CHESAPEAKE BAY DIVISION - IAI
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Crowle's Double Stain

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Development Color:
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Method to Record:
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Hazard:
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Protective Clothing: 
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 Fume Hood Use:
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Formula
Procedure of Application
Development Complete When
Source of Error
Incompatibilities
Precautions
Storage Container
Safety
Recommendations
Similar Reagent
Sequential Reagents
Formula
Developer Solution (Mix until dissolved):
2.5 g of Crocein scarlet 7B
150 mg of Coomassie brilliant blue R
50 ml of Glacial acetic acid
30 ml of Trichloroacetic acid

Dilute above mixture into 1 Liter of distilled water. Use a stirring device until all the dye is dissolved.

Rinse Solution:
30 ml of Glacial acetic acid
970 ml of distilled water


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Procedure of Application
  1. Spray, immerse, or use a squirt bottle to apply the Developer solution to the item.
  2. Wait 30 to 90 seconds.
  3. Apply the Rinse solution.
  4. Repeat these steps if necessary to obtain maximum contrast.
  5. Photograph the final result.


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Development Complete When
Maximum contrast is obtained of the blood impression against the background.

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Source of Error
Excessively blood-stained items will obliterate detail.
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Incompatibilities
Porous surfaces that strongly absorb the dye.

Excessively blood-stained items.

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Precautions
Don't let the evidence overdevelop in the Developer solution.

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Storage Container
Dark or Clear stoppered glass or plastic bottles.

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Safety
Fume hood use is required for preparing and applying reagent. 
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Recommendations
The blood impression must be completely dry before processing with this reagent.







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Similar Reagent
  • Amido Black - Methanol Base
  • Amido Black - Water Base
  • Coomassie Blue
  • D.A.B.
  • Leucocrystal Violet

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Sequential Reagents
  • Amido Black - Methanol Base
  • Amido Black - Water Base

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Chemical Name
Crowle's Double Stain
​Surface Used On
Non-Porous Surfaces
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Sensitive To
Latent Print Residue and Blood Components
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Abridged Reagent Sequence
  1. Visual Examination
  2. Forensic Light
  3. Ultra-Violet Light
  4. Crowle's Double Stain
  5. Forensic Light​
  6. Amido Black
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Ridge Detail Visualized by:
Visible chemical/stain reaction​

​​Reagent Applicabilities:
Porous Surfaces
Non-Porous Surfaces
Blood Enhancement

Other Chemical Name(s):

None

Working Solution Shelf-life:
Indefinite

Process Summary:
A stain reagent used to enhance bloody impressions that are visible, and to develop latent prints. The technique consists of a developer solution and a rinse solution. Water is used as a final rinse. ​

Accepted Deviations:
Tap water may be substituted for distilled water in the Rinse solution if necessary. ​

Supporting Reference Materials:
  1. "Chemical Formulas and Processing Guide for Developing Latent Prints", U.S. Dept. of Justice, pg. 47-48, 1994.

Address
Chesapeake Bay Division - International Association for Identification   

P.O. Box 71804, 
Henrico, VA 23255
Email
cbdiaisec@gmail.com
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  • About Us
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