Lather. Rinse. Repeat.'' These are the instructions on a bottle of shampoo and are a canonical example of Too Much Documentation. 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 Wiki Wiki, this is most commonly used as an example of the More Is Better Fallacy. One washing will suffice, but why stop when you can use twice as much of the product?
This is elementary physical chemistry. Shampoo (and detergents in general) interact with oils in a dynamic equilibrium. For a given amount of detergent, some oil will combine with it and some will remain free. Over any given time span some of the combined oil-detergent mix will separate, and some free oil will combine with detergent. The balance remains fairly constant unless you drive the equilibrium. You can only drive the equilibrium by removing some of the oil-detergent combination, and the best way to do this is to rinse off the existing detergent-oil combination and put in more clean detergent.
Computer programmers will note that strictly following the instructions results in an Infinite Loop.
"According to this page Grace Hopper 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:
On package of Dial soap: Use Dial as you would ordinary soap. (But what if the customer doesn't know how to use ordinary soap?)
On food: Warning: Product will be hot after removal from oven.
On fireworks: Light, then get away.
On a glass coffee pot: Fragile. Do not drop. Do not touch glass when hot. Hmm. Note that one of the most important lessons to learn when working in a chemical laboratory is that it is in general impossible to tell by looking at it how hot a piece of glassware is before you grab hold of it.
On sleeping pills: Warning: May cause drowsiness.
If bleeding or ulcers develop, consult a physician.
On chainsaw: Do not attempt to stop chain with hands.
On Heinz ketchup (humorously): Put on food
On Preparation H: Do not take orally.
The computer-industry equivalent of such instructions would be
A multimedia CD-ROM presentation that demonstrates step-by-step how to set up and turn on your new computer. (How do you view the presentation if your machine is not already hooked up?)
Instructions on how to use a mouse, how to drag-and-drop, etc., on the first few pages of every computer product manual. [Don't make assumptions about people's computer knowledge. I know many people who simply don't know how to operate a mouse. ("Helloo, Computer?")]
The computer will not be able to read the CD-ROM if it is removed from the drive. (Yes, I actually read this.)
Source code comments like "move.w d0, a0 ; move contents of register D0 into register A0" or "int getFoo() { return foo; } /* return the current value of 'foo'; preconditions: (none); postconditions: value of foo on exit is equal to value of foo on entry */"
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.
[Broken link removed]
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: [broken link removed] (Supposed to be instructions for using their web site, and "Wiping your own [...]:")
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 So Long And Thanks For All The Fish (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."
Just found a similar sort of thing.
I'm surprised that no one has remarked that Lather Rinse Repeat 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 Lather Rinse Repeat now. Note that you can use the same amount of shampoo by dividing your initial shampoo amount between the two iterations. -- Andy Pierce
[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.
A similar scam is the warning in an owner's manual to "Use only genuine XYZ replacement parts in your XYZ product". XYZ's replacement parts cost twice as much as generic parts, wear out more quickly, and can only be purchased from an authorized XYZ dealer, which doesn't exist anywhere near you, and so you have to pay an exhorbitant shipping-and-handling charge to get your replacement parts.
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.)
I've used third-party and mix-and-matched battery chargers for my various devices without ill-effect. Thing is, though, I check that the voltage and amperage ratings are appropriate first (and that the plug fits properly, of course).
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 (Extreme Shampooing). This supposedly cleans out stuff that would otherwise build up (not everything in a shampoo bottle is intended to clean your hair). -- Zygo Blaxell
While I won't pretend to know the purpose for the Lather Rinse Repeat 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... -- Katie Lucas
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 Lather Rinse Repeat meme in order to sell more shampoo. -- Roger Knobbe
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. -- Brianvanden Broek
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 Radio Shack electronic keyboard. The instructions that stuck well enough that I am sure of the quotes:
Do not strike forcefully.
Do not drop from a great height.
Do not immerse deeply underwater.
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. -- Brianvanden Broek
Oh, stop repeating that moronic misunderstanding of the lawsuit. It makes you look like a complete fool. Read the facts here: www.lectlaw.com 
Yes, Virginia, sometimes big corporations do make mistakes that hurt REAL PEOPLE.
I'm sure there's a useful, unambiguous way to say "Lather And Rinse Twice" 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 Blonde Joke 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.
Oh, and there's another application for Lather Rinse Repeat. 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. -- Garry Hamilton
why? repeat is too succinct? -- James Keogh
I dunno, James. The sense I get is one of slight "irony-of-tedium" if there is such a thing. -- gh
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.
How does one go about getting certified to be in an elevator?
This page starts out as being wonderfully funny and pedantic; the Lather Rinse Repeat cycle, brought back nightmares of writing Pascal Language 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. -- Id Know
By the way, folks if a page has broken links, why not just fix 'em and not add another tag to the page?
Contrast: Teach Me To Smoke
See original on c2.com