I don’t wash my car twice in a row. I don’t wash my clothes twice in a row. So, aside from using up shampoo twice as fast, is there any benefit to “wash, rinse repeat?”
With God as my witness, I thought turkey’s could fly.
You use more shampoo.
You get stuck in an infinite loop doing that. If it weren’t for finite volume to shampoo bottles, many idiots would be showerbound for years. 
I looked in the mirror today/My eyes just didn’t seem so bright
I’ve lost a few more hairs/I think I’m going bald - Rush
Reminds me of a song:
lather rinse repeaeat
lather rinse repeaeat
lather rinse repeaeat…as needed.
I didn’t say it was a good song.
Actually the first lathering often doesn’t get my hair that clean… the second time through it really lathers up and feels a lot cleaner when I’m done.
–
Teeming Millions: http://fathom.org/teemingmillions
“Meat flaps, yellow!” - DrainBead, naked co-ed Twister chat
O p a l C a t
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I heard from the proverbial “somewhere” that the guy who came up with the idea of putting the word “repeat” at the end of the instructions on a shampoo bottle got a huge bonus. The idea is you go through the shampoo twice as fast, and have to buy more, which means twice the sales and twice the profits for the manufacturers of said shampoo.
I never could get the hang of Thursdays. - Arthur Dent
It’s unneccessary. I forgot who wrote about it, Cecil or Feldman, but its not necessary unless you feel it is…some people have a lot of hair and its beneficial for them.
I have heard this is strictly a marketing ploy. You shampoo, rinse and repeat and in the end use more shampoo.
In the world of real life, it is bad for your hair (unless your hair is extra dirty from some activity) as it strips your hair of good oils.
I, in the winter, only wash my hair every other day and only shampoo once.
This was from the inventive mind of Phoebe Buffay, Lisa Kudrow’s character on Friends.
- Rick
Phoebe would have spelled it that way, too.
It isn’t just marketing. I can definitely tell the difference between shampooing once and twice. Also, for the same total amount of shampoo, your hair will be cleaner if you wash you hair twice with half as much shampoo each time, than if you wash your hair only once with the whole amount.
It is too clear, and so it is hard to see.
ZenBeam: precisely!
The real purpose of double washing is to get the oil out. For those of you with dry hair, this isn’t a big problem, and one washing is sufficient (unless you were doing a lot of sweating).
But for those of us with oily hair, one shampooing is often not enough.
The reason why double washing is effective is that it gets more soap molecules to attach to the oil molecules. So why not just huge one huge gob of soap? Here’s the catch… you need water molecules to help the soap molecules grab the oil molecules.
Think what happens when you glob on a huge amount of shampoo onto oily hair. There’s lots of soap molecules; there’s lots of oil molecules; but the water molecules are limited – they’re rolling right off the head. So, the weak link in the process is a low amount of water.
That’s why, using a small amount of soap and washing twice is more effective than washing once with a huge gob of soap.
Now, here’s a tip for you big gobbers: After kneading in the huge gob of shampoo for a while, don’t rinse it out completely. Stick your head under the shower for a second to add more water and keep on kneading. Repeat as often as necessary until you feel the soap is practically gone. Then rinse completely. This make the most efficient use of the soap you’ve applied and will probably obviate the need to repeat.
Peace,
moriah (head and shoulders above the rest)
The bottles do say “if necessary,” if I recall correctly.
Yer pal,
Satan
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