In the course of research into various methods of metal coloration, the book by Hugo Krause proved to be particularly informative and helpful.
The chemist dealt with this little-explored branch of metal science and wrote a practical textbook aimed at practitioners. He seems to have spared no effort and carried out a large number of the coloring methods himself, using formulas from other books – as well as technical and patent specifications – in order to make the selection of well-functioning processes that were finally included in his book. Worthless methods, which, for example, do not produce a firmly adhering or only a "lean" coloration, were omitted or supplemented with suggestions for improvement. Hugo Krause's book is characterized by the combination of observations and practical experience with explanations of chemical processes and key topics. As a practitioner, one receives tangible instructions, whilst at the same time never being under the illusion of being able to implement and understand them successfully on a first attempt. In addition to clearly structured contents, he formulates in various clear ways that certain processes of metal coloration are not easy to classify. Regarding corrosion protection by metal coloring, he wrote: "The chemical processes which lead to the destruction of metallic materials by corrosion and which can also be used to produce metal colorings are of a very complex and complicated nature."
The book by Hugo Krause is also on the shelf of the art Library of the Sitterwerk Foundation. There it is located in the direct vicinity of a materials collection in which many variants of colored metal samples are stored and made accessible. The samples come for the most part from the production of the neighboring Art Foundry St. Gallen, where in the Patina Workshop the craft of metal coloring is being nurtured and further developed.