The Holocaust Historiography Project

Nazi Human Soap Manufacturing

A Report on the Mazur Statement (Nuremberg Document USSR-197)

by Robert Frenz

About the author

Robert Frenz has a Bachelor of Science degree in Mathematics, and a Master of Science degree. He was at one time the proprietor of Lume Products Co., a duly registered company engaged in the manufacture of specialty soap products (no longer in existence). He has nearly 10 years experience as a process chemist in the aerospace industry, experience as a chemical technician in a U.S. Army poison gas manufacturing facility, experience as a chemical technician in a hafnium/zirconium separations facility, and experience as a chemical technician in a gold extraction facility. He is also the formulator of a hydrocarbon-based soap emulsion, the manufacturing rights to which were sold to Diamond Glo Products, Inc.

The Products: Soap and glycerine

Soap, in the generic sense, usually means a mixture of the sodium salts of oleic, palmitic, and stearic acids. Only rarely do we encounter a soap as a pure chemical compound. An example would be sodium oleate (Eunatrol) with a melting point of 232 degrees Celsius.

In a broader meaning, soap is the salt of a carboxylic acid having from 10 to 18 carbon atoms in its molecular chain. In addition, there are potassium soaps. Potassium soaps are called “soft” soaps while their sodium counterparts are called “hard” soaps.

There are ammonium soaps, triethanolamine soaps and morpholine soaps. These are widely used as emulsifying agents. Calcium and magnesium soaps are responsible for the unwanted and familiar “bath tub ring.” Zinc soaps are used as water and solvent barriers. Aluminum soaps have been used as varnishes.

For the purposes of this study, the term “soap” will mean the sodium salt of oleic, palmitic, and stearic acids. This is in accord with common parlance.

When applied to soap, the adjectives soft and hard refer to chemical composition. A layman, upon reading a recipe for making “hard” soap would more than likely interpret this in a physical sense. In this understandable case, the person would be in error. Soap is always “soft” in the physical sense as its normal state is in the amorphous form. Soap may be prepared in crystalline form as pure and separate compounds, i.e., as sodium oleate, sodium palmitate, and sodium stearate. With the exception of pure sodium stearate, the other constituents of ordinary soap are not white in color. Crystalline sodium palmitate is reddish brown in color. The amorphous form of sodium oleate is distinctly yellow in color. Thus, any mixture of these three, as is always the case outside of a laboratory, will never be white in color. It varies from an amber to a brown color.

When one thinks of “pure” soap, I would assume that the brand name “Ivory” would come to mind. Ivory soap is not white because it is pure nor because it is soap. Crisco cooking fat is not white because it is pure nor because it is fat. Both of these common items are white because they have been processed to incorporate a considerable volume of air. Carefully melt some Crisco and let it solidify. You will observe that its natural color is tan. It is possible to melt Ivory soap without decomposition, but it is difficult. If one has the laboratory equipment to perform this, he would find that Ivory soap, that lily-white stuff, is actually an amber or tan color. Soap is never white in color. It may be made to appear that way only through special processing. Ivory soap floats in water due to this incorporated air. [note 1]

An important by-product

The most widely used method for the production of soap involves a composite hydrolysis and neutralization reaction called saponification. The saponification of animal fats and vegetable oils also produces considerable quantities of glycerine.

Glycerine is an important alcohol that has a value greater than that of its coproduct soap. Glycerine is used on the manufacture of nitroglycerine, dynamite, blasting gelatin, and the smokeless powders Cordite and Ballistite. Modern wars have been essentially an exercise in the use of explosives and governments have placed a premium upon the production of glycerine. Until 1948, all glycerine was derived from the saponification of animal fats in particular. Thus, during World War II, housewives were encouraged to save all used cooking fats. Those who remember the period will also be aware of soap scarcity.

It cannot be overemphasized that during a period of military conflict, the use of fats for the production of explosives is of far greater significance than the laundry or toilet comfort of the population.


Soap has been known since early Roman times. France was using crude soaps as early as 100 A.D. In Italy, soap making was developed into an art about 700 A.D. The making of soap is not a simple matter of tossing some fat and lye into a kettle, boiling, and serving up as one would a bowl of soup. The early soaps were very crude. They either didn’t clean well or they irritated the skin. There was considerable “consumer” reluctance in regard to their acceptance. Effective soap production involves considerable skill. While it is very easy to jot down the equation for some chemical reaction, it remains quite another matter to get it to work.

