Lather Rinse Repeat

Lather. Rinse. Repeat.'' These are the instructions on a bottle of shampoo and are a canonical example of TooMuchDocumentation. If your product's customers don't know how to use shampoo, why are they buying it?

[Uh, oh - Assumption Warning! User Is Assumed To Be Product Domain Knowledgeable Before First Operation!]

On WikiWiki, this is most commonly used as an example of the MoreIsBetterFallacy. One washing will suffice, but why stop when you can use twice as much of the product?

Computer programmers will note that strictly following the instructions results in an InfiniteLoop.

"According to this page [], GraceHopper made that joke first"

[That depends on how you take repeat. In music, a repeat symbol instructs the musician to play the foregoing notes once more. In prose, it is shown as the word repeat. Ordinary users who get a lyric sheet have no problem understanding what the word repeat means in this context, even if they are engineers. :-} Even less trouble with instructions like repeat verse or repeat chorus. Essentially, the bare repeat means, "Take the instructions you just executed as a function definition, and execute the function."]

''except for the times the repeat doesn't mean once, like during graduation processions, where the repeated section of "Pomp & Circumstance" may get 4 or more repetitions"

Other examples of unnecessary instructions:

The computer-industry equivalent of such instructions would be If technical writers wrote the instructions for shampoo with the same standards that are usually followed for software user manuals, they'd have five pages describing how to lather, another five describing how to rinse, and a few pages of guidelines as to what conditions warrant a repetition of the process. CompUSA would offer training courses to all shampoo buyers. And there would be updates available on the shampoo web site.


See bottom for another application of this phrase.
They'd probably put instructions on toilet paper, if they could figure out an inoffensive way to describe the procedures. (But this would resolve disagreements over which is the proper direction to wipe, and whether the product should be folded or loosely crunched before use.)

They provide a phone number to call should you have questions. (Really, they do! Go look! ;-)

[There! Now this settles it once-and-for-all: The diagram on the back of Charmin shows the toilet paper coming off the TOP of the roll, not under the back. ;-> ]

I've been told that the U.S.Navy has standardized on three sheets per wipe, and that they include this somewhere in basic training.

I knew I could find instructions somewhere:
Lawn mowers always crack me up. I'll have to go find a new one and count how many warning labels are on it.

Try a barbecue powered by some kind of flammable gas. Two overlapping sets of warnings: one in the assembly manual and one in the user manual. And that doesn't count the labels on the gas cylinder itself. On the other hand, there's a very real risk that an improperly assembled, used, or stored gas barbecue could level the neighborhood. [Oops - slight overstatement...]
There's also the classic example from SoLongAndThanksForAllTheFish (page 154-155, in my copy):
"Ah yes," he said, "that's to do with the day I finally realized that the world had gone totally mad and built the Asylum to put it in, poor thing, and hoped it would get better."
Hold stick near centre of its length. Moisten pointed end in mouth. Insert in tooth space, blunt end next to gum. Use gentle in-out motion.
"It seemed to me," said Wonko the Sane, "that any civilization that had so far lost its head as to need to include a set of detailed instructions for use in a packet of toothpicks, was no longer a civilization in which I could live and stay sane."
-- GavinLambert

Just found - a similar sort of thing. -- GavinLambert
I'm surprised that no one has remarked that LatherRinseRepeat is a marketing scam. The instructions say Repeat - Thereby doubling the amount of shampoo you use (and the amount of shampoo they sell to you).

I used to think so too, but I tried it and although I didn't notice any difference in my hair, my scalp felt, well, better. I always LatherRinseRepeat now. Note that you can use the same amount of shampoo by dividing your initial shampoo amount between the two iterations. -- AndyPierce

[I have tried not repeating the procedure. The results are not nearly as satisfying (hair not as clean) as using two full cycles. This has been the same regardless of shampoo brand. Does it occur to you that the folks who dedicate their lives to making shampoo might know a little something you don't?]

