How to Make Fingerprint-Tracking Powder

Investigators use fingerprint evidence to help identify criminal suspects.

Children who have grown up watching television shows about forensics and spies naturally seek to emulate some of what they have seen, much as earlier generations that grew up with "Rawhide" and "Bonanza" enjoyed playing cowboys and Indians. Stores offer child-size police costumes, pretend handcuffs and toy spy gadgets; now you can help your budding investigators make their own fingerprint powder as well. Using basic household items or a specialty product or two, children can practice their fingerprinting skills, enjoy being junior investigators and maybe even learn some related science at the same time.

Things You'll Need

• Plastic table cloth or old newspapers
• 1/4 to 1/2 cup cornstarch
• Candle and matches
• 2 porcelain plates
• Table knife or small paring knife
• Tablespoon

Instructions

1. Cover your work surface with a plastic table cloth or old newspapers.

2. Place two tablespoons of the cornstarch on one of the dishes. Set aside.

3. Light the candle and hold it carefully with one hand. Hold the second porcelain dish so that the bottom is just above the lighted candle. The flame will cause black soot to form on the bottom of the plate.

4. Blow out the candle and set it aside. Use the knife to carefully scrape the black soot (graphite) off the burned plate onto the first plate next to the measured cornstarch.

5. Repeat Step 3 until there is as much graphite as there is cornstarch (about 2 Tbsp.). Carefully mix the two with a spoon until they are well-blended. Your fingerprint powder is now ready to use.

Tips & Warnings

• Add a soft shaving or makeup brush, some wide clear tape and white index cards to your powder to make a complete fingerprinting kit for your junior sleuth. Brush some powder over a print on a smooth surface and blow away excess powder. Carefully place a piece of tape, sticky side down, onto the dusted surface to lift the print. Transfer it to a white card by sticking the tape onto the card.

• In lieu of burning a plate, use a sharp knife to scrape pencil lead to obtain graphite. You can also purchase a small tube of graphite powder at hobby shops in the model car section.

• Parents should supervise their children's use of knives, open flames and graphite while making the fingerprint powder.

References

• Click Spy School; Carnegie Science Center; DIY Fingerprints
• Top Spy Secrets: Fingerprint Powder, Homemade Style
• Education.com: Make Your Own Fingerprint Powder

Resources

• Fingerprinting: Fingerprint Powder