The businessman Christian Zacharias Gräbner founded a small manufactory on June 18th 1777 after receiving authorization by Duke Karl August and had financial problems right from the start. Gräbner still managed to employ the designer Senff (also named 'Senfft') as well as Johann Lorenz Rienck from the town of Eisfeld in 1781 who actually worked in the factory until 1800, however the financial problems increased and it was obvious that Gräbner was unable to pay back the loan he had received from Karl August. The Duke in 1782 took over the small business and put it under the leadership of his private secretary Friedrich Johann Justin Bertuch who managed to solve some of the financial problems but reported that the factory was doomed if they were not able to find an expert in porcelain production.
So the Duke employed a porcelain expert with the name of Franz Josef Weber from the town of Höchst in 1784 and after just one firing the new director was able to present much better results after having changed the clay and improving the glaze. Soon the small factory was fully optimized and able to produce items in continuous quality so the Duke then rented the factory to Gotthilf Greiner in 1786 who put the small business in the hands of porcelain expert and decorator Johann Siegel. After being successful for some time the factory was in 1792 rented by Friedrich Christian Nonne who also rented the factory in Volkstedt from 1767 until 1797. For the Ilmenau factory, the period from 1792 until 1808 can only be described as the most successful period as they produced items similar to Wedgwoods so-called 'Jasperware' which sold extremely well.
 : Ilmenauer Porzellanfabrik Nonne & Roesch (1808 until 1836)
Around 1807 Nonne finally decided to take over the factory completely and so he teamed up with his son-in-law Roesch and the newly-founded company bought the factory from the Duke in 1808. The success soon faded however after Nonne died in 1813 but Roesch managed to continue until he was finally forced to sell the business in 1836.
 : Ilmenauer Porzellanfabrik G.m.b.H. (1836 until 1930)
Over the next years the factory often changed proprietors and never really was able to regain its former status; in fact it was short before bankruptcy in 1870 until advisor of the chamber of commerce Stücke finally invested the enormous amount of 450,000 Reichsmark in a newly founded stock corporation. He also introduced a new director with the name of Gottlob Morgenroth who run the company until 1874 when he was replaced by Hering who specialized on brocade decorations that proved so successful that the company had to open a subsidiary in the former weaving mill of Schmidt & Reinhard in the 'Stadtilm' part of Ilmenau; the whole factory employed a workforce of around 500 people in the year 1900.
Hering remained director until 1902 and was then replaced by Theodor Albrecht who in 1910 introduced the complete electrification of the factory after installing an own power station. The year 1912 then saw the factory close for six weeks as the workers demanded a pay increase. The war years propably were the reason for the cutback in employees because the number of 500 workers employed in 1913 dropped to a mere 250 in 1916 and the factory was massively modernized in the years 1919 and 1920; around that time the first 'IPM' marks including a hen (more on that later) were introduced. But after the US stock market crash in 1929 the business was confronted with various problems and this resulted in the complete closure of the factory in 1930, making all 350 employees redundant even if the board of directors still remained operational and held nearly all assets.
 : Ilmenauer Porzellanfabrik Graf von Henneberg A.G. (1930 until 1949)
Various discussions followed and after a few members of the board resigned it was decided to continue under a new name and leadership. It should be noted that the name 'Graf von Henneberg' (Duke of Henneberg) was chosen for historic reasons: the town of Ilmenau had formerly been part of the ducy Henneberg and the previous company had already started to use the hen as part of their mark. There was no Henneberg family member involved as is confusingly claimed by some sources, their information is probably based on the mix-up of facts and dates regarding the Porzellanfabrik Henneberg & Co. located in Gotha that was run by Henneberg family members.
Anyway, even if work continued with a massively reduced workforce it still took the members of the board until 1934 before they finally decided that Emil Lentner would be the new director. Under his management the company slowly recovered and in 1937 already employed 250 people again; nearly the same number of employees remained after the war as the records show that a total of 255 people worked for the company in 1949.
 : V.E.B. Henneberg Porzellan Ilmenau (1949 until 1990)
Shortly after nationalization the factory advanced to a so-called 'Vorzeigekombinat', a showpiece of socialist productivity that supplied the state with high-quality goods. For example the parliament of the former German Democratic Republic had its seat in the infamous 'Palast der Republik'; the whole complex included various smaller restaurants and of course had a special set for foreign visitors. All tableware used in the building was supplied by the 'V.E.B. Henneberg Porzellan' and each restaurant had its own unique design.
Even if the factory had been constantly modernized over the years it soon became obvious that the premises were far too small and in 1970 a new factory was planned in the 'Eichicht' part of town that was then taken into operation in 1973. The new factory was known as the 'Neues Porzellanwerk Ilmenau' (short 'NPI') and also operated as supervisory office of the V.E.B. Kunstporzellan Ilmenau until the 'Kunstporzellanwerk' closed in 1976.
 : Graf von Henneberg Porzellan G.m.b.H. (1990 until 2002)
After German reunification the factory was modernized between 1991 and 1993; this was followed by a second modernization step between 1996 and 1997 and as the financial situation was not so good, the company had applied for restructuring aid from the European Union (file number C36/2000) which was granted. On 28 August 1998, the factory was sold to Rolf Frowein, a former manager of the 'Thuringia Industriebeteiligungs G.m.b.H. & Co. K.G.', but problems arose with the loan from the European Union.
In September 2001 the second main creditor represented by the 'Thüringer Aufbaubank' canceled their loan and the company had to pay back over 5.9 million Euro; the bad news was then followed by a letter regarding the fact that with date of October 30th 2001 the restructuring aid from the European Union had also been canceled. That was too much for the 'Graf von Henneberg Porzellan G.m.b.H.' and the company had to file for insolvency. Proceedings were opened on November 1st 2001 and even after an investor from Austria in February 2002 still showed interest in the factory, the whole company was liquidated.
 : Neue Porzellanfabrik Ilmenau G.m.b.H. (2002 until ...)
It seemed that Rolf Frowein did not want to give up easily. He founded the 'Neue Porzellanfabrik Ilmenau G.m.b.H.' and took over the 'Graf von Henneberg' name and assets, completely re-structuring the factory. Large parts of the factory were offered for sale or rent, but production continued. On May 1st 2002 Mrs. Heike Simon founded the 'HERO Design' company which is the factory outlet for 'Graf von Henneberg' products; 'HERO Design' also uses the Henneberg web address.
For further information on why the town name is sometimes written as 'JLMENAU' even if it actually is 'ILMENAU', take a look at the vocabulary entry consonants and vowels.
Dating the marks showing the full Henneberg coat of arms is very difficult and a small help is the fact that those versions with the peculiar shift in the spacing of the letters 'LM' in 'JLMENAU' are the older ones. However, one can not be sure about the periods in which the company used 'Germany' or 'Made in Democratic Republic' as they sometimes simply used the '(Made in) Germany' addition even between 1949 and 1990.