Handling and Storage

Section 1: Identification

Product name: soap. A word so common it resists definition. From the Old English sape, from the Latin sapo, which the Romans borrowed from a Germanic or Gallic source — the direction of the loan is disputed, which means nobody knows who named it, only that the name arrived alongside the substance itself, moving west across trade routes with the olive oil and the wood ash and the animal fat from which it was, and continues to be, made.

Recommended use: cleaning of the human body. Also: cleaning of fabrics, floors, surgical instruments, livestock, industrial equipment, ritual objects. As a medium for sculpture. As a unit of currency in certain West African trade networks in the eighteenth century. As evidence, in the soap rations allotted to concentration camp prisoners, of the minimum material conditions a bureaucracy considers compatible with keeping bodies alive.

I keep a bar of it by my kitchen sink. Yellow-white. Olive oil base, probably cut with coconut. It cost four dollars at the co-op. I hold it twice a day minimum and I have never thought about it for longer than the time it takes to rinse my hands. That is the condition this document attempts to address.

Section 2: Hazard(s) Identification

Classification: not classified as hazardous under GHS criteria.

A bar of soap is one of the least dangerous substances for which a safety data sheet can be prepared. The document — designed for sulfuric acid, industrial solvents, compounds that can blind you or stop your heart — is here applied to an object your grandmother kept by the bath.

Signal word: none.

Hazard statements: none required.

Precautionary statements: none required.

And yet. The lye from which soap is made — sodium hydroxide, NaOH — will dissolve organic tissue on contact. A single drop of undiluted lye solution on the skin produces a chemical burn. Swallowed, it destroys the esophageal lining. Lye was the weapon of choice in acid attacks in parts of South Asia and East Africa throughout the twentieth century, though the preferred agent has since shifted to sulfuric and hydrochloric acid, which are cheaper.

The soap in your hand is the aftermath of this violence: fat and lye combined and then cured until the lye is consumed. What remains is the residue of a reaction between a substance that eats flesh and a substance rendered from flesh. Chemically, the soap remembers nothing. Structurally, entirely.

Section 3: Composition / Information on Ingredients

Sodium tallowate (rendered beef fat saponified with sodium hydroxide): 40-60%.

Sodium cocoate (coconut oil saponified with sodium hydroxide): 15-30%.

Glycerin (byproduct of saponification, sometimes removed, sometimes retained): 5-10%.

Water: 10-15%.

Fragrance: variable. Sodium chloride (table salt, added to harden the bar): 0.5-1%.

Titanium dioxide (whitener, in some formulations): <0.5%.

My mother’s hands smelled like Dial soap and Clorox bleach. She cleaned houses in the suburbs north of the city, four houses a day, five days a week, for eleven years. Each house had its own soap. The Bergmanns had a liquid soap that smelled like eucalyptus. The Kohlers kept a cracked bar of Ivory by the utility sink. My mother brought her own — a yellow bar she bought in bulk from a discount store on Route 4 — because she didn’t like the idea that her skin cells were mixed with their soap, her oils on their bar, her body in their house in a way she hadn’t consented to. She washed her hands between every room. By the end of a shift her knuckles were split and bleeding. She called this clean.

Saponification is the word for the chemical reaction that produces soap. From the Latin sapo again. The triglyceride molecule — three fatty acid chains attached to a glycerol backbone — is cleaved by the hydroxide ion. The fatty acid chains detach and bond with the sodium cation to form the soap molecule. The glycerol is released as a byproduct.

Roland Barthes, in Mythologies: “To say that Omo cleans in depth is to assume that linen is deep, which no one had previously thought.” — R. Barthes, Mythologies (1957)

The soap molecule has a hydrophilic head (which bonds with water) and a hydrophobic tail (which bonds with oil and grease). When you wash, the hydrophobic tails burrow into the grease on your skin and the hydrophilic heads face outward toward the water, forming a structure called a micelle — a tiny sphere with the dirt trapped inside and the water-loving surface facing out. Soap does not dissolve dirt. It encapsulates it. It builds a container around the thing you want gone and then the water carries the container away.

My mother did not believe in depth. She believed in surfaces. You could see a clean surface. You could run your hand across it and feel the absence of what had been there. She did not trust products that claimed to work invisibly. She trusted the bar of soap because she could see it shrink.

Section 4: First-Aid Measures

In case of eye contact: flush with water for 15-20 minutes. Remove contact lenses if present and easy to do.

In case of skin contact: no first aid expected to be needed. Wash with water if irritation occurs.

In case of ingestion: rinse mouth with water. Do not induce vomiting. Seek medical attention if symptoms develop.

In case of inhalation: not applicable under normal conditions of use.

Soap is, in almost every circumstance, the first aid measure, not the substance requiring one.

