M. Járó - L. Költő szerk.: Archaeometrical research in Hungary (Budapest, 1988)
Analysis - JÁRÓ Márta, GONDÁR Erzsébet: Mediaeval membrane threads used for weaving and embroidery
Hernming remarks that in the case of membrane threads used for silk fabrics in Palermo the strips made from gilded gut were wound around the thin flax yam with wide spaces in between [11]. 3 3. GÜding and plating with silver Based on a mediaeval label attached to membrane threads (aurum battu tum) it is widely held that gold foil ("hammered gold") was applied to the membrane [1,2]. According to Petraschek— Heim gold foil or gold powder was used for güding [12]. The researchers unambiguously state that apart from a few exceptions the membrane threads have lost their metallic appearance, have become worn and acquired a brownishblackish taint. There are only few descriptions of the method of gilding or plating with silver that are based on examination data. Relying on Harz's, von Miller's and Brücke's results of examination under the microscope Book states that gUding took place by applying silver and subsequently gold onto the peritoneum, (the membrane that lines the cavity of the abdomen of cattle) [13, 14]. The presence of a silver layer under the gilding (in almost every case) was proved by the authors' [15] and Darah's [16] tests. From the literature, therefore, it can be concluded that the membrane thread has a finer and a coarser variety, there are however, confronting views on their origins (sources of supply and the venue of production). The threads were made by plating animal gut with silver or güding the silver coating afterwards, probably using gold foil for this purpose . This could offer an explanation as to why the threads have become black (silver being corroded underneath the worn gold), but does not provide sufficient insight into why some membrane threads have retained their original shine as opposed to the majority, which have lost their gilt. 4. Aims of the investigation A detailed examination of membrane threads was initiated by the uncertainties surrounding their origins and spreading as well as the lack of information on how they were actually prepared. Our aim was to find out if — beyond the two major types described in the special literature (fine, richly gilded and coarser, poorer quality wound around flax yarn) — further subgroups could be established, and if so, whether they could be assigned to specific places and dates. In addition to the results of a critical analysis of style, the above knowledge could provide art historians with a further proof in the dating of textiles woven from or embroidered by membrane threads as well as for the confirmation of their place of origin. 5. Experimental In the first phase of our investigation described here, a morphological examination of 47 pieces of textile dated mostly to the 14th—16th centuries, most of them belonging to the Museum of Applied Arts in Budapest (weavings and embroideries), took place. Using microscopic and analytical methods an attempt was made to leam how the gilding was carried out.
