Kelly Bloom, BloomWorks Soap Co, LC Feb 2003
Most soap makers are familiar with using lye (sodium hydroxide) to make soap. We often hear the "No Lye, No Soap" refrain, but long ago soap was indeed made with NO LYE, and it was indeed soap. I have compiled here some history on early soap making, and on the origins and use of sodium hydroxide in soap manufacturing. Rember, soapmaking is really just a chemical reaction of an ACID (oil) and an ALKALI (caustic).
In the 1600's the French king issued an edict that the popular regional soap, Marseilles soap, could only bear that name if it was produced in a very specific manner. Sodium carbonate was the alkali used for saponification then, and is still used in Marius Fabre French soaps today.
If a soaper wants to make soap without lye, it is possible, but not really as practical as using lye (sodium hydroxide). It can be done, but is a much more complicated and laborious process. Saponification using other alkali's requires many more steps and ingredients to create the chemical reaction/catalyst than our method of just mixing a strong solution of lye (sodium hydroxide) & water into melted or fluid oils. Salt water rinses, long cooking periods (as many as 10 days), etc.. are not really feasible for most of us, or even warranted anymore. The method of soap making that does not use sodium hydroxide is the ancient, dying art of true soap boiling. It was one of the true soap arts guarded by the medieval soap guilds. No clear European description of how soap was made has survived from the medieval period.
Lye is not a chemical that exists by itself. Prior to 1791 Sodium hydroxide did not exist in any recognizable form. Additionally, the storage capabilities for safe handling of sodium hydroxide on a large manufacturing scale surely did not readily exist as we have today. Plastics and stainless steel were not available for storage protection of the highly reactive sodium hydroxide. But we know there was true soap being manufactured. So how was this done and what was being used as the alkali catalyst?
First some history on sodium hydroxide, also known as 'lye' and NaOH.
Sodium hydroxide is produced in the
chloralkali process, which is the electrolysis of an aqueous solution of
sodium chloride (salt). It is a by-product from the production of
chlorine. Sodium hydroxide is both hydroscopic (attracts and absorbs
water from the environment) & highly reactive, producing often violent
exothermic reactions. Until 1791 soap making alkali was commonly sodium
carbonate and soda lime, then rinsed and washed and cooked with salt water
baths. This laborious 10 day process had the effect of creating a strong
alkali by product.
Sodium hydroxide (NaOH), also known as lye or caustic soda, is a caustic
metallic base used in industry, mostly as a strong chemical base in the
manufacture of paper, textiles, and detergents. Due to it's high reactivity,
it must be stored properly in air tight, non porous containers to prevent it
from absorbing CO2 (carbon monoxide) and H2O (water).
Since the ready availability of Sodium hydroxide, by the Leblanc process in
1791, it is the most financially feasible, and readily available alkali for
soap making.
An early soap method was recorded in Yemen (Arabia) The Secrets of Master Alexis of Piedmont, written about 1547. Arabia was making hard soap in the soap boiling method as early as the 8th century, and a document translated reads:
Description of Soap Making
Take two thirds from alkali (al-qily} and one third of un-slaked lime (nura dhakar). Break the lime into small pieces the size of faufal or chestnut. Take a mirkan large vessel} of pottery and cut an outlet (manzil) at its bottom. And seal this outlet tightly with a rag. Take bricks and break them into small pieces, not quite small, and pack them inside the middle of the mirkan. Place on the broken bricks a piece of khsaf. Throw on the khasafa the alkali and the un-slaked lime. And pour on them an amount of water equal to four or five times the submersion volume. The mirkan should be placed on a high position, and we place under the outlet another empty mirkan so that the liquid will flow into it. If there is no high place you will dig a cavity in the ground at a depth equal to that of the empty mirkan, and it is lowered down the cavity so that it is below the outlet. Leave it for one day and one night then open the outlet on the second day so that the filtered water of alkali and lime will pour into it. When all the liquid is emptied, return again and pour it above the alkali and lime and leave it for one day and one night. Open the outlet the next morning and empty the whole clear liquid. When the whole liquid ceases flowing divide it into two halves. Put one half aside. Pour [onto the remaining half] an equal amount of sesame oil (shiraj) and beat (agitate) the mixture strongly and repetitively with a wooden beater for one hour until it hardens and thickens. Leave it for the rest of the day and overnight if you are in a hurry, otherwise leave it for two or three days if you are not in a hurry because the longer it stays the better it ferments. Cool it down and put it in a copper cauldron and set under it a strong fire. Each time it thickens water it with the sharp water from the one half that was put aside as mentioned above. You will continue kindling the fire and watering with the sharp water until it becomes grainy and ripens. Continue beating (mixing) it so that it will not burn. Put it down and pour it into a mirkan (a large vessel) and beat it and water it little by little, then pour it again into the cauldron and place it on fire, let it be a strong fire, and whenever it tends to become dry, water it with the sharp water little by little while you are stirring so that it will not burn. Continue like this until the water is consumed and the soap is well cooked and its consistency becomes like that of the shoemakers glue, known as ashras. Make a milban (mould) from wood, similar to the milban of bricks, but larger. Spread a kham cloth {coarse cotton cloth) or a piece of khasf and place the milban (the mould) over it. Pour the soap into the milban. The purpose of the milban (the mould) is to prevent the soap from flowing until it thickens. Leave it for one night and one day until it solidifies. Then cut it with a knife as is usual. If you want the soap to be perfumed add to it, on the last cooking on fire, choice perfumes and saffron and whatever scents you like then pour it as above mentioned, if God wills. (source: http://www.gabarin.com/ayh/Notes/Notes%205.htm )
Info on Sodium Hydroxide
http://en.wikipedia.org/wiki/Sodium_hydroxide
Info on Sodium Carbonate
http://www.inorganics.basf.com/p02/CAPortal/en_GB/portal/Anorganische_Basen_/content/Produktgruppen/Anorganische_Basen_(Laugen)/Produktinformationen/Soda
A really cool science experiment using Sodium
Carbonate
http://www.newton.dep.anl.gov/askasci/gen01/gen01966.htm
Ancient soap methods
http://www.answers.com/topic/soap
Marius Fabre soap caldroun/boiling method
http://www.marius-fabre.fr/siteen/summary.htm
Solvay method of Sodium carbonate production
http://scifun.chem.wisc.edu/chemweek/Bicarb/SodiumBicarb.html
Chemical process of creating Sodium hydroxide
http://scifun.chem.wisc.edu/chemweek/Cl2&NaOH/Cl2&NaOH.html
More soap history
http://members.tripod.com/~marieainsley/instruction/soap.htm
