Stiasny test

Description

A chemical test designed to determine the type of vegetable tanning agent used in tanning a leather. It consists of boiling the specimen in a solution of formaldehyde and hydrochloric acid, which causes any condensed tannins present to be completely precipitated. while any pyrogallol tans remain in solution. The test solution is obtained by extracting a fragment of the sample (a piece 4 by 4 mm) by refluxing, for 4 hours, first in a 50% aqueous solution and then equal volumes of 6N hydrochloric acid, acetone and water.

Resources and Citations

• Matt Roberts, Don Etherington, Bookbinding and the Conservation of Books: a Dictionary of Descriptive Terminology, U.S. Government Printing Office, Washington DC, 1982