically combine. A proper glaze requires 5 kg, or about 10 lbs. of salt per cubic meter of kiln space. The salt glazed stoneware is impervious to all liquids except hydrofluoric acid. Before the development of stoneware, ceramic vessels had to be given a glaze, usually a lead glaze, so that liquids could not seep through their porous walls. Because stoneware is vitrified and not porous, it does not actually require a glaze, but a glaze is added for aesthetic purposes, and of course it makes the job of cleaning them much easier. Just as porcelain was developed in China centuries before it would be produced in Europe, so it was with stoneware. Stoneware was being produced in the Middle East and China, long before the proper kilns were developed in Europe. An almost, or proto-stoneware (figure 1) was being produced prior to 1200 and is sometimes found with a brown, iron wash, which some think may have been an attempt to seal the porous nature of the material. However, because the pieces are found with the wash applied externally, only to the upper portion (figure 2), nearly as often as they are found with complete coverage, I feel that in addition to its questionable effectiveness, it may have been an attempt at giving some individual style to a boringly repetitive product.
A true stoneware (figure 3) was developed around the first quarter of the 14th century and by 1350 most kilns along the Rhine were turning out true stoneware. Of course, as soon as a canvas was available man had to decorate it and saltglazing along with new body styles, under glazes, and applied decor (figure 4), followed closely on the heels of stoneware development.
Cut and stamped decor was added around 1500 and cobalt oxide was added to the available decor options in Siegburg and Frechen about 1525. Little changed over the next sixty years, but in 1583 the civil war of the Truchsess Apostacy broke out and the Siegburg potter's district of Aulgasse was destroyed. As a result, between 1583 and 1588, the Siegburg and Freschen potters emigrated to the Westerwald. The Siegburg potters settled in Grenzau and the Freschen potters in Grenzhausen. At approximately the same time, during the Revolt of the Netherlands (1566-1609) they were joined in the Westerwald by the potters of Raeren. This was the beginning of the Westerwald stoneware industry that we are familiar with today. Around 1590-1600 they produced the jug in figure 5. Around 1650 manganese appeared in conjunction with cobalt as a decor option, but its use was short lived and was discontinued for some reason about 1680. It would reappear once again in the final quarter of the 19th century.
So, who discovered saltglazing, and when? Well, we really don't know for sure, but it probably occurred in either Siegburg, or Freschen. There are several theories as to where, when and how, but most agree it was serendipitous. By combining a couple of the theories, here is how it might have happened. For saltglaze to be discovered, two things had to occur; one, you had to have a fire hot enough to vaporize salt and two, salt had to somehow be introduced into the kiln. Back in the 13th and 14th centuries there were no labor unions, but craft guilds saw to it that their members were protected much like labor unions are supposed to today. Wood cutters didn't make pottery and potters didn't cut wood, so if you were a potter and required a given quantity of wood each year to fire your kiln, you purchased your wood from a broker who probably lived in Cologne and who arranged to have the required amount delivered to you on an agreed upon schedule. It was neccessary to dry the wood for 6 months before it was ready for the kilns. The firing season was regulated and took place between the end of May and mid-November. On the average, each potter did four firings a year. This meant that there was a firing every six weeks. Each firing consumed just over 32 cubic yards of wood, or a pile 10 ft. wide, 10 ft. long and 10 ft. high. Even in the 13th and 14th centuries wood was scarce. All of the forest lands were controlled by someone with a title in front of their name and the common man used peat for heating and cooking purposes. As a result, the potters took whatever wood they could get and in the west, in Siegburg and Freschen, they were forced to use a certain amount of salt saturated drift wood as fuel for their kilns. Small bits of ash would be carried into the kiln by the flames and deposited on the surface of the contents where small spots of glaze would form. It didn't take long to put two and two together and an industry was established that would dominate the ceramics industry of Western Europe for the better part of the next 500 years. We tend to think that most factories made beer steins as their sole product, but beer steins were just a small part of most factory's total output. For instance, J. A. Knödgen of Höhr, founded in 1865, made gepresste kännchen, or "Regensburg" type steins along with utilitarian table ware such as coffee pots, butter dishes, candle holders, etc., while his major trade was in urinals and sewer pipes. Having said that, the following eight factories produced the majority of the quality, salt glazed beer steins manufactured between 1862 and 1900. Each of these factories had their own style and if you look closely, each style can be recognized with a little practice; well, maybe a lot of practice. A number of other factories, among them, J. W. Remy and M. Girmscheid, also produced salt glazed beer steins, but these steins were a minor part of their total beer stein production.