Ignaz Semmelweis, Vienna General Hospital, 1847. He noticed that women in the maternity ward attended by medical students died of puerperal fever at five times the rate of women attended by midwives. The medical students came directly from the autopsy room. Semmelweis instituted a policy of handwashing with chlorinated lime solution before examining patients. The mortality rate fell from 18% to 1.2%. His colleagues rejected the findings. They found it insulting to suggest that a physician’s hands could carry death. Semmelweis was dismissed from the hospital, suffered a breakdown, and died in an asylum at forty-seven. His vindication came fifteen years after his death, when Pasteur and Lister established germ theory. He had no mechanism, only data. The soap worked before the theory did.

D. W. Winnicott, on the transitional object: the child’s first possession — the blanket, the stuffed bear — occupies a space between self and not-self. No one asks the child: did you create this, or did you find it? The question is not supposed to be asked. — D. W. Winnicott, Playing and Reality (1971)

Soap is not a transitional object. But when I wash my hands I am performing a small act of separation: this is me, this is not-me, and the soap is the agent of the distinction.

Section 5: Firefighting Measures

Suitable extinguishing media: water spray, dry chemical, foam.

Unsuitable extinguishing media: none known.

Special hazards arising from the substance: soap burns at temperatures above approximately 300°C. When it burns, it produces carbon dioxide, water vapor, and dense black smoke from the incomplete combustion of fatty acid chains.

In December 2012, artillery shells hit the old souk of Aleppo. The fire burned for days. Among the structures destroyed was the Khan al-Saboun, the soap khan — a stone building that had served as a center of soap production and trade for at least five hundred years. The Aleppo soap industry, which had operated continuously since the eighth century, was the oldest industrial soap-making tradition in the world. Its product — a hard, rectangular block made from olive oil and laurel berry oil, cured for a minimum of eight months — was the ancestor of every Mediterranean soap: Nabulsi, Marseille, Castile.

The soap makers of Aleppo did not disappear. They relocated. Some went to Gaziantep, across the Turkish border. Some went to the suburbs of Marseille, where they found that French soap factories had been closing for decades and the infrastructure — the vats, the drying racks, the long curing rooms — could be rented cheaply. They brought their recipes in their heads. The ratio of olive oil to laurel oil. The temperature at which you add the lye. The precise green of the interior when you cut a properly cured bar. This knowledge — embodied, carried, impossible to destroy by artillery — is the thing that survived the fire.

The soap of Aleppo refuses to stay in one place. A substance made from olive oil and laurel oil by people who have been making it the same way for twelve hundred years, and who, when their city was destroyed, carried the practice elsewhere and continued.

Section 6: Accidental Release Measures

Personal precautions: avoid slipping on spilled soap solution. Wear appropriate footwear.

Methods for containment and cleaning up: absorb with inert material. Flush residual with water.

The first time I washed someone else’s body I was twenty-six. My girlfriend — my partner — she doesn’t like either word, says girlfriend sounds like we’re sixteen and partner sounds like we’re opening a law firm. She had surgery on her shoulder and couldn’t lift her right arm above waist height for six weeks. I washed her hair in the bathtub. I soaped a washcloth and ran it along her back. Her shoulder was still bandaged and I had to wash around it, which meant my hand kept tracing the same path: neck to shoulder blade, a curve around the gauze, down the spine. The gesture became automatic. I stopped thinking about it and started feeling the topography of her back the way you’d read Braille — not letter by letter but as a continuous surface that means something you can’t quite articulate.

She said: “You’re being too careful.”

I said: “I don’t want to hurt you.”

She said: “You can’t hurt me with soap.”

But I could feel the scar tissue forming under the bandage. The body making new material where old material had been cut. The soap running over that place where she was repairing herself, and me unable to tell where the wound ended and the intact skin began.

Section 7: Handling and Storage

Handle in accordance with good hygiene and safety practice.

Store in a cool, dry place. Keep container closed when not in use.

Conditions to avoid: prolonged exposure to moisture (the bar will soften and dissolve). Prolonged exposure to heat. Direct sunlight (fading of fragrance compounds, discoloration).

How to store a bar of soap: on a draining rack, elevated above the wet surface of the sink or shower. Allow air circulation on all sides. A bar left sitting in its own moisture dissolves faster than a bar kept dry between uses. It softens from the bottom up, becoming translucent at the contact surface, losing mass in increments invisible day to day. You notice only when the bar becomes too thin to hold, when it cracks along a fault line you didn’t see forming, when the two halves separate in your hands.

Procter & Gamble, Cincinnati, Ohio. William Procter: a candle maker. James Gamble: a soap maker. They married sisters and their father-in-law suggested the partnership. Candles and soap begin with the same raw material: rendered animal fat. The company was founded in 1837 on the recognition that two domestic products — one that gives light, one that gives cleanliness — share a molecular ancestor.

