Glossary

Soap Making Glossary
We have compiled a list of terms, acronyms, and definitions used throughout the Soap Making and HandCrafted Industries.
Although this glossary is extensive, it is a work in progress. We can't guarantee that every definition is 100% accurate.

A

Absolute
A concentrated, highly aromatic, oily mixture extracted from plants. Absolutes are free of by-products and waxes and are alcohol soluble. They are separated from the plant, by using alcohol and vacuum distillation.

Acid
A solution having a pH of less than seven. (See pH definition)

Acrylamide Copolymer
Acrylamide Copolymer is a thickening agent. 

Additives
Referring to soap; the more expensive oils, usually added in small quantities and considered superfatting oils, medicinal oils, tinctures, herbs, clays, and other substances that enhance the overall quality.

Alcohol Extract
A concentrated herbal tincture. Alcohol can be used as a solvent to extract herbal compounds.

Alkali
A substance with a ph higher than 7. An Alkali can be used to neutralize an acid. Sodium hydroxide is an Alkali and is used to make soap.

Alkali Salts
Salts which contain one or more hydroxide ions. Examples of Alkali Salts used in our industry are Sodium Hydroxide (Caustic Soda, Lye) and Potassium Hydroxide (Potash).

Almond Oil
Almond oil is obtained from the nut, which botanically, is actually a fruit. Almond oil is used in skincare preparations as an emollient or as a carrier oil.

Aloe Vera
The juice or gel obtained from the leaves of this plant can be used in cosmetics. It is known for its soothing and healing properties.

Amber
A resin obtained from fir trees, which gives a warm, woody scent.

Anhydrous
A liquid or a compound that does not contain water.

Antioxidant
Inhibits or retards the reaction of a substance with oxygen(oxidation). In addition to their many uses in medicine, antioxidants have many industrial uses, such as preservatives in food and cosmetics and preventing the degradation of rubber and gasoline.

Apocrine
A type of sweat gland in the human body that determines a person’s body odor, which affects the way a scent smells on a person.

Apricot Kernel Oil
Derived from the seeds and known for its moisturizing properties. It is used in skincare preparations.

Aromatherapy
Aromatherapy is the use of essential plant oils (Essential Oils) or aromatic compounds from plants for the purpose of affecting a person’s mood or health.

Aromatic
Having a strong scent or fragrance.

Ascorbic Acid
A sugar acid with antioxidant properties. Its appearance is white to light yellow crystals or powder. It is water-soluble and is commonly known as Vitamin C in tablet form.

Astringent
A solution that constricts or tightens the skin and also removes oils. It is often used in facial preparations. 

Attar or Otto
Is the Essential Oil extracted from the petals of various types of rose.

Avocado Oil
Oil from the pulp of the fruit.  Avocado is high in unsaponifiables and is used in cosmetics and skincare preparations for its moisturizing and nourishing properties.

Awapuhi Kuahiwi
Also known as shampoo ginger or Hawaiian wild pinecone ginger. Awapuhi Kuahiwi originated in India. The thick, sudsy juice squeezed from the mature flower head is used as a shampoo or hair conditioner.

B

Balsam
A term used for various pleasantly scented plant products; Balsam Fir, Balsam Flower (Impatiens), Balsam Poplar, Balsam of Mecca, etc.

Base Oils
Referring to soap; also known as Fixed Oils, the main oils that make up the main soap formula, Palm, Coconut, Olive, Soybean, Sunflower, etc. Oils such as Castor, Coco Butter, Jojoba, etc, would be additives.

Bath Bomb
A blend of Baking Soda (Sodium Bicarbonate), Citric Acid and sometimes other ingredients which produce a fizzing action (effervescence) in bathwater. These usually contain Essential or Fragrance oils and moisturizing oils. Also known as Bath Fizzies. There are many forms, for example; balls, tablets, and cubes.

Beeswax
This is obtained by brave persons who don’t mind getting stung once in a while. After absconding with the honeycomb, by either doping the bees with smoke or going in cold turkey, they separate the honey from the comb and then meltdown and filter the resulting wax into blocks or billets. In the Body Care Industry, beeswax is used in candles, soaps, lip balms, butters, etc.

Biodegradable
A substance that is able to be decomposed by living organisms, such as bacteria, enzymes. Organic material can be degraded aerobically, with oxygen, or anaerobically, without oxygen.

