If there's one household appliance most
of us simply could not do
without, it's the clothes washer. If you've ever been without your
machine for a few days or weeks, you'll know just how hard it is to
wash clothes by hand. Although clothes washers look pretty
straightforward, they pull off a really clever trick: with the help of
detergents, they separate the dirt from your clothes and then rinse it
away. But how exactly do they work?
Photo: European clothes washing machines like this are usually front-loaders: you put your clothes into that little circular window at the front. In the United States and Asia, top-loading machines are more common. Front- and top-loaders work a bit differently, as described below.
The basic idea of a clothes washer is simple: it sloshes your
clothes about in soap suds for a while and then spins fast to remove
the water afterward. But there's a bit more to it than that. Think of a
clothes washer and you probably think of a big drum that fills with
water—but there are actually two drums, one inside the other.
Photo: Inside a clothes washer drum. The
paddles turn the clothes through the water. The holes let the water in (from above)
and out (from below). The rubber seal (gasket) stops water leaking out through the door.
The inner drum is the one you can see
when you open the door or the lid. In a front-loading clothes washer, common in Europe, the
drum faces forward. You push your clothes inside
the door from the front and the whole drum rotates about a horizontal axis
(like a car wheel). The drum
has lots of small holes to let water in and out and paddles
around the edge to slosh the clothes around. In a toploader, more
common in the United States and Asia, you open a lid on top and drop
your clothes into the drum from above. The drum is mounted about a vertical
axis but doesn't actually move. Instead, there's a paddle in the middle of it called
an agitator that turns the clothes around in
the water.
Photo: Clothes washing from yesteryear. This GEC electric washing machine, dating from 1935, was much more primitive than today's machines. There was no spinning to get the clothes dry: instead, you had to use a wringer (also called a mangle) fitted to the top of the machine (a pair of rollers through which you fed the clothes to squeeze out the excess water). This one is an exhibit at Think Tank, the science museum in Birmingham, England.
There's a second, bigger drum outside the inner drum that you cannot
see. Its job is to hold the water while the inner drum (in a
front-loader) or the agitator (in a toploader) rotates. Unlike the
inner drum, the outer drum has to be completely water-tight—or you'd
have water all over the floor!
The two drums are the most important parts of a clothes washer, but
there are lots of other interesting bits too.
There's a thermostat
(thermometer mechanism) to test the temperature of the incoming water
and a heating element that warms it up to
the required
temperature. There's also an electrically
operated pump that
removes water from the drum when the wash is over. There's a mechanical
or
electronic control mechanism called a programmer,
which
makes the various parts of the clothes washer go through a series of
steps to wash, rinse, and spin your clothes. There are two pipes that
let clean hot and cold water into the machine and a third pipe that
lets the dirty water out again. All these pipes have
valves on
them (like little doors across them that open and shut when necessary).
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The washing machine program
Photo: Controlling a washing machine: Top: An old-style mechanical clothes washer programmer. The dial
on the left selects the program. The dial on the right sets the wash temperature (it's effectively a thermostat). Bottom: A modern electronic programmer. These dials are mounted on a computerized
programmer circuit. The countdown-display tells you how long in hours and minutes it will be before
your washing is clean and ready to take out (one hour and two minutes in this case, for a 30°C wash
with a very fast 1400rpm spin).
All the important parts of the clothes washer are electrically
controlled, including the inner drum, the valves, the pump, and the
heating element. The programmer is like the conductor of an orchestra,
switching these things on and off in a sensible sequence that goes
something like this:
You put your clothes in the machine and detergent either in the
machine itself or in a tray up above.
You set the program you want and switch on the power.
The programmer opens the water valves so hot and cold water enter
the machine and fill up the outer and inner drums. The water usually
enters at the top and trickles down through the detergent tray, washing
any soap there into the machine.
The programmer switches off the water valves.
The thermostat measures the temperature of the incoming water. If
it's too cold, the programmer switches on the heating element. This
works just like an electric kettle or water boiler.
When the water is hot enough, the programmer makes the inner drum
rotate back and forth, sloshing the clothes through the soapy water.
The detergent pulls the dirt from your clothes and
traps it in the water.
The programmer opens a valve so the water drains from both drums.
Then it switches on the pump to help empty the water away.
The programmer opens the water valves again so clean water enters
the drums.
The programmer makes the inner drum rotate back and forth so the clean
water rinses the clothes. It empties both drums and repeats this process
several times to get rid of all the soap.
When the clothes are rinsed, the programmer makes the inner drum rotate
at really high speed—around 80 mph (130 km/h). The clothes are flung
against the outside edge of the inner drum, but the water they contain is small enough to pass through the
drum's tiny holes into the outer drum. Spinning gets your clothes dry using the same idea
as a centrifuge.
