His working process focuses on the exploration of light and space using a variety of media. A painter by origin, his work developed over the years into a physical and mental research of the constitutes of painting and its perception, embracing architecture and the essence of light. Under the premise that light paints the world, his works can be described as painted objects rather than paintings, where physical yet ephemeral qualities of light (as material) and space can be reflected upon; aspiring to a reviewed perception of what is and aiming to engage the viewer in this process.

As curator Joao Ribas writes in his text Move closer – Look awry (2010, LOOK AWRY, Kunstnernes Huis, Oslo):
`` This phenomenological confrontation—part of Tilman’s assimilation of Minimalist sculptural practice---is part of his work’s openness to contingency and context. Tilman’s attention to both becomes a primary concern in his site-specific, architectural arrangement of paintings, challenging conceptions of the autonomous artwork—the fetish object of modernism---with the ethos of installation art. Tilman’s serial works, for example, are serial appearance but not in effect, as the rhythmic qualities color and changing light give a unique quality to each of the repetitive forms. The paintings are thus objects in a state of perpetual change, subject to transformation by qualitative and quantitative variations of their spatial character, of their inhabited space. In this sense, Tilman’s paintings ask to be looked at the way one actually approaches the shifting perception of the physical world. The viewer of invited to peer below, underneath, aside, and sometimes literally inside a painting. Tilman attracts that simple yet rewarding curiosity: the playful impulse to look inside a box or around a corner. An exploratory dimension is thus added to the act of looking, a physicality supplementing the unfolding of apperception traditionally associated with abstraction. To perceive becomes to participate. As Merleau-Ponty suggested, “the perceiving mind is an incarnate mind.” Tilman’s work seems to cleverly ask apropos of abstract painting: “Where do you stand? What is your position?” After realizing several large scale in-situ installations (Vienne (FR), Lyon Biennale Resonances (FR), Toowoomba (AUS), Braine- lAlleud (B)), which he labels as artitectures as part of an expansive painting process, he - in collaboration with Canadian-born artist Cora von Zezschwitz – launched the project INFINITE VILLAGE in 2017.
Under the title iNFINITE VILLAGE both artists created large in-situ installations in Venice (IUVA, (2017), Campo dei Gesuiti (2018)), Biennale de Grenchen (CH), (2018), Eglise des Célestins, Avignon (2018), A Farm, Ho Chi Minh City (Vietnam, 2019) and M-17 Art Center, Kiew (UA, 2019). MANIFESTA 13 Marseille/Paralleles du Sud (FR, 2020)
His work is shown extensively since 1992 in Europe, United States, Australia and Japan.
Besides his artistic career he also was artistic director and co-founder of CCNOA (Center for Contemporary Non-Objective Art (1999-2010) in Brussels and currently runs his privately-run art space DAC (Dolceacqua Arte Contemporanea) in Italy. He also was director of Petra Bungert Gallery, New York (1995-1998) and founder of H 29 an artist run space in Brussels (2004-2009). As curator he organized about 40 exhibitions (Europe, United States, Australia and New Zealand)

Tilman lives and works currently in France and Italy