Testalin
Testalin is a chemical substance that has been used to impregnate stone, especially sandstone and artificial stone, as well as other products with cement as a binding agent since the 19th century . The product was manufactured by Hartmann & Hauers in Hanover .
In successive process steps, the stones were soaked in an alcoholic solution . With a solution of clay acetate , insoluble oleic acid clay is then formed , which prevents water from penetrating the stone.
The Polytechnic Journal wrote in 1895:
“Porous building materials have the unpleasant property of gradually becoming crumbly as a result of water absorption and subsequent freezing in winter; As a result, softer types of stone often appear completely weathered on the surface, with some sandstones one layer after the other falls off, provided they are parallel to the outside. The porosity also has the disadvantage that dust and smoke stick extremely firmly on the house facades as they are sucked up by the penetrating water, so that the surface can no longer be cleaned by simply washing it off. The inconvenience can be eliminated by painting with oil , but this means will not be used in beautiful stone architecture. A method invented by Hartmann and Hauers in Hanover now aims to relocate the pores of the building block, from the surface to a shallow depth, in such a way that water is prevented from penetrating without the stone-like character being lost as a result; on the contrary, there is still an animation of the color tone. The agent used, called testalin, consists of two liquids that are applied one after the other to the stone using a brush: an alcoholic solution of potash oil soap and an aqueous solution of acetic alumina . If the two liquids are experimentally poured together, a lumpy mass of clay- oil soap precipitates , which is yellowish in color, completely insoluble in water and of a tough, rubbery consistency, without sticking to the fingers. This mass is also what forms in the pores of the stone. One first brushes with the soap solution, with particularly soft rock also repeatedly; Once it has moved in - after 2 to 3 hours - the clay coating follows, the clay oil soap is now deposited in the rock pores.
By examining the process on a small scale, we could see that the color of the stone is enhanced by the paint, and further, what seems to us to be the main thing, that the material has become completely water-repellent; Water flows off as if from an oiled surface, while the unpainted areas soak up immediately. From practical experience with the new stone preservative, Dr. Glinzer in the Deutsche Bauzeitung : The Hamburg town hall was treated with testalin; after almost a year the accumulated dirt, soot and dust, since it had not penetrated into the pores of the rock, could for the most part be removed completely simply by hosing down with a hose, the rest by brushing with water.
Testalin costs 60 pounds per kilo. According to the manufacturer, the paint for the square meter is about 20 pfennigs of material. The product can be obtained from the Rheinische Glasindustrie in Heidelberg, which has taken over the representation for southern Germany. (Badische Gewerbezeitung.) "
Footnotes
- ↑ unbek .: Stone preservative "Testalin". In: Polytechnisches Journal . 297, 1895, Miszelle 5, pp. 119-120. Digitized text from the Polytechnic Journal is licensed under the Creative Commons by-nc-sa 3.0 license . Rights holder: Humboldt University of Berlin, Institute for Cultural Studies.