(1928, Brno – 1999, Praha) Painter, sculptor, graphic artist. From 1952 to 1957 he studied at the Prague Academy of Arts, Architecture and Design (under Josef Novák and Alois Fišárek). He was a member of the Concretists’ Club. His early work focused on applied art, fabrics, toys and puzzles. Later he turned his attention to monotypes (printing everyday objects such as matches or razors) and then to his first “variables” (1964, 1965) – i.e. sculptures whose shape and configuration were flexible and could be deliberately altered. In the mid-1960s he produced a series of variable reliefs made from coloured cork stoppers, wedges and rods. In the 1970s Kratina’s focus shifted from wood to metal, whose mechanical and kinetic properties were more suitable for constructing his variables. Initially he worked with ready-made prefabricated metal pieces, though eventually he began commissioning bespoke-made components. He began with iron, later exploring the possibilities of alloys – brass and duralumin. As his choice of materials evolved, so did the appearance of his works. Reliefs gave way to free sculptures with tower-like or rod-like shapes. Kratina’s metal sculptures are perfect in form and pregnant with meaning, reflecting the artist’s rational thought processes. On the other hand, he created kinetically variable pieces with the intention of encouraging the viewer to engage in play.