Although multi-touch applications and user interfaces have become increasingly common in the last few years, there is no agreed-upon multi-touch user interface language yet. In order to gain a deeper understanding of the design of multi-touch user interfaces, this paper presents semiotic analysis of multi-touch applications as an interesting approach to gain deeper understanding of the way users use and understand multi-touch interfaces. In a case study example, user tests of a multi-touch tabletop application platform called MuTable are analysed with the Communicability Evaluation Method to evaluate to what extent users understand the intended messages (e.g., cues about interaction and functionality) the MuTable platform communicates. The semiotic analysis of this case study shows that although multi-touch interfaces can facilitate user exploration, the lack of well-known standards in multi-touch interface design and in the use of gestures makes the user interface difficult to use and interpret. This conclusion points to the importance of the elusive balance between letting users explore multi-touch systems on their own on one hand, and guiding users, explaining how to use and interpret the user interface, on the other.