Frengen can't be catalogued in one style or direction. He calls his technique and philosophy a "unique positive pyronism". It is a reference to his unique technique to make his work voluminous with ashes and fumagine. This way, his work gets more living and organic.
In most of his works a small, but not unimportant detail can be changed by the viewer. By doing this, the artist breakes a taboo and confronts us with our freedom and our responsability.
With exhibitions in Belgium, The Netherlands and the US, Frengen's unique work is apreciated by many people.