First used in the 1950s by H.F. Steedman to dye mucin, Alcian Blue has become a staple in many histochemistry and cytochemistry labs. The copper present in the stain is what gives it its blue coloration. 

Alcian Blue is generally considered not to be hazardous, although reasonable caution should still be exercised. Goggles and gloves are recommended.

Staining Procedures

Carmine dye comes from crushed Dactylopius coccus or cochineal bugs. Specifically, by crushing females and their eggs, a red powder is produced, which is what makes carminic acid. Carminic acid is then boiled in water. After, aluminum salt (alum) is added, which reacts with carminic acid and is what makes the carmine dye deep scarlet red. It takes around 70,000 dried cochineal bugs to make 1kg of dye. It is suspected that carminic acid was discovered around 2000 BCE by ancient people of Mexico (specifically Puebla, Tlaxcala and Oaxaca), who harvested cochineal from the prickly pear cactus (Opuntia cochenillifera). 

Carmine is not toxic, although it has the potential to be a slight eye and skin irritant. A mask, goggles, and gloves are recommended as PPE. 

Staining Procedures

Made in 1884 by German chemist Paul Böttiger, who first synthesized the dye while working for Bayer. Bayer rejected the dye, and so Böttiger parented it and then sold it to the rival company AGFA. Ironically, the dye ended up being so popular it almost put Bayer out of business. The dye itself has nothing to do with Congo, rather the name was chosen to capitalize off of the current interest in West Africa at the time. 

Congo Red is a carcinogen, is toxic to unborn children, and is a respiratory irritant. Goggles, gloves, protective clothing, and a mask are all recommended when handling this chemical.

Staining Procedures