The article is based on description and analysis of the outcomes of the experiments proceeded in the years 2004 and 2006 during that the traditional potash production technology has been restored according to written sources from the 17th, 18th and 19th centuries as well as to the experiments already done in Sweden and Poland. The authors present a wide range of chemical analysis (based i. a. on powder X-ray diffraction and XRF spectrometry) of produced spruce, beech, fern and oats straw ashes, raw and calcinated potash and emphasise its importance for the study of the history of glassmaking in the Central Europe. The most important conclusions are: differences of chemical composition between beech, spruce, fern and straw potash were rather substantial (especially higher content of CaO, SiO2, MgO, MnO and P2O5 in spruce potash and high content of SiO2, P2O5, SO3 and Cl in fern and straw potash). Burning ferns and straw for ash is much more efficient, however, especially the use of fern, as proved by the experiment, was complicated by the impossibility to obtain greater volumes of the plant in the past. The experiments have also shown that the burning temperature of wood as well as composition of soil on which the plant had grown influences the chemical composition and quality of potash; finally calcination had only inconsiderable influence on the purity of obtained product.