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Lye-Soap-art - 8/8/97


An article on the history of and how to make lye based soap by Baroness Leonora Kathryn de Provence.


NOTE: See also the files: soap-msg, Soapmakng-CMA-art, soapmaking-msg, bathing-msg, Handcream-art, handcream-msg, mirrors-msg, perfumes-msg.





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of files, called StefanŐs Florilegium.


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                               Thank you,

                                    Mark S. Harris

                                    AKA:  Stefan li Rous

                                         stefan at florilegium.org



Lye Soap

Outlands Arts and Sciences Competition

Baroness Leonora Kathryn de Provence



History of Soap


A wonderful myth about the origin of soap is it was a gift to humanity from the Roman Goddess Sapo.  Burnt offerings were made at her temple which sat on a hill overlooking the Tiber River where the women of the village came to wash their clothes. The Goddess caused the rain to wash the ashes and fat down the hill into the river making soap.  The people of the village were blessed by the Goddess with cleaner clothes.


Sumerian clay tablets dated about 2500 B.C. describe using soap to wash wool.  They were found in the area known in modern times as southern Iraq.  A description of a soap formula of water, alkali, and cassia oil was found on another Sumerian clay tablet from around 2200 B.C.  The Babylonians were making soap in 2800 B.C.   The Phoenicians also record using soap around 600 B.C.  The soap was used to prepare wool for dyeing, as the unclean wool was protected by lanolin which had to be removed before the dye would set evenly.


Galen, the Greek physician, recommended bathing with soap for the maintenance of health.  In Pompeii, a fully functioning soap factory was discovered complete with finished bars of soap.  


Hard bar soap, as we know it today, was a luxury in period.  To make soap hard required the addition of salt (sodium chloride).   Pliney, the Roman historian, wrote of making soap from wood ashes and goat's tallow.  He wrote that common salt was added to make the soap hard.  Until the early 1800's when a chemical reaction was discovered that made sodium hydroxide (a source of sodium) cheaply and easily, homemade soap was a soft brown soupy mixture.


Soap was used during period, despite the rumors that people did not bathe. Soap making guilds were documented in Europe in the 7th Century.  The training of craftsmen was jealously guarded and highly regulated. Hard soaps of olive oil were made in the south of France during the 14th Century.  These were of the finest quality and were avidly sought.  In the High Middle Ages, many castles had elaborate facilities for bathing.  In Henry III's palace at Westminster there was hot and cold running water.  Edward II had a tiled floor in his bath and covered them with mats to soak up water and protect him from the cold.  As soap was heavily taxed as a luxury item, it was only available to the rich.  It is believed that public baths were popular until the advent of the Plague, when they were closed as a source of contagion.  Heavy scents became popular after this time.  However, soap was still used in the preparation of fibers.


Soap making equipment was mentioned in a mortgage enrolled in the London court in 1509.  Henry Malyn, "Citezein and Tallough chaundiller of London" mortgaged "his Sope panne, xij Sope fattes wt sij Tappes of iron, a ladle of Brasse and ijSope Coulles (coolers)" to secure money from another chandler.  By 1576,  Elizabeth I commissioned the tallow chandlers to investigate and test all soaps, vinegar, butter, hops and oil in London.


Recipe for Soap:


Clearly, soap for personal use could be purchased.  The soap used for bathing most likely was a commercially made olive oil soap from the south of France. However, for use in the laundry or other chores, the lady of the castle most likely made soft soap.


The process for soap making is fairly simple.  Ashes were collected in a special covered hopper, a finely woven basket, or a bucket. When needed, the woman of the castle would run water through the ashes and collect a dark rough lye.  By very late period, several tests were available to determine what we now call the specific gravity of the lye, which in turn speaks to how strong it is.  An egg was floated in the lye and if only a small coin sized amount showed, it was supposed to be correct for making soap.  In early period, water was run through the ashes, collected and run through once or twice more.  The color of the lye determined the strength.


Fats were collected and rendered to clean them.  The smell from this process is very bad and was usually done outside.  Fatty scraps would be put in a large kettle with plenty of water and boiled for some time.  The kettle was then removed from the fire and allowed to cool.  The clean fat would float to the top and solidify where it was easily collected.


