The rose red dye in the mucicarmine staining solution gets its color from the aluminum-carminic acid complex carmine. This carminic acid is extracted from the dried bodies of female cochineal insects know as Coccus cacti.
While the exact chemistry of this staining technique is still unknown, researchers believe that the aluminum salts in the solution form a complex with the carminic acid. This positively charged complex then goes on to attract and bind with acid mucins in the tissue sample.
In this staining procedure, Weigert's iron hematoxylin is employed to stain nuclei black while the remaining background tissue elements are stained yellow with metanil yellow or tartrazine.