Recipes for making soap abound as do recipes for the making of fudge. However, rare is the cook who can make fudge that isn’t grainy, hard as a rock, or simply a pool of chocolate sauce. Making candy, as well as making soap, is an art.

Fat and Lye

Two of the main ingredients in the making of soap are sodium hydroxide and animal fat. Sodium hydroxide is often referred to as lye, caustic soda, on simply soda. This is not to be confused with soda ash (sodium carbonate) or acid soda (baking soda, i.e., sodium bicarbonate). Soda ash is also known as washing soda. Lye is used to saponify fats for the production of glycerine and soap.

Lye is commercially manufactured by the electrolysis of common salt (sodium chloride). It is a white solid with a powerful affinity for water. It will remove the water from the air and dehydrate many organic compounds. It is destructive of living tissues and will cause severe “burns.” It is destructive to paints and has been used as a paint remover. Lye reacts readily with aluminum and zinc, and is a hazardous substance.

Animal fats are essentially the glycerol esters of oleic, palmitic, and stearic acids (fatty acids). They are usually referred to as olein, palmitin, and stearin, respectively. Animal fats are obtained during meat production.

Fats are widely distributed throughout the body. The largest concentrations occur about the kidneys and below the surface of the skin. Fat is supported within the body by cell structures that involve from 15 to 20 percent of the total mass. Thus, 100 grams of fatty tissue contain from 80 to 85 grams of fat. It should be emphasized that there is an essential difference between fat and fat tissue. Fat tissue is not suitable for direct use in the manufacture of soap and glycerine.

Sources of fat

The fats are separated from the unwanted tissue by a process called rendering. This involves the grinding up of the fat tissue and the melting of the fat using steam. A filtering process allows the passage of the condensed steam and the molten fat. Because water and oil do not mix, the liquid fat is left floating upon the water where it is easily separated.

Small batch methods usually involve boiling water to effect the melting of the fat. Grandma would grind up the hog fat and boil it with a quantity of water. Fat may also be rendered by direct heating. This necessarily involves greater temperatures which cause some decomposition and discoloration. This is a frequent process in our kitchens. It is called frying. The fat is cooked out of the bacon. Fat obtained in this way will yield strongly discolored soap as evidence by the brown color of Grandma’s lye soap.

Beef suet contains about 25 percent olein and about 75 percent palmitin and stearin. Lard (hog fat) contains about 60 percent olein, the remainder being stearin and palmitin. Olive oil contains about 75 percent olein and 25 percent palmitin and stearin. Olein produces physically softer soap than stearin.

The iodine value of a fat is a measure of the degree to which it is unsaturated (double and triple bonds between the carbon atoms). The saponification value of a fat is the number of grams of potassium hydroxide needed to exactly saponify one kilogram of that fat. Lard and human fat are very similar. They have nearly identical iodine and saponification values. For purposes of discussion and processing, they are interchangeable. Lard has a saponification of 196. The saponification value relative to sodium is 140. Lard has a specific gravity of 0.9 and a melting point under 65 degrees Celsius.

Unlike lye, lard is not hazardous. We eat it, and it often occurs in homemade ointments.

The Reaction

It requires 140 grams of soda and 1000 grams of lard to produce 1033 grams of soap and 107 grams of glycerine. The 107 grams of glycerine my be used to produce 254 grams of nitroglycerine. With the addition of 442 grams of water, the 1033 grams of soap become 1475 grams of usable soap. All soaps commonly used contain nearly 1/3 water. A bar of soap weighs about 150 grams. Therefore, 1 kilogram of fat has an equivalent of 0.254 grams of nitroglycerine and 10 bars of soap.

As with a juggler’s act, soap making is easy to describe but difficult to perform. There are two general methods of soap manufacture. The one called the “cold” process requires less expertise and equipment. The “hot” process is reserved for larger controlled operations where quality is important and the by-product glycerine is to be further utilized. In the cold process, the glycerine is retained in the finished product. There also exists a bastardized method that I shall call “Grandma’s method.” This was the old kettle method of days past.

