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Soap Science

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Use Chemistry to make real soap!
Soap is formed by a chemical process known as saponification.  It is a chemical reaction similar in some respects to the process of mixing baking soda and vinegar; an acid mixes with a base and a nuetral salt is formed.
Three things are necessary to make soap:
  1. Fat (fats are actually acidic)
  2. Lye (or sodium hydroxide, a strong base)
  3. Water (to dissolve the lye)

Materials and supplies:
  • Safety goggles - must be worn.
  • Disposable latex or plastic gloves - another must have.
  • Heat resistant non-reactive container (I have used mason or jelly jars with success, You can also use 12 oz. paper coffee cups but they must be double cupped as a precaution because the lye will start to break the paper down)
  • Lye powder (Click here for source information)
  • Cocoa Butter (obtained from soapmaking supply store)
  • Lard or Vegetable shortening (from the grocery store baking aisle)
  • Hot plate and pan, or a stove to melt the cocoa butter and shortening/lard.
  • Water, cool
  • Plastic disposable spoon
  • Container capable of measuring 2 oz.
  • Thermometer - for measuring temperatues up to 212 degrees F (must be stainless steel, glass or plastic) 
  • molds - use half pint milk cartons, small plastic or paper cups, paper portioning cups/trays - use your imagination.


  • Essential oils, such as lavender, lemon, fake apple, etc. (from soapmaking supply store).  You might also use oil based perfumes or perfumed oils sold for air fresheners.  Ground cinnamon works well, too and is cheap.
  • Oatmeal for beauty bar, cornmeal for Dad's garage soap, dried lavender, etc. 


  1. Safety first.  We are using commercial lye which is a potent caustic agent.  Safety glasses and gloves as well as plenty of adult volunteers supervising is a must.  If lye gets on you flush with fresh water.  Have water for emergency eye wash available.  Be careful, but the project is worth it.
  2. Put on safety glasses and gloves. 
  3. measure 2 ounces of cool water into a heat resistant container
  4.  Add three heaping teaspoons of lye powder and stir until dissolved.
  5. CAUTION:  When Lye mixes with water it generates heat through an exothermic reaction.  It can reach temperatures of 200 degrees Fahrenheit.  It also produces a poison gas so keep your nose away from the container and and use adequate ventilation - an open window or a fan will do.
  6. Let the lye cool to about 95 degrees F.  You can place the container in a vat of cold water to speed cooling.
  7. Melt a mixture of about 50/50 coconut butter and vegetable shortening/lard.  Don't let it get too hot - just hot enough to melt, not too hot to touch.  Measure out about 4 ounces of this into a large plastic cup (like a grande iced latte cup).
  8. Let the fat in the cup cool to about 95 degrees F.  You can place the cup in a vat of cold water to speed cooling.  You can also reheat/cool the fat or lye mixtures to obtain the proper temperatures.  Don't fret too much about exactly 95 degrees - it is a rule of thumb.   
  9. When the proper temperatures are achieved, pour the lye solution into the cup of melted fat, stirring vigorously.
  10. Stir for 10-15 minutes (this is an unbearably long time for kids.  Encourage them to continue, read them the soap science article and soap history facts from this page, blow bubbles,  maybe show an old Bill Nye video or do magic tricks or something).  During the saponification process, the fat and lye will combine to form the soap.  Stirring is necessary to ensure all the molecules are adequately combined.  The molecules need to bump into each other to combine.
  11. When the mixture thickens to the consistency of sour cream, it is ready.  At this point, a drop of the soap will remain on the surface for a second or two.  If it never achieves this consistency after 15 minutes of stirring, then proceed anyway - it will harden overnight. 
  12. Pour the mixture into molds.  At this point you can add a few drops of essential oil, a spoonful of oatmeal, ar other additives to make special soaps.  You can experiment with different types. 
  13. Science Club members can take the soap home at this point.  They will need to keep the soap warm under a towel for 24 hours.
  14. After 24 hours, remove the soap from the mold.  Wrap it in paper and let it season for 2 -3 weeks before using.  Use it in the shower or the tub.  It is a high quality soap, though a little bit strong.  For a milder soap, use less lye and plan on stirring a lot longer.   
  15. Provide kids with the Soap Science Take Home Sheet - so they know that they must cure the soap before using it.

