A composition having various color changing tannates may be used to indicate that the composition has dried. The tannates change color in contact with an acid. The composition may be, for example, a skin prep, skin sealant, food product, paint or other building material or other product that undergoes a phase change. The tannate may be added either directly to the composition, incorporated into a sponge on an applicator through which the composition is dispensed and applied, applied separately or applied simultaneously from a separate reservoir. The amount of tannate in the composition can be adjusted to provide a visual cue to the user of the application area and the extent of cure.