As with all methods, the fat was obtained by rendering the products of slaughtering. The visible fat being ordinarily used although Grandma also used the “drippings” from a varied range of cooking methods.

Grandma’s Method

The potash was obtained by the leaching of the ashes from the fires. Technically this is not potash, but a mixture of alkaline carbonates that served as soda. The strained liquid was placed in a kettle with rendered fat and simply boiled down to a syrup. It was then poured into a frame for cooling. How much water, ashes, and fat that went into this pottage was Grandma’s educated guess. Some Grannys made passable soap, but many others manufactured paint removers. Generally, these soaps were quite caustic but nonetheless proved invaluable for scouring the cabin floor.

Incidentally, soaps containing a slight excess of soda are the laundry soaps while facial or body soaps have a slight excess of fat.

The Cold Method

This is a considerable improvement over Grandma’s method. It involves the reasonably exact measuring of the quantity of fat, water, and soda. The soda is dissolved in the water and added delicately to the warm and molten fat. If the soda is added too briskly, the materials become transformed into an undesirable mess. If properly executed, one obtains a decent, glycerine enhanced soap. One supplier of soda (lye) lists a recipe on the can and after one or two falling attempts, one becomes adept.

Water and fat do not mix and the reaction between soda and fat is not rapid.

The Hot Method

This method is best suited for continual production where the recovery of the glycerine is desired. Steam is used as the source of agitation, water, and heat. The rendered fat is fat into a vat containing 2 to three times its volume of a 6 percent soda solution. It is continually boiled and mixed until a visual inspection reveals that considerable soda has been “taken up.” Brine is then added to force separation. This stage is called “graining” or “opening.” The aqueous phase contains salt, unspent soda, and glycerine. This is fed off for glycerine recovery. The remaining fat and soap, that which has floated to the top during the settling stage, is then subjected to “strengthening.” This is similar to the first cycle except that the soda solution is about 16 percent. After this second cycle, the soap contains residual soda and has to be further processed to remove it. Following each separation or settling, there are further operations, all taking place on a continual basis.

Since 1945, soap manufacture has been drastically modified. Since 1948, glycerine production has not depended entirely upon naturally-occurring fats.

The Spanner Recipe

This recipe occurs in the Mazur document on page D, first paragraph. As written, it is problematic to follow:

Lines 1 and 2: Does one add 500 or 1000 grams of soda?

Line 5: A handful of soda is about 50 grams. Why so little in proportion? Soda is caustic. Does one use his bare hands?

Line 7: How does one know the soap is “finished?” Was the soap liquid so that it might be “poured?”

This recipe appears to be the hot process. I followed this recipe as best as I could and in proportion on a smaller scale. As mentioned in this report human fat and lard are quite similar so I necessarily used lard. I failed to produce other than a trace amount of soap.

On another occasion, I again followed this recipe to no avail. As written and as followed by myself, this recipe has no value. I attempted a vigorous boiling during the second stage, but this merely filled the air with caustic fumes and caused considerable consternation on the part of my wife when she surveyed the condition of the kitchen range.

The Conclusion

Contradictions and errors in the testimony concerning soap:

1. Page D, line 8: Benzaldehyde was used to eliminate the unpleasant smell.

1.a. Page I, last line: The soap had a bad smell.

Question: If the smell was eliminated, why was it still there?

2. Page I, line before last: Homemade soap is never physically “hard.” It is quite soft mainly due to the unavailable water incorporation. Commercial soaps have to be processed by reducing water content and pressing into molds in order to make them physically hard.

3. Page I, lines following *: This is patently absurd. Caustic soda is extremely corrosive. Adding it to rather bland fat could in no way enhance its blandness.

4. Page B, last lines: Mr. Mazur worked as a courier for 3 months starting in January 1941.

4.a. Page C, line 3: Mr. Mazur was appointed as a lab assistant in January 1941.

Question: Did Mr. Mazur experience a time warp?

5. Page D, lines 6-7, paragraph 5: The guillotine was in the yard and at the same time, in one of the rooms.

Question: Are yards customarily located in rooms?

6. Page I, bottom: Soap is never white in color. It is always a tan to dark brown in color depending upon its chemical composition and the purity of the fats used. See my discussion on page 3.

7. Page D, line 7: “… the soap was poured out into moulds.”

7.a. Page I, last lines: The soap was in the shape of a “lump.”

