Gentian Violet / Crystal Violet

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Chemical Name:
Gentian Violet / Crystal Violet
Surface Used On:
Glutinous or sticky/adhesive surfaces, especially tapes.
Sensitive To:
Epithelial skin cells, Sebaceous lipids & Proteins.
Development Color: Method to Record: Hazard: Protective Clothing: Fume Hood Use:


Reagent Characteristics

Development Complete When:

Source of Error:



Storage Container:



Similar Reagents

Sequential Reagents
(Not necessarily in this order.)

Abridged Reagent Sequence

Visual Examination
Forensic Light
*** Gentian Violet ***
Forensic Light

Gentian Violet / Crystal Violet FORMULA:
   1 ml Gentian Violet solution
1000 ml distilled water.
   1 g Gentian Violet crystals 
1000 ml distilled water.
1. Gently agitate the item in a tray
containing the reagent solution
for 1 to 2 minutes.
2. Running cold tap water rinse - 30 seconds.

3.  Allow to air dry.
4. View visually, or with a 
forensic light source between 
505 nm - 570 nm with red goggles. 
 10 ml Hydrochloric acid in 
 90 ml of tap water. (10% soln.)

Ridge Detail Visualized by:

Visible chemical/stain reaction.
Forensic Light Source induced.

Reagent Applicabilities:

Tape surfaces
Non-Porous surfaces
Fluorescent technique

Other Chemical Name(s):

Crystal violet
Crystal violet chloride
Aniline violet
Basic violet 3
Bismuth violet.

Working Solution Shelf-life:


Process Summary:

This is a dye staining process using a water-based working solution. The reagentis a fat-soluble dye stain. The treated evidence is repeatedly stained and rinsed until optimum development occurs. This reagent may be applied to surfaces that are contaminated with oils and grease.

Accepted Deviations:

The working solution may be re-used. The working solution may also be applied by brushing. The developed detail may be viewed under a forensic light source at 505 nm to 570 nm using red viewing goggles.

This dye stain may be used for post-cyanoacrylate enhancement.

Supporting Reference Materials:

1. "A Modified Crystal Violet Application Technique for Black Electrical Tape", Jor. Forensic Identification, Vol. 40, No. 3, May/June 1990, pp. 148-150.

2. "Chemical Formulas and Processing Guide for Developing Latent Prints", U.S. Dept. of Justice, pg. 47-48, 1994.

3. Advances in Fingeprint Technology 2nd. Ed., Lee, H.C. & Gaensslen, R.E., CRC Press, Boca Raton, FL., 2001, pp. 121-122.

4. Manual of Fingerprint Development Techniques: A Guide to the Selection and Use of Processes for the Development of Latent Fingerprints, 2nd. Ed., Ed. Kent, T., Police Scientific Development Branch, Sandridge, St Albans, Hertfordshire AL4 9HQ. UK., 2001.

5. Fingerprints and Other Ridge Skin Impressions, Champod, C., Lennard, C.; Margot, P.; Stoilovic, M., CRC Press: Boca Raton, FL, 2004, pp. 160-161.

6. "Sticky-side Powder Versus Gentian Violet: The Search for the Superior Method for Processing the Sticky-side of Adhesive Tape", Gray, M. L., Jor. Forensic Identification, vol. 46, no. 3, May/June 1996, pp.268-273.

7. "Development of Latent Prints on Black Plastic Tape Using Crystal Violet Dye and Photographic Paper", Wilson, B.L. and McCloud, V.D., Identification News, March 1982, pg. 3.

8. "RAY Dye Stain Versus Gentian Violet and Alternate Powder for Development of Latent Prints on the Adhesive Side of Tape", Wilson, H.D., Jor. Forensic Identification, Vol. 60, no. 5, Sept/Oct 2010, pp.510-523.

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