At the tender age of thirteen Josef Hartwig began an apprenticeship with the sculptor Simon Korn. In his studio, which was equipped in a historicizing and eclectic manner, the sculptor prepared gypsum models for architecture projects that were, among others, commissioned by the municipal building department, thus the young Josef Hartwig came in contact with famous architects such as Theodor Fischer.
Another famous architect would bestow an early and glorious highlight upon Josef Hartwig: In 1897 August Endell entered the studio with a pencil sketch of an ornamental and abstract dragon that was supposed to be decoration of the Art Nouveau facade of the well-known photo studio "Elvira" in Munich. The then just seventeen year old Josef Hartwig was given the task to transfer the idea from the sketch to a three-dimensional structure, in the course of this project Hartwig was given a lot encouragement and helpful suggestions from Endell. The master piece can only be observed on photographs today, as Hitler had it destroyed.
Josef Hartwig studied sculpting at the Munich Academy under Balthasar Schmidt from 1904 to 1906, he managed to pay for his studies by working as an architectural sculptor. He also took classes in architecture, drawing and art history at the academy.
His parent's death in 1906 was a decisive event in the life of Josef Hartwig. He would soon spend several unresting years in various cities, until he settled in Berlin in 1910, where he worked as a sculptor for some eleven years, being only interrupted by the much hated first world war. In 1921 Walter Gropius called him to the Weimar Bauhaus and made him head of the wood and stone sculpting workshop.
In the workshop Hartwig made mural plastics after abstract figurative drafts by Oskar Schlemmer. These works in the staircase of the workshop building were removed by the Weimar 'Bauhochschule' in 1928, as they were regarded as "needless ornaments". The geometrical additive Bauhaus chessboard counts among the best known Bauhaus works of Josef Hartwig.
Josef Harting taught sculpting, geometry, perspective and lettering at the Frankfurt School of Arts, the 'Städelschule', as of 1925, after the Bauhaus had changed its location from Weimar to Dessau. In the following years, Hartwig worked together with important artists such as Gerhard Marcks, Georg Kolbe, Toni Stadler and Richard Scheibe and besides that also made numerous plastic works of his own. Worthwhile mentioning are the figures for a puppet play or an abstract owl made of Veronese marble. His Bauhaus colleague Gerhard Marcks raised a bronze monument in honor of Hartwig's powerful and creative art, by making "Hartwig's chiseling hand" the subject of one of his sculptures.
Besides sculpting, Hartwig also showed interest in restoration: From 1938 up until the end of World War II Hartwig was working as a restaurateur at the Städtische Galerie in Frankfurt, after 1945 he was master of the restoration workshop of the sculpture collection of the Frankfurt Liebighaus. Josef Hartwig died in 1956 at the age of 76.
Cf.: Hartwig, Josef: Leben und Meinungen des Bildhauers Josef Hartwig, Frankfurt am Main 1955.