WMF GLASS
by Ivo Haanstra
Although WMF produced glass for more then 100 years, their period of triumph in glass only lasted from 1926 to 1936. WMF, or the Württembergische Metallwarenfabrik, was essentially a metal works. They started making glass in 1883 when a glass house was built at Geisslingen near Stuttgart.
The company was, and still is, a producer of metal tableware, particularly silvered flatware, and they began by producing their own glass inserts for cruet stands, open salts, cookie jars and similar articles. Glass was never a core business - metal was. The original 1883 glass house was destroyed during the First World War and a new, more modern facility opened in 1922.
At first, production of inserts continued as before, but soon pieces decorated with cut olives and facets left the factory.
The young glass designer Karl Wiedmann perfected the technique of iridized surfaces and the resulting "MYRA"-Kristall entered production in 1926. The vase above is a WMF Myra vase.
The same year also saw the beginning of the first "IKORA" glass. Both types of glass continued to be produced until around 1936, when production of art-glass ceased.
Although production of Ikora glass resumed after the war, the art glass lines never achieved the same quality, or inspiration of design, or marketshare as before, and production was discontinued in the 1950s. Post war glass production focused more on the modernistic designs of Wilhelm Wagenfeld. Finally, in 1984 WMF’s entire glass production ceased.
Little is known about the other glass production at WMF during this time, although it is known that glass based on historic examples was produced until the early fifties: lidded jars, tankards and various drinking vessels with cut decoration. Cut-to-clear pieces in the Bohemian style were also on the program, and these were of such good quality that nowadays identification is only possible if the original paper label is present.
WMF MYRA glassware
Myra is the name given to the iridized glass produced by WMF from 1926. Based on the same techniques used by Tiffany and Loetz, the glassmaker Karl Wiedmann brought it to the production stage after experimentation at the Zwiesel glass school.
The glass is a crystal formulated with silver nitrate instead of lead. The silver gives the glass a rich translucent amber color, but more importantly, it comes to the surface when reduced in the oven.
At the moment when the glass is covered in a thin layer of silver it is etched with iridescent metal salts, resulting in a bluish green golden lustre with a matt finish. As an additional decorative element, some vases were blown out to achieve a crackled surface. When lit from behind, all Myra glass will show a dark honey colour, which is a good method for their identification.
Around 1935 further experiments were made with surface finishes. Instead of iridescent salts, silver nitrate or copper oxide were used for the finish. Silver nitrate gave a greenish iridescence, while copper oxide produced a bright red opaque finish with a golden shine. When this surface was partly brushed off, the silver etched underlying layer came to light and produced metallic blue clouding. Trials using a base of black glass produced an opal blue, known as "Lavaluna" glass. All possible variations and techniques were tried out, but on black glass the result did not look very different from enameled ceramic ware. For this reason, the Lavaluna technique was shelved and never commercialised.
WMF PERLMUTTER glass
The Perlmutter, or Mother-of-Pearl technique was in essence the same process as Myra, except that instead of silver nitrate, a saturated lead glass was used. After reduction in the oven, the lead would come to the surface where it was iridized.
The result is much colder and sterner than the Myra technique. The surface of Perlmutter glass shines greyish blue and pink, and it has a greater transparency.
WMF IKORA glass
Ikora glass was discovered when the factory tried to repair a damaged Myra piece by covering it in clear glass. The effect was very attractive and unexpected, and gave rise to many experiments in combining colours and surface treatments.
When an iridescent outer layer is cased in clear glass it is transformed into a layer of amber coloured bubbles and swirls.
Silver nitrate, which produces a light milky amber to a smoky dark blue, depending on the light, continued to be one of the main colouring agents. The use of silver salts can be said to be characteristic of many Ikora pieces.
Combinations with ruby gold produced a rich red amber color, and when used together with Selenium, a typical yellowish brown would be the result.
The use of several layers of different coloured glass underneath a clear crystal layer gave a particularly decorative effect; the technique was used to make Jade-glass, which imitated the natural colors and structures of Jade. Many different hot fusion decoration techniques were tried out and used in production.
Pieces were sometimes pre-shaped in a ribbed mould before being powdered, so the colouring agent was distributed over the hot glass in a pattern. 
Sometimes pigments were partially wiped off the surface of the glass before further processing. Additional decoration was sometimes achieved by dipping pieces in cold water to crack the surface. The surface would then be covered in a solution of aluminium nitrate. After evaporation on the surface, the aluminium nitrate remained in the cracks which, after being blown out, resulted in a web-like structure of silver white threads.
Copper foil was used in some pieces, and air bubbles were added by dipping the vessel in hot clear glass.
One long necked vase from 1933 for example combines a wealth of techniques. It is decorated between the layers in an orange-red transparent lower casing, overlayed with yellow, pink and opal blue clouds in colourless glass, partial selenium red overlay, preshaped in 8-fold ribbed mould, cracked in cold water, dipped in aluminium nitrate, strewn with silver chloride flecks, clear cased, stand added, free formed and stand polished.
All Ikora pieces, although they were produced in series, were by nature individual and unique. 
The overall shapes were formed by blowing into moulds but the internal decoration varied endlessly.
Apart from obvious glass vessels (salvers, vases, bowls), WMF also made glass jewelry: pieces of Ikora glass cut and mounted in brass or gilt silver mounting. Ikora lamps were made with a foot which was lit from the inside, resulting in a most dramatic lighting effect. Every swirl, colour band or iridized bubble would be caught in the light between the crystal layers.
WMF ART GLASS
WMF glass was made for distribution alongside the other products of WMF, such as flatware and table settings, and was offered for sale in household stores. Other types of art glass were more likely to be distributed in art galleries and gift shops. The emphasis was on production rather than on individual creators, and consequently WMF glass was never signed: a simple factory label was deemed sufficient. These were team work factory designs, although Karl Wiedmann is credited with many of them. Because the decoration was the result of systematic experimentation rather than artist’s one-off pieces, WMF glass has been underrated for many years.
All pieces which left the factory were well finished. You will not find unfinished pontils or eccentric pieces in the production of either Myra or Ikora glass. You may sometimes question the aesthetics, but never the dedication to quality and finishing. Confusion occurs sometimes with other manufacturers who used the same type of techniques of powder decoration between glass layers. Loetz made a type of glass during the same period called Schaumglas, or "foam glass" which includes colour and numerous small air bubbles and is often mistaken for WMF. Monart glass (Moncrieff, Scotland) made similar vessels in the thirties, but their pontils are ground not polished. Schneider in France decorated between clear layers as did Leerdam, but these pieces are mostly signed. And in the sixties the German firm of Peill & Puetzler produced thickwalled crystal pieces decorated in a technique of gold coloured bubbles called "Schleiergrafit" - but these pieces usually carry the "P" factory mark.
If you are looking for WMF glass, you can sometimes find pieces on offer on ebay.
Click WMF Glass to see some examples.
References and Further Reading
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You could also check out our Recommended Books on Glass.