The pump removes any remaining water from the outer drum and the wash cycle comes to
an end.
You take your clothes out and marvel at how clean they are!
Artwork: Cooling down: In the United States, it's common to wash clothes at fairly low temperatures. In Europe, warmer washing is much more the norm. This chart shows the broad trend in Germany over the last few decades, where 40°C is the typical average wash temperature. New European energy-efficiency regulations and better detergents will increasingly favor lower temperatures (20°C) in the future. [Compiled from a variety of market research sources.]
Why do washing machines need so many programs?
Your machine doesn't know what you put into it and can't automatically tell how carefully to wash
something like a delicate woollen jumper—because it
doesn't know that's what it's got to do! The only things under its
control are the amount and temperature of the water, the speed of the spin, the
number of times the drum oscillates, the number of rinses, and so on.
No-one wants to wash clothes in a scientific way: "I think I need 5.42 litres of water
at exactly 42°C, I'll need to wash for exactly 34 minutes,
and I'll need 200 spin revolutions when I'm done."
That would give us literally an infinite number of possibilities, which is too much like hard work.
Recognizing this, machine engineers try to make life easy by offering a few preset programs:
each one uses a slightly different combination of these variables
so it washes safely within the tolerance of different fabrics.
Why does that matter? All fabrics are different. A fabric like wool is immensely strong but has two big drawbacks (from
the point of getting it clean): it's extremely hygroscopic (absorbs huge
amounts of water) and loses its elasticity as the temperature increases.
So if you're designing a washing machine to wash woollens, that's your starting point: don't allow the wool to
become too hot (because the fibers will degrade and stretch too much)
and don't agitate it excessively because it will stretch and not return
to shape.
With sturdier fabrics like denim, you can afford to bash them about in
the drum much more—indeed, you must do so, because you need the
agitation to get the detergent deep into the fibers and break up the dirt
(and, of course, clothes made from denim are more likely to get dirtier
than more delicate fabrics such as cashmere jumpers, which people treat
more carefully).
Each program you find marked on a clothes washing machine is a best guess by the engineers as to how
much agitation a particular garment/fabric is likely to need and how
much it can put up with without getting damaged. If you were handwashing
in a sink, you'd make those judgements instinctively, balancing the need
to get your garment clean with the need to protect it from damage. While
your brain/hands would do that without thinking, the washing machine
does it with a certain wash temperature, so many agitations, so many
spins, and a certain spin speed.
Artwork: Clothes washing machines haven't always used rotating drums powered by electricity. This one, from the 1880s, is entirely mechanical and uses a large, stationary tank (light blue) with holes perforated in its base. Underneath the tank, there's a water pump (dark blue) with a piston (red) inside. As you move the handle (brown) from side to side, the pumping piston slides back and forth, alternately shooting water up into one side of the clothes container and pulling it down through the other side (yellow arrows). According to Gifford, it was a "simple and durable construction, capable of throughly washing the clothes without subjecting them to undue friction, and wherein the action of the washer will not tend to remove any buttons." From
US Patent 409,399: Washing Machine by Hiram H. Gifford. Artwork courtesy of US Patent and Trademark Office.
But do machines really need so many programs?
Look at the programmers in the photos above and you'll see something interesting: both machines
seem to have an incredible number of programs. The mechanical programmer in the top photo offers
14 programs, seven temperatures, two spin speeds, and full or half load—and if you multiply
those you'll get 392 possibilities! The electronic programmer underneath it offers 12 programs,
5 spin speeds, and various other options so, again, a good few hundred possibilities. Yet if you're
like me, you probably wash almost all your clothes on a single program all the time. Even if you don't
do that, it's unlikely you could think of 392 different types of clothing that need washing in 392
different ways.
Much of this is a marketing con to make you believe the machine has more features than it really does.
Most machines can really do only about three or four basic washes: 1) a high-temperature, long-duration wash for
white laundry that uses a fairly high spin speed and lots of water; 2) a slightly faster, lower-temperature wash
for colored cottons that uses similar spin speed and water volume; 3) a synthetics wash that uses
the same amount of water, agitates the laundry less, spins more slowly, and uses lower temperatures; and 4) a woollens wash that
probably uses quite a bit more water, but agitates the drum less, and spins the water out relatively slowly. Any other programs are
variations of these four.
What's the difference between a front-loader and a top-loader?
The washing process is slightly different in front- and top-loading machines, so let's now look at each of these
in a bit more detail:
In a front-loading clothes washer...
