Zinc chloride

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Chemical Name:
ZINC CHLORIDE

Surface Used On:
Porous surfaces.

Sensitive To:
Ninhydrin, 5-MTN & 1,2-Indanedione compounds.

Development Color:	Method to Record:	Hazard:	Protective Clothing:	Fume Hood Use:
Orange fluorescence.	Orange or Red filter.			Yes

Reagent Characteristics

Development Complete When:

Source of Error:

Incompatibilities:

Precautions:

Storage Container:

Safety:

Recommendations:

Similar Reagents

ZINC CHLORIDE FORMULA:


  30 g Zinc chloride dissolved in
 500 ml methyl-tert-butylether (MTBE)
  20 ml of anhydrous Ethanol.

Use magnetic stirrer until completely 
dissolved. Dissolution may be slow.
Add 10 ml  Glacial acetic acid.
Dilute with 500 ml Petroleum ether.

PROCEDURE OF APPLICATION

1. Spray the item lightly.
2. Air-dry the item.
3. Process & dry a second time.
4. Oven bake at 80 - 100 
degrees C at 65% humidity 
for 20 minutes.


NINHYDRIN & 5-MTN TREATED ITEMS:

View under a forensic light 
source 450 nm to 530 nm.  
Use dark orange or red barrier filters.


Photograph results using a 
orange colored or 
550(BP 35) bandpass filter.



1,2-INDANEDIONE TREATED ITEMS:

For most papers ......

View @ 515 nm with orange barrier
filter.

For manila, brown paper bags,
cardboard items & craft paper ....

View @ 515 - 570 nm with
orange or red 600(BP 35)
barrier filters.

Ridge Detail Visualized by:

Forensic Light Source induced.

Reagent Applicabilities:

Porous sufaces
Fluorescent technique
Post-Ninhydrin

Other Chemical Name(s):

None

Working Solution Shelf-life:

Six (6) months.

Process Summary:
Zinc chloride is applied as post-ninhydrin , post 1,2-Indandione & post 5-MTN treatments in order to improve the strength of the fluoresence of the ridge detail for viewing and photography. When viewing the enhanced ridge detail, two approaches may be utilized ... 1). the Zinc chloride color-shifted ridge detail may be darkened with the appropriate wavelength and viewed without any barrier color filter, or, 2). the appropriate wavelength may illumine the latent print, which is viewed with the appropriate barrier color filter.

Zinc chloride treated ninhydrin ridge detail is color-shifted to an orange color, and Zinc chloride treated 5-MTN ridge detail is color-shifted to a reddish-purple color.

Accepted Deviations:
Other hydrocarbon solvents such as Pentane and Heptane may be subsitituted for Petroleum ether. The Zinc chloride treated item may also be viewed under white light using a blue or a green filter, which should darken the light pink or orange colored ridge detail.

Supporting Reference Materials:
1. "Chemical Formulas and Processing Guide for Developing Latent Prints", U.S. Dept. of Justice, pg. 47-48, 1994.
2. Manual of Fingerprint Development Techniques 2nd. Ed., Home Office - Police Scientific Development Branch, White Crescent Press, Ltd., Luton, England, 2001.
3. Advances in Fingeprint Technology 2nd. Ed., Lee, H.C. & Gaensslen, R.E., CRC Press, Boca Raton, FL., 2001.

[ Return to: Main Page || Porous Surfaces || Amino Acid Techniques || Eccrine Techniques || Post-ninhydrin Techniques || Fluorescent Techniques || Wood Surfaces ]