Amido black is used to develop latent prints and enhance visible prints that have been deposited in blood.
Caution must be exercised when applying the methanol-based formula to painted surfaces. This formula may destroy the latent print(s) as well as the surface beneath the latent print(s). All blood must be dried prior to application. Cyanoacrylate fuming may be detrimental to this process.
Equipment
Scales, beakers, graduated cylinder, magnetic stirrer and stirring bar, squirt bottles or sprayer, clear or dark storage bottles
Materials and Chemicals
Naphthol blue black
Glacial acetic acid
Methanol
Mixing Procedures
The amido black process consists of two solutions—a developer and a rinse—and a final rinse of distilled water.
Developer Solution Naphthol blue black - 2 g
Glacial acetic acid - 100 mL
Methanol - 900 mL
Combine the ingredients and mix using a stirring device until all the naphthol blue black is dissolved. This should take approximately 30 minutes.
Rinse Solution Glacial acetic acid - 100 mL
Methanol - 900 mL
Combine the ingredients.
Final Rinse Distilled water is preferred; however, if not available, tap water can be used.
Processing Procedure
Apply the developer to the specimen(s) by dipping, spraying, or using a squirt bottle. Leave the developer on the specimen for approximately 30 seconds to 1 minute, then apply the rinse. These steps can be repeated to improve contrast. Apply the final rinse of distilled or tap water, then dry the specimen(s).
Storage
Clear or dark bottle
Shelf Life
Indefinite
Disposal
Observe all federal, state, and local environmental disposal regulations. State and local disposal regulations may differ from federal disposal regulations.