Question: How did the soap, which was poured into some shape (mould) become a “lump” when it arrived at Mr. Mazur’s house?

8. Page E, paragraph 7: “… the production of soap from human fat must be kept secret.”

8.a. Page G, bottom lines: The recipe was apparently posted conspicuously.

8.b. Page I, line 6 of answer: Mr. Mazur’s mother as well as his sisters were told “everything.”

8.c. Page E: Most of this page is a recitation about colleagues, students, and professors from other medical institutes all receiving soap and information.

8.d. Page C, paragraph 3, paragraph 5: Two more persons obviously privy to the soap business.

Question: Here we are faced with a “secret” which was not only conspicuously posted in writing, but was known by everyone. Who didn’t know about this “secret?”

More Questions

1. Page D, paragraph 7: What was the purpose in collecting this sort of data? Does the quality of soap depend on one’s surname and/or date of birth?

2. Page C, paragraph 2: Spanner departed to the southwest a distance of about 600 kilometers. Halle is near Leipzig. As the Soviets entered Warsaw on 11 January 1945, his departure was timely. The Soviets reached Berlin on 22 April 1945. Dr. Spanner had the foresight to bring along a companion. Page C, paragraph 5. Dr. Spanner obviously knew what was “going down” and Mr. Mazur apparently was oblivious to it all as he was carrying soap home during the months of February and March. Page I, Answer.


It was earlier pointed out that the fat must be separated from the supporting tissue. Nowhere in the document is there any reference to this process. We are led to believe that fat was excised from corpses and tossed into the boiling pot in a manner fashioned after soup making. Typically, fat is mechanically separated from bone and the supporting tissue, before being ground up to increase its surface area.

According to Mazur, it took 40 corpses to produce 80 kilograms of fat that subsequently yielded 25 kilograms of soap. This is equivalent to 4 bars of soap per corpse. It was obviously a very shoddy operation. Theoretically, 80 kilograms of fat should produce somewhere near 800 bars of soap (20 bars of soap per corpse), and with additional processing ½ kilograms of nitroglycerine. Are we to assume that Dr. Spanner and the Institute were more interested in cleanliness than in fighting a war? The Americans were busily using their fats for the production of explosives but the Institute seemed to have a dirt problem. It appears rather ludicrous that a project was set up for the purpose of making soap rather than utilizing the fats for the production of glycerine.


It is my belief that the testimony in regard to the making of soap from corpses is false. The recipe appears to be gleaned from some source without regard to the practical limitation of putting it into practice. I doubt whether Mr. Mazur had any knowledge whatsoever about the technique of soap making. A novice could not possibly make soap following such directions as the Spanner recipe. Experienced soap makers would view the recipe as too sketchy to be of use. In fact, the first settling stage would find the soap at the bottom of the unreacted fat and not at the top as Mr. Mazur remarks. Soap is denser than water with a melting point near 300 degrees Celsius and could never be “poured out into molds” as a finished, cold product. Furthermore, if one was seriously interested in making soap from all available fat, the process selected would have been the cold process. Because the Spanner recipe calls for materials by weight, it is therefore possible to weigh out the fat, soda, and water and dispense with the pointless mess obtained by hours of boiling. The cold process will have a batch of soap in the molds in less than one hour. It could then be stored for curing and suitable for use in a few days. I would assume that any doctor heading an anatomical institute would be somewhat better informed in regard to topics such as this. The information is so widespread that it is superfluous to cite references.

It is a conjecture on my part, that whoever perused the soap-making literature found a recipe for “hard” soap and believed this to be a physical state instead of a name for sodium soaps. This would explain the glaring error which adds to the emptiness of the document. Mr. Mazur never handled, much less made, a “hard lump of white stuff” that was the result of any soap-making activity. The only explanation I can offer is that he was supplied incorrect and cursory information by a person or persons unknown that was obtained by an uneducated reading of the hot process of making “hard” soap, ample descriptions of which are readily available. He then continued with the weaving of a story that had no basis in fact other than an obvious one: it is possible to make soap from human fat.

My effort, in the review of this document, has left me convinced and of the opinion that Mr. Mazur never made soap out of any kind of fat. I also have a serious doubt, of the greatest magnitude, that Dr. Spanner ever wrote any soap recipe.