Cautions and safety info: 

  • Tell the kids to keep hands off their skin and faces, if they don't...
  • Have a sink nearby or large bucket with water so kids can rinse lye off their hands.
  • Keep several bottles of water on hand for an emergency eye wash.
  • Thermometers, spoons and containers must be stainless steel, glass or plastic.  Aluminun creates a poison gas in lye.


Soap History                           
Legend has it that soap was discovered during Roman times.  On Mount Sapo (Latin for soap) there was an altar used for sacrificial offering of animals.  Under the sacrificial altar, animal fat combined with lye which rain water leached from the wood ashes of the fire.  Rain washed the naturally occurring soap to the river where the local washerwomen found that the substance sped their cleaning duties. 

Ghastly Soapy Science News
Mummified 'Soap Lady' No Urban Legend
[Original headline: Team unraveling mystery of mummified 'Soap Lady']

PHILADELPHIA [AP] -- Sometime in the 19th century, a fat woman died and her body changed almost entirely into soap.

It may sound like an urban legend, but researchers are serious. On Thursday, they performed a CT scan on the woman's mummified body hoping to learn more about the process that turns some corpses into a waxy, soaplike substance called adipocere.

The body, dubbed "Soap Lady," has been on display for more than a century at the Mutter Museum, a former haven for medical students but now a Philadelphia tourist attraction featuring thousands of medical oddities.

The CT scan unexpectedly revealed some organ tissue, raising hope that researchers might be able to learn how the woman died.

"There's tons of stuff in there," said Gerald Conlogue, a Quinnipiac University professor of diagnostic imaging. "What we may be looking at is a shell or casing made out of this soapy substance sealing out the outside environment."

Conlogue said the results will give researchers greater understanding of saponification, the chemical conversion of fat into adipocere.

Saponification is an unusual occurrence, dependent on factors such as humidity, temperature, the presence of clothing and bacterial activity.

The fatter the person, the greater the chance saponification will occur.

Thursday's scan was the first time the Soap Lady had left her wooden display table since 1874, when a prominent University of Pennsylvania anatomist named Dr. Joseph Leidy donated the body to the museum.

Leidy said that the Soap Lady, who was discovered by workers removing bodies from an old burial yard, died in the late 1700s.

"The woman, named Ellenbogen, died in Philadelphia of yellow fever in 1792 and was buried near Fourth and Race Streets," according to the original label attached to the exhibit.

Leidy's explanation stood until 1942, when museum curator Joseph McFarland determined the Soap Lady had actually died in the 1800s and that her name had been lost to history.

McFarland could find no record of any yellow fever deaths in Philadelphia in 1792. A yellow fever epidemic did strike the city in 1793, but the name "Ellenbogen" appeared nowhere on an official list of the dead. Furthermore, there was never a cemetery at Fourth and Race.

A 1987 X-ray of the mummy showed eight straight pins and two four-hole buttons manufactured in the 19th century.

"At this point, we know less about her than we thought we did before," said Gretchen Worden, the Mutter's current curator.

The CT scan, a computer-enhanced image of areas that cannot be seen by X-ray, was taped for a new television series called "The Mummy Road Show," premiering Oct. 5 on the National Geographic Channel.

The filming made for a bizarre scene: With the television crew and museum workers eating cheese steak sandwiches a few feet away, the blackened mummy slowly passed through a portable CT scanner in a Mutter side room filled with large oil portraits of long-dead Philadelphia physicians.

The Mutter was founded in 1849 by the Philadelphia College of Physicians, which still operates it. Its exhibits include malformed skeletons, a 27-foot-long human colon and a plaster cast of Siamese twins Chang and Eng Bunker.

•Story originally published by:
Contra Costa Times, Walnut Creek / CA | Michael Rubinkam - Sep 29.01

republished from FarShores News

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