Liqui-Nox is a detergent-based latent print reagent specifically formulated to develop latent fingerprints on adhesive surfaces, such as tapes. Its primary advantage lies in its ability to visualize latent prints without the background staining often associated with other adhesive tape processing methods.
Equipment
- Camel Hair Brush: A soft, natural hair brush used for gently applying the reagent.
- Shallow Tray or Dish: To hold the Liqui-Nox solution.
- Running Water Source: For rinsing treated surfaces.
- Protective Gloves: Nitrile or similar to protect your skin.
- Safety Glasses: Eye protection is essential when working with chemicals.
Ingredients and Quantities for a 1-Liter Solution of Liqui-Nox
- Liqui-Nox Detergent: 10 ml (approximately 2 teaspoons)
- Distilled Water: 1 Liter
- Black Fingerprint Powder: A small amount (approximately 1-2 grams)
Mixing Procedure
- Combine Ingredients: In a clean container, add the Liqui-Nox detergent to the distilled water. Stir gently until the detergent is completely dissolved. Avoid creating excessive foam.
- Add Fingerprint Powder: Sprinkle a small amount of black fingerprint powder into the mixture. Stir until the powder is evenly distributed.
- Adjust Consistency: The ideal consistency is that of a slightly foamy shaving cream. If needed, add tiny amounts of water or detergent to achieve this.
Latent Print Processing using Liqui-Nox
- Reagent Application: Using the camel hair brush, gently apply the Liqui-Nox mixture to the adhesive side of the tape, working in a consistent direction. Create a light foam.
- Wait Time: Allow the reagent to sit for 30-60 seconds.
- Rinse: Rinse the tape under a gentle stream of cool tap water to remove the reagent.
- Air Dry: Allow the tape to air dry completely.
- Examination: Examine the dried tape under normal lighting. Developed latent prints will appear as dark ridges against the tape background.
Storage Requirements
- Airtight Container: Store the unused Liqui-Nox detergent in its original airtight container.
- Cool, Dry Location: Store the detergent away from direct sunlight and heat sources.
Shelf Life
- Detergent: The Liqui-Nox detergent, when stored properly, has a long shelf life (check the expiration date on the container).
- Mixed Solution: It's best practice to make a fresh Liqui-Nox solution for each use. Mixed solutions are prone to degradation over time.
Important Notes:
- Liqui-Nox is considered a relatively safe reagent, but it's always good practice to wear gloves and eye protection when working with any chemicals.
- Experimentation is key. The amount of fingerprint powder added can be adjusted to influence contrast.
- Liqui-Nox is designed for standard tapes. It may yield less optimal results on specialized or heavily textured tapes.