In 1879, a worker at the Procter & Gamble factory left a soap-mixing machine running during his lunch break. The extra agitation whipped air into the soap base. The resulting bars floated. Rather than discard the batch, the company marketed it. Ivory soap: the soap that floats. The accident became the identity.

Harley Procter, William’s son, commissioned a chemical analysis of Ivory soap in 1882. The chemist found 0.56% impurities. Procter subtracted from 100 and arrived at the slogan: 99 and 44/100 percent pure. Psalms 45:8: “All thy garments smell of myrrh, and aloes, and cassia, out of the ivory palaces, whereby they have made thee glad.” The soap was named after the Psalm. The purity was named after the chemistry. The marketing fused them: grace you could purchase for a nickel.

Ninety-nine and forty-four one-hundredths percent pure. In 1882, while Procter was perfecting this slogan, Chinese immigrants were being expelled from communities across the American West under the Chinese Exclusion Act. The word pure doing double duty — selling soap and selling a nation on the idea that contamination comes from outside, that the foreign substance is the threat, that removal is the remedy.

Section 8: Exposure Controls / Personal Protection

Occupational exposure limits: none established.

Engineering controls: general ventilation adequate.

Personal protective equipment: none required under normal conditions of use. For industrial soap manufacturing: chemical-resistant gloves (nitrile, minimum 0.4mm thickness), chemical splash goggles, long-sleeved clothing. For handling raw lye: full face shield, rubber apron, emergency eyewash station within 10 seconds of the work area.

My mother wore yellow rubber gloves. She bought them in packs of three from the dollar store because they tore at the fingertips within a week. The gloves were not for the soap. They were for the bleach, the ammonia, the oven cleaner — the real chemicals, the ones that burned. The soap she handled bare-handed. She would pull off the gloves between tasks and wash her hands with soap and the thirty seconds of bare-handed washing were the only time her skin touched water without a chemical intermediary. Thirty seconds. Neither protected nor attacked.

There is a photograph, somewhere in a box in my mother’s apartment, of her hands from 1998. She had them photographed for a workers’ compensation claim. The dermatologist needed documentation of the contact dermatitis — the cracking, the redness, the patches where the skin had thickened into something that looked more like bark than flesh. In the photograph her hands are laid flat on a white surface, palms up, fingers spread. They look geological. Eroded. The dermatologist wrote in his report that the damage was consistent with chronic exposure to alkaline cleaning agents and that the condition would likely worsen with continued occupational exposure. The claim was denied. The employer’s insurance argued that the damage could not be attributed exclusively to workplace conditions because she also washed dishes at home.

Section 9: Physical and Chemical Properties

Appearance: solid. Color: white to yellow to brown to green, depending on oil base. Odor: variable, from none to fragrant. pH: 9-10 (mildly alkaline). Melting point: 200-300°C. Solubility in water: slightly soluble. Auto-ignition temperature: >300°C.

A bar of soap is a solid that wants to be a liquid. Its entire purpose is to encounter water and partially dissolve — to release its surfactant molecules into the wash water, where they can do their work of encapsulating grease and dirt. A bar of soap that refused to dissolve would be useless. Its function requires its own consumption. Every use diminishes it.

Every house she cleaned took something from her hands. The soap stripped the oils from her skin. The bleach oxidized her nail beds. The repetitive motion — wringing, scrubbing, gripping — wore the cartilage in her finger joints until her right hand curled slightly inward at rest, as if permanently holding an invisible cloth. The house was clean. The hands that cleaned it were hidden.

Section 10: Stability and Reactivity

Stability: stable under recommended storage conditions.

Conditions to avoid: extreme heat, strong oxidizers.

Incompatible materials: strong acids, strong oxidizers.

The word saponification contains its own stability. Once the reaction is complete — once the lye has been fully consumed by the fat — the resulting soap is chemically inert. It will not revert. The triglycerides will not re-form. The lye will not re-emerge. This is not equilibrium; it is completion. The reaction runs in one direction.

Chemistry offers a version of permanence that biography does not. The soap molecule, once formed, is stable. The soap maker, once displaced, is not. The woman whose hands were consumed by the work, once retired, does not regenerate.

Section 11: Toxicological Information

Acute oral toxicity: LD50 > 2000 mg/kg (rat). Practically non-toxic by ingestion.

Skin irritation: mildly irritating with prolonged or repeated contact. May cause dryness, cracking, or dermatitis in sensitive individuals.

Eye irritation: causes temporary eye irritation. Effects are reversible.

