Keim's process is a technique of fresco preparation and painting intended to maximize the lifetime of the finished work. The process, as reported in 1884 at the Royal Society of Arts in London, was created by chemist and craftsman Adolf Wilhelm Keim of Munich, as an improvement on the earlier "stereochromy" technique of Schlotthaner and Johann Nepomuk von Fuchs.
The process
Keim's focus on the careful preparation of the painting ground was the result of his study of older frescos and their state of preservation. Keim reportedly labored for twelve years to refine his process.
References
Keim's process Wikipedia(Text) CC BY-SA