I now apply two cycles of washing to my hair too. I use much less shampoo for each. The first gets most of the oil out, and the second lathers up really easily with very little shampoo. My theory is that much of the oil is removed in the first cycle is not directly joined with the soap, so adding more shampoo to the first cycle wouldn't get much more oil out, rather it would simply waste the soap by sticking it to the unjoined oil. Regardless of why, it works for me. -- Anon

Your experiments are confirming the comments I made earlier in the page about dynamic equilibrium. It's not a scam.

Although that usually is a scam, it is not always so. We've had inkjet printers shipped back to us which were used with aftermarket cartridges that leaked and destroyed the printer. (Note that I work where we make the original cartridges.)
One thing that professional hairstylists keep telling me, which never seems to appear on any shampoo bottle label: don't use the same shampoo all the time. Sometimes, the advice is to alternate between shampoo brands weekly, or daily, or between the first and second latherings (ExtremeShampooing). This supposedly cleans out stuff that would otherwise build up (not everything in a shampoo bottle is intended to clean your hair). -- ZygoBlaxell
While I won't pretend to know the purpose for the LatherRinseRepeat documentation, I will say this: It might be conceivably useful for someone facing a major cultural shock, who has never used shampoo before. I don't know the hair-cleaning habits of all the cultures around the world, but I don't think it's too hard to imagine a culture where hair-cleaning is not accomplished with a thick fluid that can lather up like soap.

I'm reminded of the fact that the last time I visited Korea, I saw they had pictorial documentation on the cereal boxes. Summarized with words, the instructions were essentially.

Pour in a bowl. Add milk. Eat.

Which is fairly comical, unless you've never seen a bowl of cereal before in your life - at which point it's genuinely helpful.
I bought a digital camera once that included, at the front of the manual, "Do not use this camera if it is emitting smoke or is on fire". I'm not sure which scared me: that there was enough of a risk of it catching fire to need to mention this, or the fact someone, somewhere needed this pointing out to them... -- KatieLucas
I think that you're likely to hit some kind of runtime exception instead of an infinite loop. Eventually, you'll run out of shampoo (and be unable to execute Lather), or water (and be unable to execute Rinse) or hair (which removes the need to use shampoo in the first place).
My favorite warnings were on the back of a mid-80s rack-mounted Emu synthesizer. The first one warned against letting the unit become too hot; the accompanying pictogram showed an egg frying on the unit, with a superimposed "no" circle-and-slash. The second warning was "do not drop penguin onto unit from airplane"; the pictogram was a penguin landing head-down on the unit after falling from an passing airplane, again with the circle-and-slash. To this day I wonder how many people saw them.
Am I the only here guy old enough to remember Chris Elliot's "Conspiracy Guy" character on David Letterman? He believed the Shampoo Industry was behind this LatherRinseRepeat meme in order to sell more shampoo. -- RogerKnobbe
Actual warning seen posted officially recently in a public washroom: "Please do not stand on the seats. Sitting is much more comfortable" Sometimes though most people should be able to use a product without documentation, constraints have to be specified to avoid misuse. Though for this case I admit I don't know if there had been a history which prompted this warning.

In many parts of the world (parts of Asia for sure, probably other places as well), sit-down toilets are unknown, or only for the rich. Everyone else squats over various sorts of holes in outhouses, or squats over what amounts to a narrow toilet bowl set into the floor. It is generally called a squat pot in English. It is rather practical, considering how gross it is to sit on a toilet seat where strangers sit, and all the workarounds that we Westerners have had to invent to avoid sitting on the same seat ("for your protection," etc.). Much of the world is quite comfortable in a squatting position, as well. Predictably, people used to squatting have as much difficulty understanding the sitting paradigm as most people who are used to sitting have with the squatting paradigm. Places frequented by refugees, immigrants, etc. therefore have a predictable problem related to getting people NOT to squat on the toilet seat.

