[at-l] Leave your soap behind?

["David F. Addleton" <dfa@wimlaw.com>]

How many folks take soap with them on the trail? (I still carry a tiny
bottle of the stuff.) But I ran across this article at the BBC's website
which could give new meaning to the LNT ethic!

Friday, August 6, 1999 Published at 15:58 GMT 16:58 UK 


Sci/Tech

Clean and easy 

We take soap for granted 

By Pauline Newman of BBC Science 
You take the greasy animal fat from the bottom of a cooking pan. You add
the grimy wood ash from the fire below. You mix them together and use the
resulting goo to clean yourself. 
This is the essence of soap. OK, so modern soaps are a little more
sophisticated, but this is essentially how our forebears would have made
it. If you boil and cool the mixture, successively, over several days, it
will eventually go quite hard. 
Chemist John Emsley from Cambridge University says it is quite easy to
understand how soap might have been invented. 
"You can see how if someone was cooking something on a wood fire and it had
fat in it and it boiled over and the fat dropped onto the wood-ash then the
following morning, when they went to clean up the mess, they would find
that when they put water on it that it would lather and it would clean very
well. That was just a simple type of soap." 
The Pharaohs used soap nearly 3,000 years ago, and it worked for them in
exactly the same way as it works for us today. The secret of its success
lies in what are called amphiphilic molecules. 
"Soap molecules have a head and a tail," says John Emsley. "The head likes
to attach itself to water; the tail likes to attach itself to grease. So
when soap is put into water, it will find the grease, it will attach itself
to the grease, and it will pull it into the water and then it can be washed
away." 
Skin diseases 
But somehow, this miraculous property was forgotten, at least in some parts
of the world. Instead, medical men from Ancient Greece and Arab countries
used it as a skin balm, as did the Romans. 
"We know that the ancient Romans used soap because it's mentioned in
several of their books," says Nina Hall. "But they didn't use it to wash
their bodies, but instead used it as an ointment to treat skin diseases.
And in fact, a soap making factory was discovered in the ruins of Ancient
Roman Pompeii, which was destroyed by a volcano in AD 79." 
	
The Romans knew how to make soap	
The Romans did use soap to clean their clothes and they found it worked
best when mixed with urine. In the city of Florence, the Emperor urged the
townspeople to help. 
"There were great pots at the street corners where people could add their
own contributions to this," says John Emsley. "The urine was left for
several weeks until it actually decomposed and gave ammonia, and ammonia is
a very good cleaning agent. It will remove grease and dirt from fabrics." 
After the Romans, soap making, as an industry, almost ceased to exist for
hundreds of years. But there was an alternative to boiling up smelly fats
and ashes. 
"One of the simplest ways that people around the world have found to get
clean is to wash using a plant," says Pat Griggs of the Royal Botanic
Gardens at Kew, near London. "Plants are absolutely amazing for this and
there are many species around the world that contain a substance called a
saponin which works in a similar way to a soap." 
Plant power 
Over 100 different types of plants make saponin and sometimes its found in
the leaves of a plant, sometimes in the stem or roots and sometimes in the
berries or other fruits. 
"What's happening when we use one of these plants is that the saponins make
a foam when mixed with water, and this lifts off dirt and grease," says
Griggs. 
"It works just like an ordinary soap and it's often very good for washing
your hair." 
In North America, native people sometimes used the root of the Yucca plant.
In India, a shrub called the soap nut bush became very popular. The nuts
are crushed and mixed with water to make the soap. 
The bars of soap we buy today contain lots of plant material, plant oil to
make the soap itself and plant fragrance to scent it. 
We are not sure when commercial soap making began again after Roman times,
but by 1200 AD, soap was being made in Bristol in England, and 200 years
later the finest soap was being made and exported from Spain. This soap was
based on olive oil. 
Revolting mixture 
"All kinds of oils and fats can be used to make soap," says John Emsley.
"Mutton fat, tallow from cattle, palm kernel oil, coconut oil, olive oil,
palm oil - any fish oil can be used to make soap. 
"If you want the soap to last a long time then you want to use a saturated
fat. If you use an unsaturated fat then the soap will tend to go rancid
after a certain length of time. Soaps made from saturated fats will last
for years, they don't go bad." 
	
Coconut is a good source of saturated fat	
In times of hardship, when fat couldn't be spared to make soap, it has been
made out bile. Bile is a natural soap, that helps animals digest the fats
and oils they eat. During the First World War, the bile from slaughtered
animals was used as a cleaning agent. This sounds revolting because bile is
a vile green liquid but when it was processed it looked better and did a
reasonably good job. 
Today's chemists boil the fat and oil, not with wood ash, but with sodium
hydroxide, sometimes called caustic soda. 
"The general principle is to boil up fats with caustic soda," says Nina
Hall. "Water is added and they're boiled for hours and hours until we get
the soap forming. And as well as soap forming, you get glycerine and the
two have to be separated. The soap curdles, a bit like milk curdling, and
it gathers at the top of the big pans in which it's made and then the
glycerine and salts and water settle at the bottom." 
Over eight million tonnes of soap are produced each year worldwide and the
demand for soap is rising. 50 years ago, it would have all have been made
from animal and plant fats, but in recent years, more and more synthetic
soaps have been coming on the market, particularly for washing clothes. 
These are made from petrochemicals. Manufacturers like the synthetic soaps
because the raw materials, the petrochemicals, are of consistent quality.
Consumers like them because they work more efficiently and do not produce
the scum sometimes seen in hard water. 



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