This spot test may be performed by wetting the thallus with K followed immediately by C. The initial application of K breaks down (via hydrolysis) ester bonds in depsides and depsidones. If a phenolic hydroxyl group is released that is meta to another hydroxyl, then a red to orange colour is produced as C is applied. Alectoronic acid and physodic acid produce this colour, while a violet colour results when picrolichenic acid is present. The CK test is a less commonly used variation that reverses the order of the application of chemicals. It is used in special cases when testing for orange colour produced by barbatic acid or diffractaic acid, such as is present in Cladonia floerkeana. Lugol's iodine is another reagent that may be useful in identifying certain species.
Hypogymnia tubulosa is a lichen that is KC+ (orange-pink) because of the depsidone physodic acid; Cetrelia olivetorum is KC+ (pink-red) due to the depsidone alectoronic acid.