Two years later, the Accumulatoren-Fabrik Tudor'schen Systems Büsche & Müller, now renamed "Büsche & Einbeck", concluded an agreement with "Siemens & Halske" and "AEG" to establish a joint-stock company, the "Accumulatoren-Fabrik Aktiengesellschaft (AFA)". The demand was booming and turnover reached 3 300 000 marks. In 1891, it established a central research laboratory, where Henri Tudor acted as a scientific adviser. The improvements that he made included the negative plate with scraped-off paste and the unitary plate (1891), the development of new foundry moulds for finer grooves (1895–1896) and a solution to the problem of capacity loss observed on negative electrodes (1895–1896). AFA occupied a leading position on the German accumulator market and AFA shares were quoted on the Berlin Stock exchange from 1894 onwards. AFA changed its name in 1962 to "Varta Aktiengesellschaft".