To make soft dark soap, the fats and lye were boiled over an open flame outside.  The mixture was boiled until it became a thick frothy mass which did not burn the tongue when tasted.  This could take up to 8 hours, depending on the strength of the lye.  If the lady wanted hard soap, salt was added at the end as well as any other ingredients such as scented oils or berries for color.


Two period recipes are included for interest.  The English translation these were taken from was published in the Transactions of the American Philosophical Society.  The article title is: Mappae Clavicula : a little key to the world of medieval techniques as translated by Cyril Stanley Smith & John Hawthorne


Mappae Clavicula dates to at least the early 9th century. The version that was translated dates to probably the mid 12th century (possibly early 13th), and is probably from North France or the contiguous areas of Germany.  It contains material of English origin.  The soap recipes exist in this version, not the earlier versions (which are incomplete).  


"280. How soap is made from olive oil or tallow


Spread well burnt ashes from good logs over woven wickerwork made of tiny withies, or on a thin-meshed strong sieve, and gently pour hot water over them so that it goes through drop by drop. Collect the lye in a clean pot underneath and strain it two or three times through the same ashes, so that the lye becomes strong and colored. This is the first lye of the soapmaker. After it has clarified well let it cook, and when it has boiled for a long time and has begun to thicken, add enough oil and stir very well. Now, if you want to make the lye with lime, put a little good lime in it, but if you want it to be without lime, let the above-mentioned lye boil by itself until it is cooked down and reduced to thickness. Afterwards, allow to cool in a suitable place whatever has remained there of the lye or the watery stuff. This clarification is called the second lye of the soapmaker.  Afterwards, work[the soap] with a little spade for 2, 3 or 4 days, so that it coagulates well and is dewatered, and lay it aside for use. If you want to make [your soap] out of tallow the process will be the same, though instead of oil put in well-beaten beef tallow and add a little wheat flour according to your judgment, and let them cook to thickness, as was said above. Now put some salt in the second lye that I mentioned and cook it until it dries out, and this will be the afronitrum for soldering.


288.-D [Making French soap]


Agitate with cold water two parts oak ashes with a third of oak [sic] lime.  Afterwards when they are well stuck together, put the whole in a basket, strongly pressed down to make on top a place for water so that it does not run away. In this you will put cold water two or three times according to the amount consumed by the underlying ashes and the lime. Not quickly but on the following day, the water will drip down onto leaves of laurel or the like placed underneath, so that later it may flow off into another pot, and this is called the capitellum.  Now, if you want to make soap, put in a second water following the first, and when that has run down, put in also a third, and it will be good until it becomes white. Afterwards, melt some tallow, strain it, and when it is strained and cleaned on top if necessary,boil it with the last water. When it becomes thick, put in some of the second water and also some of the first. Or else if you soak ground poplar berries for a day [inthe mixed lye and tallow] and afterwards squeeze and discard them, the soap will be reddish and better. This is French soap and spaterenta, i.e., sharp."


I have made boiled soap from scratch as a docent at the Living History Farmin Des Moines, Iowa.  It is nasty stuff, deep brown and hard.  It was not a soap that I would put my hand to.


Modern Batch Soap Making

The method I used for making soap is completely modern. It is a non-boiled method developed in the 19th century.  The lye is purchased white and pure from the grocery store plumbing section.  The fats component contains a small amount of coconut oil to make it lather, olive oil, and either pure white shortening (which makes avery white and hard soap) or pure clean white lard (which makes an antique white soap which is slightly shiny and waxy).  The result is a mild pure bar which is a delight to use.


Supplies needed:  2 slotted wooden spoons, large glass jar, long rubber gloves,  safety glasses, stainless steel or enamel pan, thermometer that reads accurately in the 90 to 100 degree range, plastic or glass soap mold with straight sides and a cover (I use a plastic Rubbermaid container with a snap-on lid), plastic wrap, several wool blankets, and a small amount of thin wire.  Avoid aluminum in the soap making process, as the lye will dissolve it.


2 cups cold filtered water

1/2 cup of pure lye (Red Devil Pure Lye from the plumbing section of the

grocery store)


When handling lye, use long rubber gloves and safety glasses.  Lye is a vigorous caustic which can do terrific and permanent damage to eye tissue and cause deep and severe burns to skin.


Put the water in a large glass jar.  Slowly add the lye to the water.  Stir with a wooden spoon.  The mixture will heat up and may emit some irritating gases.  Do not breathe the fumes from the lye!  Cool the mixture in a cold water bath until the mixture is between 90 and 100 degrees.


