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What is soap?

Soap is simply made, though the chemical reaction is complex.  Chemically, an acid (the fats and oils) and a base (a
solution of sodium hydroxide and water, also called lye) react to produce soap and glycerin.  The process is called
saponification, and as the fats, oils and lye solution come into contact with one another, they react and are saponifying, or
making soap.  The mixture gradually changes from a separated mixture of watery lye and lighter fats and oils to a thicker
more uniform mixture.  The soap mixture is ready to be poured (for most recipes) when it has thickened to the point in which
a bit of the mixture is drizzled on the surface and it leaves a trail (a pattern) for a moment before disappearing.  This stage
is called a "trace" since only a trace of the pattern remains when the soap is ready.

A variety of acids, bases and several types of processes produce soap, but homemade soap is made using easily
accessible materials and a simple process called cold process.  Once the sodium hydroxide (lye) solution is added to the
fats and oils, no external heat is required as the chemical reaction produces enough heat to keep the soap making going.  
"Cold" does not mean cold; it was only called this when comparing it to the more common hot soap making temperatures
produced when heat is applied.

The two most critical chemical components of the soap making process are contact and heat.  The acid and the base must
first come together before they can react.  The heat keeps the movement and fluidity, while stirring ensures it.  Soap is
ready to pour once the ingredients have been evenly dispersed in a thick, stable emulsion.  


How does soap clean?

Soap cleans in two ways:  it helps wet the surface to be cleaned by permitting water to reach more of the surface; and it
connects the dirt to the water, permitting the dirt to rinse away.

A soap molecule consists of a chain of carbon, hydrogen and oxygen atoms that are arranged with a distinct head and tail.  
The head is attracted to water and the tail is attracted to dirt and oil.  Soap cleans because these opposing parts connect
dirt to water, permitting it to be washed away.

Soap also helps water to wt better.  Water beads up on fabric and skin because it's molecules are tightly bonded and resist
being broken apart.  The molecules cling to one another in droplets and do not soak the surface.  This is where soap
intervenes by breaking apart these droplets and help them wet the skin or fabric.  When soap molecules are combined with
water, their hydrophobic tails squeeze together in a small space, in an effort to get as far away as possible from the water
and as close as possible to one another.  The heads of the soap molecules are attracted to the water and form a spherical
wall around their fleeing tails.  The soap forms a film on the surface of the water that holds the heads and tails in position.  
The action of these heads and tails on the water's surface breaks the surface tension and forces the water into the fabric or
skin allowing the soap's lather to develop.

Once the soap molecule has helped water do it's job, it then removes dirt and grease.  The oil loving tail of the soap
molecule is attracted to oil and grease.  It first embeds it's tail into the dirt.  As the water loving head of the soap molecule
pulls toward the water, the dirt is dislodged as it remains attached to the tail of the molecule.  The tail of the soap molecule
then holds the dirt in suspension, away from the skin or fabric, until a rinse washes the dirt and the soap away.
What is soap and how does it work?