Explorit: Dust and collect your own fingerprints at home

By From page A5 | May 24, 2013

If you’ve ever wanted to collect clues like a real detective, you can get some practice dusting for fingerprints with this science activity to try at home. You will need: colored chalk, a butter knife, cornstarch, a small paint brush, tape, paper and a variety of surfaces like a mirror, a kitchen counter, bathroom tile or a cutting board.

Start by scraping your colored chalk with the butter knife to make a fine powder. Even though butter knives aren’t very sharp, make sure an adult is there to help keep everybody safe.

Mix your powdered colored chalk with an equal portion of cornstarch. This mixture will be your fingerprint powder. Now it’s time to make some fingerprints to collect!

Fingerprints stick well on smooth, flat surfaces like mirrors or glass. The cleaner the surface, the easier it will be to collect and see your fingerprints. Test a variety of surfaces to see which ones work best. You can try a table, a plastic cup, a metal pot — the possibilities are endless!

What about a porous surface, something that has holes in it like a sponge? How well would a surface like that hold your fingerprint? Or a bumpy surface like the sidewalk outside? Do you think you could collect a fingerprint from your shirt?

When you’ve made some fingerprints and are ready to collect them, use your brush to sprinkle some of your powder on the surfaces you touched. Be careful not to touch the brush to your fingerprint; you don’t want to smear it. Just hold the brush a little above your fingerprint and shake some powder on it. You want to cover the whole print with powder.

After you’re done sprinkling, blow across the surface to remove any extra powder. Too much powder on the surface will make a messy fingerprint that will be hard to see.

Stick a piece of tape on the powder left on the surface. The oils from the skin on your finger left a pattern on the surface. The powder has now taken on the shape of that pattern and when the tape touches it, the powder will stick to the tape in the same pattern of your real fingerprint.

To best see your fingerprint, remove the tape and stick it on a piece of paper so you can see the chalk. You can experiment with different surfaces to see which ones hold your fingerprints best. Or try making a fingerprint today and dusting it tomorrow. How long do your fingerprints last on a surface?

Each person has unique fingerprints that are different from everyone else’s. But many fingerprints have designs in common like swirls or loops. You can learn more about the patterns of fingerprints at http://ridgesandfurrows.homestead.com/fingerprint_patterns.html.


Explorit’s events:

* Join us at The Klubhouse 2, 1050 Riverside Parkway, No. 125, in West Sacramento, from 6 to 8 p.m. Saturday, June 1, for a special Zumbathon to support science education. This will be a great opportunity to enjoy some high-energy cardio fitness dance fun while supporting Explorit Science Center, hands-on science activities and interactive learning.

Tickets are $20 in advance, available at http://zumbathon4explorit.bpt.me, or $25 at the door. Water will be provided, but bring a towel, because we’re going to sweat!

— Explorit Science Center is at 3141 Fifth St. For more information, call 530-756-0191 or visit www.explorit.org. You can also “like” us on Facebook at www.facebook.com/explorit.fb or follow on Twitter at @ExploritScience

Lisa Justice

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