1/2 cup coconut oil

3 and 1/2 cups fat comprised of olive oil, shortening, lard, or other fats- the greatest part needs to be a solid or hard fat but the oils can be added for a soft, rich bar.


In the pan, melt the fats over medium heat, stirring and watching carefully.  When the hard fats are just about all melted, remove from heat.  Cool until between 90 and 100 degrees.


When testing the temperature of either mixture, first stir completely as they can stratify.


Grease the soap mold very thickly with a solid fat.  You may want to line the mold with plastic or special soap makers' parchment so that the soap comes out to the mold cleanly.  It is not necessary, though.


When the two mixtures are within 5 degrees of the same temperature, wearing your gloves and glasses, slowly pour the lye into the oils stirring carefully.The oil should immediately start to get cloudy and opaque. Stir for at least five minutes or until the soap starts to thicken and "trace".  To determine if the soap is "tracing", drizzle a stream of soap over the surface with the stirring spoon.  If the stream leaves a trace of it's passing on the surface of the soap, it is done.  The amount of time you need to stir will vary.  It may vary from batch to batch using the same exact recipe!  It will eventually, just keep stirring until it does.


After the soap traces, then add essential oils, herbs, or grains.  I generally add a tablespoon or a little more of essential oils to one batch.  I add 1/4 cup of finely ground herbs or 1/2 cup of finely ground oatmeal.  Work quickly as the soap is in the process of setting up.  Oatmeal seems to really accelerate the process.  Mix very well and quickly pour into the prepared mold.  You may cover with more plastic wrap and smooth the surface with your hands, or just smooth it with the spoon back.  


Cover the soap and put in a nest of wool blankets to cure for around 18 hours.  It make take longer or shorter.  Batch soap making is not an exact science!  When is has set up and is somewhat firm, it is ready to turn out and cut.


I turn the soap out onto a flattened plastic grocery bag. The mess after cutting can just go into the trash.  The soap is still extremely caustic so wear gloves and safety glasses when handling.  I cut the large lump of soap into bars with wire.  It is messy, but if pieces flake off, you can push them together.  I then smooth the sides with my hands.  You can also form the soap into balls, or form a soap ball around a knot in the bottom of a loop of ribbon or rope for a "soapball on a rope".


Put the soap bars onto glass or plastic to air cure for at least 2 weeks. Turn them at least once at the mid-point.  The soap will become harder and harder and change color slightly.  The soap should end up around pH 8 which is fine for skin.




The batch soap making method creates a soap which is more like the soap that was available in period from professional soap makers of Southern France.  The soap the lady of the castle would make was a different product, more likely to be used for washing clothes and cleaning.  It does bring one close to the soap maker of the Middle Ages.  It is not an exact science and even using modern tools and ingredients, soap still occasionally fails to turn out correctly.  While it is frustrating when a batch fails, it also reminds you that there are things you just can't control or really understand at work.  And that is, truly, a very medieval mind set.





The Soap Book,  Sandy Maine, 1995.  Interweave Press.


"The Compleat Anachronist #68  Domestic Lighting: Candles, Lamps, and Torches in History."  Dennis R. Sherman, 1993. Society for Creative Anachronism, Inc.


"Colonial Soap Making.  Its History and Techniques."   Marietta Ellis. Downloaded from the Internet.


"Mappae Clavicula : a little key to the world of medieval techniques".English translation by Cyril Stanley Smith & John G. Hawthorne.  Transactions of the American Philosophical Society, n.s. v.64, pt. 4, 1974.


Life in a Medieval Castle,  Joseph & Frances Gies, 1974.  Harper & Row



Copyright 1997 by Sheron Buchele, 7743 West First Street, Loveland, CO 80537.

970/669-3835 (foxryde at verinet.com). Permission granted for republication in SCA-related publications, provided author is credited and receives a copy.


If this article is reprinted in a publication, I would appreciate a notice in

the publication that you found this article in the Florilegium. I would also

appreciate an email to myself, so that I can track which articles are being

reprinted. Thanks. -Stefan.


<the end>

Formatting copyright © Mark S. Harris (THLord Stefan li Rous).
All other copyrights are property of the original article and message authors.

Comments to the Editor: stefan at florilegium.org