SILVER NITRATE

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Chemical Name:
SILVER NITRATE
Surface Used On:
Porous surfaces (wood) that have not been wet.
Sensitive To:
Chlorides & salt components.
Development Color: Method to Record: Hazard: Protective Clothing: Fume Hood Use:

Brown

Not
Reagent Characteristics

Development Complete When:

Source of Error:

Incompatibilities:

Precautions:

Storage Container:

Safety:

Recommendations:


Similar Reagents



Sequential Reagents
(Not necessarily in this order.)



Abridged Reagent Sequence


Visual Examination
|
Forensic Light
|
Ninhydrin
|
*** Silver nitrate***
|
Ultra-violet light

SILVER NITRATE FORMULA:
FORMULA "A"
( 1.0 % solution )

   1 g Silver nitrate 
100 ml distilled water 


FORMULA "B"
(3.0 % solution)

 30   g Silver nitrate
1000 ml distilled water


FORMULA "C"
(Alcohol-based solution)

 30   g Silver nitrate
100  ml distilled water
1000 ml Ethanol

PROCEDURE OF APPLICATION
1.  a)  Tray immersion of item 
for 5 seconds.

    b)  Reagent solution brushed 
onto item until coated.

2. Air dry  for 20 minutes.

3. Sunlight or U.V. light 
exposure at 366 nm for ten to
sixty minutes.  Continuously 
monitor for development.



Ridge Detail Visualized by:

Visible chemical reaction.


Reagent Applicabilities:

Porous surfaces
Ultra-violet light induced


Other Chemical Name(s):

None


Working Solution Shelf-life:

Twelve (12) months.

Process Summary:
This process works by having sunlight develop the impression detail treated with the working solution. Background staining is a problem, thus the technique is not in wide use. The technique has its successes when used on wood surfaces that have not been treated with wax or varnish finishes.
Accepted Deviations:
The concentration of the reagent may be increased up to 5%. Ultraviolet light can be used instead of sunlight to develop the detail. The working solution may be applied by spraying, dipping or brushing.
Supporting Reference Materials:
1. Minutiae Magazine, Summer Special 1994, Issue No. 24, pg.7.
2. "Chemical Formulas and Processing Guide for Developing Latent Prints", U.S. Dept. of Justice, pg. 47-48, 1994.
3. Cowger, J.R. (1983), "Friction Ridge Skin", Elsevier, Page 99.
4. Olsen, R.D. (1978), "Scott's Fingerprint Mechanics", Charles C. Thomas, Pg. 291.
5. Keedwell, E., et. al. (1988), "Chemical Methods for Enhancement of Footwear Marks", Metropolitan Police Forensic Science Lab., Report No. 73, page 19.
6. Cassidy, M.J., Footwear Identification, Lightning Powder Co., Salem, Oregon, pg.59, 1995.

Return to: Main Page   ||  Porous Surfaces  ||  Eccrine Techniques  ||  Ultra-violet Induced  ||  Wood Surfaces  ]