Fingerprints-latent:

Question:

Gentian Violet for fingerprinting is a banned substance now and is not procurable any more. Are there any alternatives?

Answer:

1. On wood in silver nitrate.
2. Finger prints on filter paper in iodine chamber.
Use a fume hood.
Put fingerprints on filter paper and attach a paper clip and cotton thread to it, and dangle it into a jar containing a few crystals of iodine (also hazardous). The fingerprints slowly appear. The iodine can go back into the iodine jar.
3. On smooth non-porous surfaces with Supaglue.
(a) Put fingerprints on a suitable item. CAREFULLY squirt some Supaglue into a large zip-lock bag and place the finger-printed item into the bag. Zip it up.
(b) Put microscope slide into a glass petri dish and put a dob of Supaglue onto a cover slip or second slide beside it. The effect can be speeded up by placing petri dish lid on, because the concentration of fumes is stronger, and adding boiling water to slides (not petri dishes) because Supaglue degrades at 86 degrees C.
(c) Make a small container from aluminium foil and put a small amount of Supaglue in it. Place into a takeaway container with a microscope slide with fingerprint. Put the lid on and leave it till next lesson. The vapour from the Supaglue highlights the print.
(d) Put aluminium can which has been finger printed into a zip-lock bag. Add a warm wet cotton wool ball. WITH CARE, add generous amount of Supaglue. Blow moist hot air into bag and seal it. Float bag in large beaker of warm water.
Vapours from Supaglue attach to finger prints and crystallize out

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