What is gelbe Lösche?

Elisabeth Singer’s article on pavises in the Vienna Zeughaus is excellent but she wrote in ordinary Austrian German not chemical jargon. While the grammar is simple, the words include a few informal terms.

Direkt auf den mit einer gelben Lösche abgebundenen Grund wurde abschließend die Randbordüre gemalt, die von einfachen nebeneinanderegesetzten, farblich kontrastierenden Bändern bis zu prachtvoll durchgestalteten, gerankten Blatterornamenten oder Schriftbändern mit weißer, gelber oder schwarzer Binnenzeichnung reicht. Die am Institut für Farbenchemie, Akademie der bildenden Künste, durchgeführten Bindenmitteluntersuchungen ergaben – wie schon Textur der Oberfläche und Lösungsmittelproben vermuten ließen – daß es sich bei der Bordüre um eine Malerei in fetter Eitempera handelt.

Elisabeth Singer, “Die Setztartschen des Wiener Bürgerlichen Zeughauses: Geschichte, Bedeutung, Konservierung.” In Robert Waissenburger (ed.), Studien 79/80 aus dem Historischen Museum der Stadt Wien. Wiener Schriften Heft 44 (Jugend & Volk: Wien and München, 1980) pp. 63-90, p. 86

I would render that in English as:

Direct on the ground, which was bound with a yellow Lösche, the border bands were painted last. They range from simple bands of contrasting colours placed next to each other to ambitiously carried out floral ornamentation or bands of writing with white, yellow, or black interior drawings. The analysis of the binder at the Institute for Pigment Chemistry, Academy of the Applied Arts concluded – as the teture of the surface and tests with solvents already allow one to suspect – that the painting of the borders was carried out in a fatty egg tempera.

The trouble with natural language and everyday shop talk is that it is not very precise or standardized. Someone in the next studio or the next village or the next trade might call the same thing by a different name or a different thing by the same name. If you are not a native speaker, these terms are even more difficult to understand. This is why Carl Linnaeus created scientific names for animals, and Antoine Lavoisier created scientific names for elements and compounds, that would be understandable to an animal feeder at the Berlin Tiergarten and a zoologist in Lisbon. So what did Singer mean by yellow Lösche?

White grounds for painting traditionally consist of a calcium-based mineral and an adhesive such as hide glue or gum arabic. Simple whitewash (a calcium mineral and water, sometimes with traces of sticky substances to help bond it to the surface) is not hard and stable enough, and lime plaster is caustic so people only work with it if they need a watertight surface. One of my professors who spent a summer mixing lime mortar in an Italian harbour remembers a late-night trip to a pharmacy to treat the chemical burns from the lime in his torn and dusty overalls.

In Europe panel paintings are usually painted on a layer of gesso made from chalk and hide glue or gypsum and hide glue. These create a smooth, hard, sensually soft layer which is somewhat water-resistant. Medieval texts such as On Divers Arts and the Libros del saber de astronomía say that shields are made similarly to panels for painting, and in modern Dutch and German “shield” and “sign in the street” have the same etymology.

German Wikipedia associates Lösche with powder and with black carbon compounds and oxides. Coal dust can be Lösche, as can hammerscale from a forge, and the cinders from burning coal. None of these sounds like a suitable material to paint, or something that would be called yellow.

Bronsen @bronsen@chaos.social of the Institut für angewandte Futuristik suggested Löschkalk, also known as calcium hydroxide and Ca(OH)₂. That does not seem much like any of the other kinds of Lösche but I see a possible connection. When you put out a fire in Austria you löschen it. And one name for calcium hydroxide is slaked lime because it has been mixed with water until its no longer as hazardous as quicklime (you make lime by burning limestone to remove some of the oxygen and break up the structure). People used to paint on lime plaster which consists of sand, water, and lime. Slaked lime is a pale powder but its shade can look more like weak lemonade than chalk. So while I wish I had access to the original report, I think that slaked lime is a pretty good guess as to what Singer meant. She could also have meant other calcium minerals which had been dissolved in water. Do any of my gentle readers know a good dictionary of art-technological terms in German?

(scheduled 10 November 2024)