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Fingerprint Development Techniques - Amido Black

Warning : The following procedures may require the safe handling of hazardous materials. These procedures are intended for use by trained Forensic Identification Technicians/Specialists following proper forensic laboratory health and safety protocols.

Application : Blood-contaminated latent fingerprints. Amido Black stains the protein in blood a blue/ black color. A water-based formula is shown for substrates that are affected by methyl alcohol.

Formula :
Methyl Alcohol Working solution

  • 2.0 grams amido black 10B
  • 100 mL glacial acetic acid
  • 900 mL methyl alcohol
  1. Place 2 grams of amido black into a clean, dry 2 L glass beaker.
  2. Measure out 100 mL glacial acetic acid and add to amido black.
  3. Measure out 900 mL of methyl alcohol and add to amido black solution.
  4. Stir for 30 minutes to produce a blue-black working solution.
  5. Store in a clean, dry, brown-glass bottle. Seal and label.

De-staining solution

  • 100 mL glacial acetic acid
  • 900 mL methyl alcohol
  1. Measure out 100 mL of glacial acetic acid. Pour into a clean, dry 2 L glass beaker.
  2. Measure out 900 mL of methyl alcohol and add to the glacial acetic acid.
  3. Stir until solution is clear.
  4. Store the de-staining solution in a clean, dry brown-glass bottle. Seal and label.

Water-Based Working Solution

  • 2.0 grams amido black 10B
  • 20.0 grams citric acid
  • 1 L distilled water
  1. Place 2 grams of amido black into a clean, dry 2 L glass beaker.
  2. Weigh out 20.0 grams citric acid and add to amido black.
  3. Measure out 1 L of distilled water and add to amido black mixture.
  4. Stir for 30 minutes to produce a blue-black working solution.
  5. Store in a clean, dry, brown-glass bottle. Seal and label.

Fixing Solution

  • 20.0 grams 5-sulphosalicylic acid
  • 1 L distilled water
  1. Place 20.0 grams of 5-sulphosalicylic acid in clean, dry 2 L glass beaker.
  2. Measure out 1 L distilled water and add to sulphosalicylic acid.
  3. Stir until solution is clear.
  4. Store in a clean, dry glass bottle. Seal and Label.

Development :

Methyl Alcohol-Based Working Solution

  1. Immerse exhibit in methyl alcohol pre-wash for 5 minutes to fix blood.
  2. Immerse exhibit in working solution for 3 minutes.
  3. Immerse exhibit in the de-staining solution for a few minutes until excess dye has been removed.
  4. Repeat de-staining step in clean solution if necessary.
  5. Allow to air dry before examination.

Water-Based Working Solution

  1. Immerse exhibit in 5-sulphosalicylic fixing solution for 5 minutes.
  2. Immerse exhibit in working solution for 3 minutes.
  3. Immerse the exhibit in the distilled water for a few minutes until excess dye has been removed.
  4. Repeat de-staining step in clean water if necessary.
  5. Allow to air dry before examination.

Equipment :

  • glass measuring cylinders; 100 mL, 1 L
  • glass beaker 2 L
  • brown-glass bottle 2 L (x2)
  • Magnetic stirrer plate and stirrer bars

Chemicals :

  • Acetic Acid, Glacial: A490-212 (Fischer Scientific); B27013-78 (VWR Canlab).
  • Amido Black 10B: BP124-10 (Fischer Scientific); MO1167-30 (VWR Canlab).
  • Methyl Alcohol: A412-4 (Fischer Scientific); ACS531-82 (VWR Canlab).
  • 5-Sulphosalicylic Acid: S740-8 (Aldrich); B30314-34 (VWR Canlab); A297-500 (Fischer).

Supplier :

  • Aldrich, tel: 1-800-565-1400
  • Forensi-Tech Ltd., tel: 1-613-737-5200
  • Fischer Scientific., tel: 1-800-234-7437
  • VWR Canlab., tel: 1-800-932-5000

Bibliography :

Sensitivity Comparison of Blood Enhancement Techniques , Olsen, R. D.,

Identification News , August 1985, 10-15.

Enhancement of Fingerprints in Blood - Part 1: The Optimization of Amido Black , Sears, V. G., Prizeman, T. M., J. Forensic Identification, 50(5), 2000, 470-480.

Manual of Fingerprint Development Techniques: A Guide to the Selection and Use of Processes for the Development of Latent Fingerprints , Second Edition, Ed. Kent, T., Police Scientific Development Branch, Sandridge, St Albans, Hertfordshire AL4 9HQ. UK.

Prepared by: Della Wilkinson Updated October 2001