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Soap Making Overview
Soap
is the result of a chemical reaction between a base called lye (NAOH)
and any variety of oils (fat). This chemical reaction is called
“saponification”. Handmade soap differs from industrial soap
in that, usually, an excess of fat is used to consume the alkali
lye (super fatting) and in that the
glycerin is not removed,
leaving a naturally ultra moisturizing soap.
Super
fatted soap is more skin-friendly than industrial soap, although
if too much fat is added it can leave users with a "greasy" feel.
Often,
emollients such as
jojoba oil or
shea butter are added 'at
trace' (when the soap has begun to thicken), after most of the base
oils have saponified, so that they remain unreacted in the finished
soap. Super fatting can also be accomplished through a process called
superfat discounting, where, instead of putting in extra fats, the
soap maker puts in less lye. The most popular soapmaking process
today is the cold process method, where fats such as
olive oil react with
lye. Some
soapers still use the historical
hot process.
Lye and Oils
Soap is derived from
either vegetable or animal fats. Reacting fat with sodium
hydroxide (NaOH) will produce a stable soap that will usually become
firmer as it cures.
An array of oils and
butters are used in the process such as olive, coconut, palm, cocoa
butter,
hemp oil and shea butter to provide different qualities. For
example, olive oil provides mildness in soap; coconut oil provides
lots of lather; while coconut and palm oils provide hardness. Sometimes
castor oil can also be used as an ebullient. (All CherryLand
Soap is made from high quality vegetable oils, such as
palm, olive and coconut oil). If soap is made from pure
olive oil (or a high percent of Olive Oil) it may be called
Castile or
Marseille soap. Since properties of oils affect the quality
of the soap, many soapers keep their recipes proprietary.
Process
Cold-process soapmaking
requires exact measurement of lye and fat and precise computation
of their ratio, using saponification charts to ensure that the finished
product is mild and skin-friendly. Saponification charts are not
as necessary in hot-process soapmaking. Cold-process soapmaking
takes place at a sufficient temperature to ensure the
liquification
of the fat being used. The lye and fat are kept warm after mixing
to ensure that the soap is completely saponified.
Unlike cold-processed
soap, hot-processed soap can be used right away because lye and
fat saponify more quickly at the higher temperatures. Hot-process
soapmaking was used when the purity of lye was unreliable.
This process can use natural lye solutions, such as potash. The
main benefit of hot processing is that the exact concentration of
the lye solution does not need to be known to perform the process
with adequate success.
Cold process (CherryLand Soaps uses
the Cold Process)
A cold-process soapmaker
first identifies the saponification value of the fats being used
which is then used to calculate the appropriate amount of lye needed.
Excess unreacted lye in the soap results in a high pH and can burn
or irritate skin. Not enough lye and the soap is greasy. Most soap
makers formulate their recipes with a 4-10% discount of lye so that
all of the lye is reacted and that excess fat is left for skin conditioning
benefits.
The lye is dissolved
in distilled water. Then oils are heated, or melted if they are
solid at room temperature. Once both substances arrive at approximately
100-110°F (37-43°C), and are no more than 10°F (~5.5°C) apart, they
are combined. This lye-fat mixture is stirred until "trace" (modern-day
soapmakers often use a stick blender to speed this process). "Trace"
corresponds roughly to viscosity. There are varying levels
of trace. Depending on how additives will affect trace, they may
be added at light, medium or heavy trace. After much stirring, the
mixture becomes the consistency of thin pudding.
Essential oils,
fragrance oils, botanicals, herbs, oatmeal or other additives
are added at light trace, just as the mixture starts to thicken.
The batch is then poured
into molds, kept warm with towels, or blankets, and left to complete
saponification for 18 to 48 hours. Milk soaps are the exception.
They do not require insulation. Insulation may cause the milk to
burn. During this time, it is normal for the soap to go through
a "gel phase" where the opaque soap will turn somewhat transparent
for several hours, before once again turning opaque. The soap will
continue to give off heat for many hours after trace.
After the insulation
period the soap is firm enough to be removed from the mold and cut
into bars. At this time, it is safe to use the soap since saponification
is complete. However, cold-process soaps are typically cured and
hardened on a drying rack for 2-6 weeks (depending on initial water
content) before use. If using caustic soda it is recommended that
the soap is left to cure for at least four weeks.
Hot process
In the hot-process method,
lye and fat are boiled together at 80–100 °C until saponification
occurs, which the soapmaker can determine by taste (the bright,
distinctive taste of lye disappears once all the lye is saponified)
or by eye (the experienced eye can tell when gel stage and full
saponification have occurred). After saponification has occurred,
the soap is sometimes
precipitated from the solution by adding salt, and the excess
liquid drained off. The hot, soft soap is then spooned into
a mold.
References
-
Wickepedia
-
Willcox, Michael
(2000). "Soap". in Hilda Butler. Poucher's Perfumes, Cosmetics
and Soaps (10th edition ed.). Dordrecht: Kluwer Academic Publishers.
pp. 453. "The earliest recorded evidence of the production of
soap-like materials dates back to around 2800 BCE in Ancient
Babylon."
-
Pliny the
Elder,
Natural History,
XXVIII.191.
-
Butler, p. 454.
-
a
b
Partington, James Riddick; Bert S Hall (1999). A History of
Greek Fire and Gun Powder. JHU Press. pp. 307.
ISBN 0801859549.
-
footnote 48,
p. 104, Understanding the Middle Ages: the transformation of
ideas and attitudes in the Medieval world, Harald Kleinschmidt,
illustrated, revised, reprint edition, Boydell & Brewer, 2000,
ISBN 085115770X.
-
p. 632, chapter
11, Anionic and Related Lime Soap Dispersants, Raymond G. Bistline,
Jr., in Anionic surfactants: organic chemistry, Helmut Stache,
ed., Volume 56 of Surfactant science series, CRC Press, 1996,
ISBN 0824793943.
-
Robinson,
James Harvey (1904).
Readings in European History: Vol.
I. Ginn and co.
http://www.fordham.edu/halsall/source/carol-devillis.html.
-
McNeil, Ian
(1990).
An Encyclopaedia of the history
of technology. Taylor & Francis.
pp. 2003–205.
ISBN 9780415013062.
http://books.google.de/books?id=uxsOAAAAQAAJ&pg=PA203.
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