The human epidermis renews itself every twenty-seven days. The outermost layer — the stratum corneum — is composed of dead cells, flattened and stacked like roof tiles, fifteen to twenty cells thick. These cells are called corneocytes. They are filled with keratin and surrounded by a lipid matrix: ceramides, cholesterol, fatty acids. This lipid matrix is what holds them together. It is also what soap dissolves.

When you wash your hands, the soap molecules insert themselves into the lipid matrix between the corneocytes and pull it apart. The dead cells loosen and slough off. This is what clean feels like: the controlled removal of the outermost layer of yourself. You are less after you wash than before. By a layer measured in micrometers. But gone.

Mary Douglas, in Purity and Danger: “Dirt is essentially disorder. There is no such thing as absolute dirt: it exists in the eye of the beholder.” — M. Douglas, Purity and Danger (1966)

Dirt is matter out of place — soil in the garden is earth; soil on the kitchen floor is dirt. Soap, by this logic, is a technology for restoring things to their proper places: oil back to the drain, skin cells back to the water, the body back to its socially acceptable state.

Section 12: Ecological Information

Aquatic toxicity: LC50 (96h, fish) = 1-10 mg/L depending on formulation. Harmful to aquatic organisms.

Biodegradability: readily biodegradable. Degradation by aerobic sewage treatment > 90% within 28 days.

Bioaccumulative potential: not expected to bioaccumulate.

Marseille, 1688. Louis XIV signed the Edict of Colbert, stipulating that only soap made from olive oil could carry the name savon de Marseille. No animal fat. No adulterants. The edict was an early exercise in product regulation — an attempt to standardize quality by limiting ingredients. By the nineteenth century, Marseille had ninety soap factories and produced 180,000 tonnes per year. The harbor smelled of rendered olive oil and caustic soda. Ships carried the finished bars north to Paris, west to the Atlantic colonies, south to North Africa.

Today fewer than a dozen factories remain. Most of what is sold as Marseille soap is manufactured in China or Turkey using palm oil and synthetic detergents. The original product — 72% olive oil, no colorants, no fragrance, stamped with the factory’s name — exists as a heritage item, purchased by tourists and people who believe that a soap made by the old method is gentler on their skin.

Palm oil. The cheapest fat. The one that replaced tallow and olive oil in most commercial soap production after the 1950s. Palm oil plantations are the primary driver of deforestation in Borneo and Sumatra. The orangutan habitat lost to palm oil cultivation since 1990 is estimated at 150,000 square kilometers. Section 12 asks only about the substance’s behavior in the water supply, not the ecological cost of its raw materials.

Section 13: Disposal Considerations

Dispose of in accordance with local, state, and federal regulations.

The soap goes down the drain. It enters the municipal wastewater system, where it is partially broken down by bacterial action. Some fraction passes through the treatment process and enters the waterway — the river, the lake, the estuary. In the waterway, the surfactant molecules disrupt the surface tension of the water. This disruption, at sufficient concentrations, can damage the gill membranes of fish and the respiratory structures of aquatic invertebrates. The soap that cleaned your body becomes, downstream, a toxin.

The SDS format has three more sections. I could fill them.

Section 14: Transport Information

DOT classification: not regulated.

IATA classification: not regulated.

IMDG classification: not regulated.

Soap is not a regulated substance for transport. It crosses borders without paperwork, without inspection. A bar of soap in a suitcase is invisible to customs.

The soap makers of Aleppo carried their knowledge across the Turkish border in 2012 and 2013. They did not carry soap. They carried the process: the sequence of steps, the temperature curves, the timing. A recipe is not regulated for transport either. It has no weight, no volume, no customs classification. You can buy olive oil anywhere. You can buy lye anywhere. You cannot buy the twelve hundred years of practice that tells you when the mixture has reached the right consistency, when to pour, how long to cure.

My mother carried knowledge too. Not a recipe. A set of motions. The angle at which you hold a rag to wring it without splashing. The pressure you apply to a stove burner to remove carbonized grease without scratching the enamel. The order in which you clean a bathroom — toilet, sink, tub, floor — so that the dirtiest surfaces are cleaned first. She learned this from her mother, who cleaned hotels in San Juan. The knowledge went from hands to hands across an ocean. It was never written down and never valued at more than eight dollars an hour.

Section 16: Other Information

Date of preparation: March 2026.

Reason for revision: first issuance.

This safety data sheet has been prepared using information believed to be accurate at the time of preparation. The preparer makes no warranty regarding the completeness or accuracy of the information contained herein. The preparer assumes no liability for any loss, injury, or damage arising from reliance on this document.

The bar by my kitchen sink has become a wafer — translucent at the edges, cracked through the center. I keep using it. I press it between my palms and work it until a thin lather forms, barely enough. My mother would say I’m wasting time. She would say open a new bar. She would be right.