There's a fixed outer drum (blue) and a rotating inner drum (red) with small holes around its edge. The drums are mounted on a horizontal axis.
The outer drum is held to the frame of the machine by heavy-duty springs. That's because, when the clothes spin, they can make the drum shake violently; the springs help to absorb the vibrations.
Hot and cold water enter through the detergent tray at the top.
The inner drum turns back and forth. The plastic paddles on the inside (shown here by gray triangles) help to slosh the clothes through the detergent and water held by the outer drum.
An electric motor turns the inner drum, typically using a long rubber belt (yellow).
When the wash cycle is finished, the pump sucks the water away.
The water empties down a tube to the drain.
In a toploader...
You lift the lid on top and drop your clothes in from above. We're looking here from one side.
Just like in a front-loading machine, there's an outer drum (blue) and an inner drum with holes in it (red), but they're mounted about a vertical axis.
Hot and cold water enter through pipes near the top, passing through the detergent tray and flushing the detergent into the machine.
During the wash cycle, a large plastic agitator (green) turns around, moving your clothes through the water. Both drums remain stationary.
The agitator is powered by an electric motor using a rubber belt.
During the spin cycle, the same electric motor turns the inner drum (red) at high speed, throwing water through its holes into the outer drum.
When the wash is finished, the pump drains the water from the
outer drum.
A very brief history of clothes washing machines
Illustration: Clothes washing remained hard work until the arrival of completely automated machines in the late 1930s. If you wanted washing doing in the late 19th century, the easiest way was to get your maid to do it for you, as shown in this advertisement for a home washing machine and wringer believed to date from around 1869. Courtesy of US Library of Congress.
It's impossible to credit any one person with the invention of the clothes washer. Like many other inventions, from cars to computers, the modern washer has evolved over hundreds of years
through the systematic mechanization and automation of hand-washing techniques people have been using since ancient times. Here are a few milestones in washing-machine history; given the hundreds (perhaps even thousands) of patents covering this sort of invention, any selection is bound to be somewhat arbitrary.
Timeline
1400s: Italian Jacopa Strada develops one of the first mechanized clothes washing machines.
1691: John Tyzacke (spelled Tizack in some sources) receives English patent 271 for a general-purpose machine ("an engine for oiling and dressing leathers and cloth") that can do many different things, including washing clothes.
1774: Hugo Oxenham invents the mangle or wringer (a pair of wooden rollers that dry clothes by squeezing water from in between them).
1782: Henry Sidgier develops one of the first rotating drum machines using a crank to power a wooden barrel, for which he gains English patent 1331.
1797: Nathaniel Briggs of New Hampshire receives one of the first US patents for a clothes washing machine.
1843: Jno Shugert of Elizabeth, Pennsylvania is granted
US Patent 3096 for a box-type washing machine in which a lever rocks the clothes back and forth through soapy water.
1858: Hamilton Smith develops a more effective rotary washing machine and is awarded US Patent 21,909.
1901: Alva Fisher of Chicago is awarded US Patent 966,677 for the first electric washing machine, sold under the brand name
Thor, which consists of an electric motor powering a more conventional drum machine. Just like a modern machine, it reverses direction periodically.
1937: John W Chamberlin, Jr and Rex Earl Bassett of Bendix develop the first automatic machine (in their words, a "washing and rinsing and drying machine operating automatically according to a definite cycle"), earning themselves US Patent 2,165,884.
1976: Servis launches Selectronic, the world's first computer-controlled clothes washer, with futuristic push-button controls.
Photo: A selection of vintage Maytag models on display at Lee Maxwell's Washing Machine Museum in Little Eaton, Colorado. Photo courtesy of Gates Frontiers Fund Colorado Collection within the Carol M. Highsmith Archive,
US Library of Congress, Prints and Photographs Division.
How to Do Laundry by Jolie Kerr. The New York Times, 21 March 2018. Simple tips for getting the most from your washer.
Device could make washing machines lighter and greener by Roger Harrabin. BBC News, 4 August 2017. Inventors have realized they can replace the heavy concrete weights in washing machines with huge water bottles, drmatically reducing weight and slashing carbon dioxide emissions.
Cold-Water Detergents Get a Cold Shoulder by Andrew Martin and Elisabeth Rosenthal. The New York Times, September 16, 2011. Manufacturers love low-temperature detergents, but consumers aren't convinced they get clothes clean.
Saying 'No' to Dingy by Arianne Cohen. The New York Times. October 7, 2009. Some top tips for effective washing: separate your clothes, don't overload your machine, use the right amount of the right detergent, and don't wash too often.
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