fingerprinting

Fingerprinting; this is severely overdue but oh well.

Superglue Fuming Method

From top to bottom: Michelle, Cheryl, Yuexin, Mine.

Iodine Fuming Method

Set-up.

Mine, I think.

Power Dusting Method

Michelle's/YX's

Scraping the graphite from the pencil

Fingerprint Database

Bit blur but we all look happy :)

The pattern on my right thumb => Whorl

White Glue...Peeling Method?!

All photographs courtesy of Cheryl

Not that surprisingly, the fingerprints on my right thumb are not mirror image of my left thumb. :) (i.e. no symmetrical relationship).

SUPERGLUE FUMING METHOD

If the contrast of the white print against the black background is still too faint for a good detailed photograph to be captured, what could be done to enhance the fingerprint?

I think the dusting method, whereby coloured powder is applied and dusted off, may work since the coloured dust would attach itself to the white print so the print is more visible.

IODINE FUMING METHOD

What are the possible substances that may be used to render the prints more permanent?
Why does the print disappear?

1. iodine enhancer/fixative

2. The print is formed as a physical reaction between the iodine gas and the fats and oils on the latent fingerprint. (the fats absorb the iodine gas) We can tell it's a physical reaction from the fact the print merely changes colour; it's chemical composition doesn't change. Physical reactions are reversible; the iodine gas will sublime again. Hence the print disappears.

POWDER DUSTING METHOD

What is magnetic powder dusting and how does it work?

It's like how you would attract paper clips out of water in a tall plastic container without getting anything wet. You have a magnet on one side of the plastic sheet and magnetic iron filings or anything else magnetic on the the other side. so you drag the magnet back and forth the plastic sheet such that the magnetic stuff will stick to the fingerprint.

FINGERPRINT CLASSIFICATION

(taken from rambio2011.wikispaces.com)

Different classes have different numbers of students. Hence you cannot compare how rare or common a certain type of fingerprint is based on something like "there are more pupils in 201 with loop then the pupils in 213 who have loop. hence loops are more common in 201 than 213". It may simply be because 201 has more people in the class; so even if they have fewer percentage of people with loop, the number is still larger. That's the difference between the two graphs reflecting percentage and number.

According to the fingerprint database in the US:

• 60-65% are classified as loops
• 30 – 35% are classified as whorls
• 5% are classified as arches

Based on the 5 classes' data (and assuming that they can represent Singapore), the ranking in terms of most common and least common are the same but I think there is a higher percentage of arches in Singapore than in US, and a fittingly lower percentage of loops and whorls in Singapore.