Product: Soap
Soap that Stains   (+19, -3)  [vote for, against]
Not as dumb as it sounds...I hope

Getting little kids to wash their hands can be a bit of a struggle. Here then is something that will encourage them to douse those sticky puds, whilst providing parents with definitive evidence to support/disprove assertions of cleanliness by Junior.

Staining Soap combines soap with a mild, non-toxic dye that leaves the user's hands coloured for a short time after use. It comes in red, yellow, green, blue and ultra rare purple with sparkly bits.

I feel confident that if such a product had been available in my earlier years, I would have devoted many hours to repeated cleansings, simply to try and make my hands bluer than Harry next door could make his. We'd both have been told off for wasting soap, but our hands would have been scrupulously clean.
-- DocBrown, May 24 2005

Disclosure / Disclosing Tablets http://www.oralheal...osing%20Tablets.htm
[jonthegeologist, May 24 2005]

Bath Plaque Dye Bath_20Plaque_20Dye
by me. Kinda sorta related. [calum, May 24 2005]

Henna products
[2 fries shy of a happy meal, May 24 2005]

Bazooka bubble gum
No feeble practical joke stuff any more, just a boring old baseball and a mousemat. Sigh! [DrBob, May 24 2005]

US application 20020082177 http://appft1.uspto...7&RS=DN/20020082177
first soap stains hands, second soap removes stains [xaviergisz, May 25 2005]

Squid soap
Similar [tatterdemalion, Feb 09 2008]

The inventor of these bubbles sited this sort of application for the dye he developed. http://www.zubbles....y/zubblesPhotos.asp
[jhomrighaus, Feb 09 2008]

the Article from PopSci about the development of these dyes http://www.popsci.c...1/11-year-quest-cre
[jhomrighaus, Feb 09 2008]

Strangely, no... not nearly as dumb as it sounds.
-- justaguy, May 24 2005

So daft that it might actually work. Not sure how well easily you could design a dye that fades that readily. The concept's interesting, though.
-- st3f, May 24 2005

Yeah, that'd be the tough bit [st3f]. I'm hoping some specialist bakers can help out with that part, or keep quiet if it's not feasible ;)
-- DocBrown, May 24 2005

a bit like those teeth disclosure tablets, but for hands? very good [doc]
-- jonthegeologist, May 24 2005

I forsee the coloring to slowly react with some natural residue on the hands, but hand chemistry information is hard to come by... [+]
-- daseva, May 24 2005

Something using Henna maybe?
The blue is like totaly Smurfy.
-- 2 fries shy of a happy meal, May 24 2005

that self tanning cream added to the soap recipe perhaps. love the smurfy idea though. +1
-- po, May 24 2005

I've seen sunblock for kids that has purple dye in it, for similar reasons. I'm surprised nobody has done this already.
-- krelnik, May 24 2005

As I recall, you used to be able to get something similar if you saved up enough 'Bazooka Joe' wrappers. Of course the only colour dye available was black and it was for the amusement of everybody other than the user but still...
-- DrBob, May 24 2005

Could the actual bar of soap be a normal colour (white?) so that when you have guests staying over they can get it confused with the normal soap whilst having a shower and come out blue resembling either Smurfette / Papa Smurf? (+)
-- gorjabuble, May 25 2005

Or you could smell the childs hands.
-- 10clock, May 25 2005

True, but not nearly so much fun [10clock]! Besides, now I think of it, this isn't just for kids it's also for forgetful people and people like me that would just like to get their hands bluer than Harry's.
-- DocBrown, May 25 2005

Nice. "Johnny, wash up for dinner, I want to see those hands bright blue now"

As long as if faded away quickly enough I think parents would buy this. Something that makes kids want to wash their hands, what a great idea.
-- doctorremulac3, Feb 09 2008

"Among the ideas Kehoe has already mocked up are a finger paint that fades from every surface except a special paper, a hair dye that vanishes in a few hours, and disappearing-graffiti spray paint. There's a toothpaste that would turn kids' mouths a bright color until they had brushed for the requisite 30 seconds, and a soap that would do the same for hand washing."

Quote from PopSci article in links, note last line.
-- jhomrighaus, Feb 09 2008

random, halfbakery