Petermann concerned himself much more with printing technology, especially colour-lithography. Although they produced many color maps in this way in the 1870s, more and more maps returned to hand coloring, for it then became cheaper than lithography. According to Stams, the Gotha Institute may have produced some 2,500,000 hand-colored maps for all its cartographic products in a decade, or 800 per day! In his last article published before his death, Petermann speaks enthusiastically about the newly developed photogravure, which considerably reduced costs per map while also increasing production speed. In his opinion the 715-sheet Austrian map was probably twenty times more efficiently produced than an engraved version would have been, for its production took only a fifth of the time and a fourth of the costs.