What is the "indelible" purple dye used to mark Iraqi voters?

December 16, 2005 12:29 AM

What is the "indelible" purple dye used to mark Iraqi voters?

After staining my fingers purple with methyl violet, and managing to remove it after a few minutes of heavy scrubbing, I am wondering how the purple dye used in these elections is known to be indelible, and what exactly it is made of. Thanks.

posted by scodger to science & nature (11 comments total)

Could be silver nitrate, but it's black and not purple. I had quite a stain on my hands for awhile.
posted by mr.dan at 1:46 AM on December 16, 2005

> Robert Dyck, the founder of CODE Inc., in Ottawa, is responsible for the indelible purple ink that stained the fingers of Iraqi voters in the recent election.

Like Coke and KFC chicken, the ink has a secret ingredient so that it can't be removed (after a few days, you shed the dyed skin), making it a simple and ingenious method of preventing voter fraud.
posted by dhartung at 2:03 AM on December 16, 2005

They use a similar method in India, although I've heard that some people have figured out how to remove it.

That said, I wonder about this method. It seems like being marked as a voter for several days could be hazardous to your health...
posted by delmoi at 7:14 AM on December 16, 2005

Gentian violet?

We've used to dye our skin for a frosh week ritual and its pretty hard to wash off if the solution too concentrated. We use it in the lab to stain cell colonies to for counting. Apparently its also used to treat thrush.
posted by LunaticFringe at 7:46 AM on December 16, 2005

I know someone who used gentian violet to treat thrush. It would have to last a lot longer on exposed skin than it does in the mouth -- might be the case though.
posted by SuperNova at 8:37 AM on December 16, 2005

I can vouch for the efficacy of Gentian violet. It takes days to come off. (I did the same ritual as LunaticFringe.)

(I recall the bottle warned of a carcinogenic ingredient, but the MSDS doesn't mention any).
posted by Popular Ethics at 11:51 AM on December 16, 2005

The methyl violet I mentioned in the intro is more specifically gentian violet. The ease with which I removed it (little bit of alcohol, lots of soap and water) suggests they would be unlikely to use this - unless they use a higher concentration and stick their fingers in for a while.

Guess we will never know for sure what it is.
posted by scodger at 11:54 AM on December 16, 2005

Sorry I don't have a better answer scodger. I should have mentioned that we immersed ourselves in a Gentian Violet / water solution for a good 10 minutes.
posted by Popular Ethics at 12:06 PM on December 16, 2005

When I was about 16, I shaved my head and had my friend draw all sorts of weird geometric designs on my scalp with iodine and gentian violet.

I assure you that, given the right concentration of gentian violet, it's not going to come off for several days. Also, keep in mind that it'll last longer if it's applied with a brush or swab as opposed to just dripped onto the skin--it gets worked into the skin better this way.

Also, methyl blue is a bastard to get off.
posted by Netzapper at 1:58 PM on December 16, 2005

They do the indelible ink thing in Bolivia too. You can remove most of the ink from your skin with quite a bit of scrubbing, but it's nearly impossible to remove from the area around your fingernails.
posted by luneray at 2:42 PM on December 16, 2005

The key is that the inks have a fat-soluble carrier that binds to fat below the top surface of the skin. As dhartung says, it "comes off" only when that layer of skin grows to the surface and sloughs off.

SuperNova - The reason gentian violet lasts a shorter time in the mouth is that the interior of the mouth is the fastest-growing tissue in the body that's exposed to the outside. If you bite your cheek or tongue and draw blood, it may be tender the next day, but it's gone in two days, because the tissue is growing and sloughing off so fast.

Anyone who's old enough to have used a Teletype machine and had to change the ribbon will remember how the purple ink stayed on your fingers for days.
posted by KRS at 6:14 AM on December 17, 2005