I was born and live in the US and somehow learned to squat on the toilet seat rather than sit. It works just fine, and the back of the toilet can be used as a handy surface to read books from. -- Anon

[Note, however, the public-toilet-seat scare is merely an urban legend, a myth. Germs like warm, moist environments. A toilet seat is neither. Furthermore, most people's faces are dirtier than their seats. It's perfectly safe and clean "to sit on a toilet seat where strangers sit." And a discussion of the workarounds so many of us go through to avoid doing so I'm sure belongs on a page somewhere on this Wiki.] Not necessarily true. It depends on how quickly the toilet seat is reused, the particular virus(s)/bacteria(s) involved, and whether the second person has a spot of compromised skin (i.e. scratch; open wound; open pimple; etc.) My kid is in med. school. But this overlooks that, in the men's loo at least, seats are often gross precisely because warm and moist. -- BrianvandenBroek?
You people have thought about this too much :-)
My favourite docs are those included with cheap electronics made in Asia, where it is obvious that the writer doesn't quite grok English. In the early 1980's my younger brother got an el-cheapo RadioShack electronic keyboard. The instructions that stuck well enough that I am sure of the quotes: On the other hand, many examples on this page are of putatively useless documentation, all too sadly, not genuinely useless. While one would think that anyone who had things together enough to pick up a camera would probably also be able to work out not to continue use when it's on fire, one would also think that anyone able to operate a motor vehicle would probably be able to work out that holding hot coffee in your crotch isn't the best idea either. Turns out American courts don't agree. -- BrianvandenBroek?

Oh, stop repeating that moronic misunderstanding of the lawsuit. It makes you look like a complete fool. Read the facts here: Yes, Virginia, sometimes big corporations do make mistakes that hurt REAL PEOPLE.
I'm sure there's a useful, unambiguous way to say "LatherAndRinseTwice?" but there would likely be frowns if the bottle read "Lather and rinse once to remove surface grime, lather and rinse again to remove deeper scalp oils" or something like that. We could go for the (litigation sensitive) approach: "Lather, rinse, repeat. Stop when desired amount of dirt and oil has been removed from hair. WARNING: Too many repetitions may result in [insert bad things here]."

And then there's the BlondeJoke? about the blonde gal who shows up at the store and bought a new bottle shampoo every day: when asked why, she recounts the instructions on the label ... "and then it says repeat, so I do ..." which uses up the entire bottle.

-- GarryHamilton
Oh, and there's another application for LatherRinseRepeat. It's used in describing specific tasks or even the duties of an occupation.

So, Susan, what do you do? Well, I pick up the mail, open it, attach the envelope, determine who should get it and either put it in his basket or deliver it to him. Lather, rinse, repeat.
	What am I supposed to do with the cards in this box?
	Oh, those need sorting.
	Just look at the ID in the upper right corner
	then find the drawer with that code group
	and locate the ID before it and after it
	and insert the card between those two.
	Lather, rinse, repeat.
Yes, people actually say things like that. -- GarryHamilton

why? repeat is too succinct? -- JamesKeogh
When I was skydiving my parachute had a standard warning on it from the manufacturer effectively absolving them of all responsibilities and recommending that it wasn't used.
Has anyone ever achieved the maximum number of people certified to be in an elevator?

I wonder if there is a maximum number of certified people allowed in an elevator. And if so, how many of the people who've posted to this page qualify.
This page starts out as being wonderfully funny and pedantic; the LatherRinseRepeat cycle, brought back nightmares of writing PascalLanguage code; then continued on to become nightmarish in showing the ridiculousness of litigious idiocy by people who ought not be allowed to do anything parental. :) If I recall correctly, it began with the plastic wrappers and the "new warning", describing that the plastic is not a toy. Wow, its memory makes me cringe. -- IdKnow
Contrast: TeachMeToSmoke


EditText of this page (last edited February 13, 2011) or FindPage with title or text search