Supersaturation of wine with dissolved tartaric acid is an essential requirement for crystallisation of potassium bitartrate and can be thought of as the driving force. Nucleation must occur, however, before potassium bitartrate crystals can grow and precipitate out of solution. In recent years, wine additives capable of inhibiting potassium bitartrate crystallisation have been commercially available. In this review, the established mechanisms involved in crystallisation are discussed, as they are essential for correctly interpreting the inhibitory effect that wine colloids and additives, such as mannoproteins and carboxymethylcellulose, can have upon potassium bitartrate crystal growth. The wine additive carboxymethylcellulose, in particular, is discussed in detail, as this additive is being trialled increasingly by winemakers since its approval for winemaking.