Appendix A: Record of examination 28 May 1945

[This document is also known as USSR-197, and is referred to in the Nuremberg court transcript of 19 February 46, IMT VII, starting on page 597]

In Danzig on 28th May 1945, the Judge-Advocate of the rear services of the Second Byelorussion Front, Lieutenant-Colonel Geitman of the legal service, and the investigating Officer of the Judge-Advocate’s Office of the Second Byelorussion Front, Major Kadensky of the legal service, examined the undernamed person as a witness, and he gave evidence: Zigmund Yuzefovich Mazur, born in 1920, native of Danzig, a Pole who received German citizenship in January 1944; completed 6 classes of the Polish “gymnasium” (grammar school) in Danzig in 1939; voluntarily served as a soldier in the Polish army in 1939; a clerical worker; unmarried, according to his declaration, not previously convicted; he lived at no. 2, Betschergasse, Danzig, and was employed until April 1945 as a laboratory assistant at the Anatomical Institute of Danzig; his mocther lives in Danzig at no. 10, Neuschottland Street; he has a command of the Polish and German languages.

The testimony is translated from Polish into Russion by the interpreter of the Danzig Commandant’s Office, Boguslava Kostinova. The word “German” has been altered to “Polish,” which should be taken as the correct version.

The interpreter was warned of her liability for refusing to translate and for giving a false translation under Articles 92 and 95 of the Criminal Law Code of the Soviet Federal Socialist Republic.


In October 1940, while in Danzig, I was looking for work.

The German official Gustav Lange from the Danzig employment office, to whom I had given one of the rooms of my flat, promised to find me a better, more suitable job in one of the educational establishments of Danzig, and after this Iwas sent to the Anatomical Institute of Danzig, where I began work in January 1941. At first I was working as a courier for three months. While working as a courier, I began to take an interest in medicine, and with the help of Lange and Professor Spanner, I was appointed to the post of laboratory assistant at the Anatomical Institute, from January 1941. My duties as laboratory assistant included drawing charts and assisting in the dissection of corpses.

The Director of the Anatomical Institute was a German from the town of Kiel, Professor Rudolf Spanner, who left for the area of the town of Halle in January 1945.

Professor Spanner’s deputy was a doctor, Senior Lecturer Wollman — he was an SS officer, but wore civilian clothes, and sometimes black SS uniform. Wallmon was from Czechoslovakia, and his Czechoslovakian surname was Kozlik.

In January 1945 he voluntarily entered the SS forces.

From October 1944, a woman, Fosbeck from Doppot, was working as an assistant. She left for Halle with Professor Spanner. She was doing post-graduate work with Professor Spanner.

The senior laboratory assistant was von Bargen, who came to Danzig from Kiel with Professor Spanner.

The attendant for laying out corpses was a German, Reichert from Danzig, who left in November 1944 to join the German army. Borckman, a German from Danzig, was likewise an attendant, but I do not know where he is now.

Q: Tell us how the soap was made out of human fat at the Danzig Anatomic Institute.

A: In the courtyard of the Anatomic Institute a one-story stone building of three rooms was built during the summer of 1943. This building was erected for the utilization of human bodies and for the boiling of bones. This was officially announced by Professor Spanner. This laboratory was called a laboratory for the fabrication of skeletons, the burning of meat and unnecessary bones. But already during the winter of 1943-44 Professor Spanner ordered us to collect human fat and not to throw it away. This order was given to Reichert and Borkmann.

In February 1944 Professor Spanner gave me the recipe for the preparation of soap from human fat. According to this recipe 5 kilos of human fat are mixed with 10 liters of water and 500 or 1000 grams of caustic soda. All this is boiled 2 or 3 hours and then cooled. The soap floats to the surface while the water and other sediment remain at the bottom. A bit of salt and soda is added to this mixture. Then fresh water is added, and the mixture again boiled 2 or 3 hours. After having cooled the soap is poured into molds.

1. I have found only one reference (Noller) in regard to the composition of human fat. He gives 5 percent stearin, 35 percent palmitin, and 60 percent olein. Stearin soap is the lightest in color (although more difficult to manufacture), palmitin soap is yellow, and olein soap is yellow-tan to yellow-brown. Commercial oleic acid is known as “red oil.”