Amido black 10B is an amino acid staining diazo dye used in biochemical research to stain for total protein on transferred membrane blots. It is also used in criminal investigations to detect blood present with latent fingerprints. It stains the proteins in blood a blue-black color. Amido Black can be either methanol or water based as it readily dissolves in both. With picric acid, in a van Gieson procedure, it can be used to stain collagen and reticulin.