The factories are: Simon Peter Gerz, founded 1862 in figure 7; Reinhold Hanke, founded 1868 in figure 8; Merkelbach & Wick, founded 1872 in figure 9; Borho, Zinkl, Fritz Thenn, Regensburg, founded 1874 in figure 10; Schön, Borho, Hauber & Reuther, Freising, founded 1876 in figure 11; Marzi and Remy, founded 1879 in figure 12; Reinhold Merkelbach, founded 1882 in figure 13 and Dümler and Breiden founded 1883 in figure 14. THE PROCESS The stoneware clays in the west of Germany are a white-yellow when they come out of the ground. The clay is finely ground and screened to remove any impurities. The clay is then mixed with quartz and fluxing agents in the following proportions, the exact percentages depending on the actual recipe used by any particular factory: clay, 30-70%, quartz, 30-60% and fluxing agents (lime, magnesia, alkalis) 5-25%. Once the clay has been prepared it is mixed with water until it is the proper consistency. Up until 1865 everything was turned on a wheel and decorated with the cut, stamp and apply method. In 1865, the plaster press mold was introduced to the Westerwald and while the bodies were now made in molds, the decor was still cut, stamped and applied. In 1872, Merkelbach & Wick made a giant leap forward and began applying the decor in the mold (see figures 15 and 16) and finally, slip molding came online with the advent of ivory stoneware in the late 1880s.
Once the steins were out of the molds, cleaned, marked and dried, it was time to decorate them. The blue, purple, or sometimes green under glaze found on salt glazed steins is called "smalt." It is comprised of silica, potash and a coloring agent such as cobalt oxide, or manganese dioxide mixed with enough water to flow properly.
SURFACES AND COLORS Now that the kiln has cooled, we can remove the contents and examine it. One of the steins that may have come out of the kiln, and has already been to the pewterer, is the 2.0 liter piece in figures 18 and 19. If we look closely at the surface we find that where the clay was exposed to the sodium oxide fumes, the surface is textured and looks somewhat like an orange peel (see figure 20). This is a sure sign that this is a salt glaze surface. It looks the way it does, because the larger silica particles do not melt completely, resulting in a bumpy, or reticulated surface where the melted silica runs down and collects in the recesses between the unmelted silica mounds. The orange peel pattern is much larger in figure 21 than it is in figure 20 and this is due to larger size particulates in the clay. Either the clay wasn't sieved as well, or perhaps sand was added to the mix to get this larger pattern.
You will also note that the manganese areas around the face in figure 20 are smooth and shiny. Aren't these areas saltglazed also and if so, why is there no orange peel texture? The simple answer is no, they are not salt glazed and here is why. A salt glaze surface requires a chemical reaction between the silicates in the clay and the sodium oxide to form a glaze. Where the clay surface is protected from contact by the sodium oxide, no glaze can form. Remember, the colored glazes, or smalt, are composed of silica, potash and a coloring agent which is a simple recipe for colored glass. During the firing process, the smalt becomes glass, fusing to the surface and in the process, uses up all the free silica in the smalt leaving nothing for the sodium oxide to react with.
Thus, the sufaces of your blue and grey salt glazed steins are completely sheathed in glass, but two different types of glass, formed in two completely different ways. Additionally, the color and/or texture of the cobalt and manganese glazes can be used to identify the factory that produced the piece, especially the manganese which can range from pink to black. To cover that subject completely would take another large article, so I am only going to give you two examples, one from either end of the scale. Figure 22 represents the top end of the scale and figure 23 the bottom. Figure 22 is a close up of a Merkelbach & Wick stein and figure 23 is from a Reinhold Hanke stein, both are ca.1875.
During their first few years of operation, Merkelbach & Wick produced colored glazes that were, in a word, "luscious." These glazes used minimal coloring agent and were tranparent, so that the clay underneath showed through, giving the glaze a subdued, smoky appearance. The Reinhold Merkelbach factory used similar glazes early in their operation, but only for a short period of time. Reinhold Hanke went the other direction and opted for more opacity by adding clay to their smalt recipe, giving their glaze a gritty and often matt appearance. The same look is found on Regensburg pieces, which is no surprise, seeing as the Regensburg factory was founded by Maximilian Borho, an ex-Hanke employee.
Figures 24, 25 and 26 show a 2.5 liter stein by Reinhold Hanke ca.1890-1900. The stein is ivory stoneware and is decorated simply, with only cobalt and manganese under glazes. However, instead of a salt glaze, it has a typical modern glaze made of glass frit, a flux of some kind and water. This is a low temperature glaze that doesn't depend on a chemical reaction with the clay to form the glaze so the clay surface is left perfectly smooth as seen in figure 26. So, even if the stein is blue and grey, but the entire surface is smooth, without orange peel, it is not salt glazed. REFERENCES An Illustrated Dictionary of Ceramics Alt Höhr Grenzhausen German Stoneware 1200-1600 Regenburger Steinzeug Westerwald Steinzeug 1600-1914  to Table of Contents. |
