Over the years, the studios had between 12 and 50 employees, including some prestigious artists like Jacques Martin, Bob de Moor and Roger Leloup.

They permitted him to focus on the creation of new stories by handing over some aspects of the artwork, particularly the colouring, which Hergé had never really mastered and which in the 1940s was done by Edgar Pierre Jacobs, and the drawing of decors.

For example, Jacques Martin claims to have introduced a number of burlesque gags that don't correspond to Hergés style of humour.

When Hergé was on a holiday in December 1965, the two main collaborators, Bob de Moor and Jacques Martin, created a fake Tintin page, completely in the style of the master, which they sent to the Swiss weekly magazine L'Illustré.

[1][2] Apparently, Hergé didn't react immediately upon discovering this, but probably preferred let matters stand as they were with this joke, which, according to some,[3] was a true indication of the state of mind of the collaborators who wanted to be more involved in the creation of the adventures of Tintin.

Some doubt exists about Tintin and Alph-Art, however, left unfinished by Hergé at his death and at first handed over to the Studios to be finished by De Moor.

This is a non-exhaustive list of those works where the Studios played a major role, either by colouring, drawing of backgrounds, or by completely replacing Hergé.