Biopein®
Biopein is a natural preservative and stabilizing ingredient which is manufactured from a synergistic blend of botanical extracts.

Bleaching
Is the process to remove or neutralize the color of an oil or fat. This can be done with clays, carbon filtering, and other methods.

Borax
Also known as Sodium Borate, Sodium Tetraborate, or Disodium Tetraborate. It is a white crystalline mineral, generally used as an emulsifier or cleanser. It can be used in cream preparations as an emulsifier.

Botanical
A substance obtained from a plant or plants, related to plants or botany.

Botanical Name
The Latin scientific name of a plant assigned to distinguish one species from another. The scientific name is composed of the genus followed by the species.

C

Carrier Oil
This is also known as a base oil or vegetable oil. It is used to dilute essential oils and absolutes before they are applied to the skin. They are so named because they carry the essential oil onto the skin. Carrier oils do not contain a concentrated aroma, unlike essential oils, nor do they evaporate like them. Examples: Sweet Almond, Grape Seed, Olive Oil, Sunflower, Emu Oil, Peanut, Pecan.

Castile Soap
Originally, soap made only from Olive Oil and so named because it originated in the Kingdom of Castile. However, now Castile is sometimes used to refer to any type of mild soap.

Castor Bean Oil or Castor Oil
Derived from the beans of the Castor plant. Castor Oil is a colorless to very pale yellow liquid with a mild to no odor or taste. It has a number of medicinal uses. In Soap Making it is used in small amounts as it can react with other oils. See also Turkey Red Oil.

Caustic Potash
See Potassium Hydroxide.

Caustic Soda
See Sodium Hydroxide.

Chandler
Generally a maker (and seller) of candles and soap, however, this can refer to anyone retailing special provisions and supplies.

Chlorophyll
This is a green pigment found in most plants and algae. Chlorophyll absorbs light most strongly in the blue and red but poorly in the green portions of the electromagnetic spectrum; hence the green color of chlorophyll-containing tissues like plant leaves. It is used in soap as a coloring and may give the soap some antiseptic properties.

Chypre
Is the name used to describe a family of scents, generally based on a top note of citrus and woody base notes, such as Clary Sage, Oakmoss, Patchouli, etc?

Citric Acid
Is a weak organic acid. It is extracted from citrus and other acidic fruits such as pineapples. It can be used as a flavoring and preservative in foods and beverages; also used in bath products. It is known in our industry, primarily for making Bath Bombs.

Citrus Scent
From the family of scents, based mostly on Orange, Lemon, Lime, Mandarin, Neroli, Grapefruit, and Bergamot.

Cocamide DEA
A viscous liquid used as a foaming agent and emulsifier in bath products. It is derived from Coconut Oil.

Cocoa Butter
A pale yellow, edible vegetable fat, obtained from the cocoa bean. It is high in unsaponifiables with a pleasant chocolate scent and flavor.

Coconut Oil
This semisolid fat obtained from the meat of the coconut is used in soap making. It contributes to hardness and lather. Sold generally at 76° F and 92° F melting points, 76° F being the most popular.

Cold Kettle Soap
See Cold Process

Cold Pressed
The process in which oils are extracted under mechanical pressure at low temperatures, typically less than 125° F. This preserves the inherent benefits and properties of the oils. 

Cold Processed Soap
Considered the most natural soapmaking process, in which the oils and lye are mixed at about the same temperature to what is called a Trace. Typically Soapmakers work with temperatures from 85° F to 100° F. When Lye (Sodium Hydroxide, Caustic Soda) is introduced into the heated oils, a process called saponification is started. The mixture is then poured into molds, covered and allowed to complete its natural process. This can take overnight to a couple of days. The soap will go through what is called a “gel stage” where the opaque soap will turn somewhat translucent and then turn back opaque again. The oils are converted to soap and glycerin.

After the soap is set up and is somewhat solid, it is de-molded, cut into bars and allowed to cure. This is where the soap will harden and lose its excess water, generally about two weeks to a month. Curing time depends on the formula, method of drying and the environment in which it is placed to cure.

Concrete
A thick, fragrant material that is extracted from a botanical base through solvent extraction. It contains the essential oils, fatty acids, and wax from the plant base.

Copra
The dried meat or kernel from the coconut from which Coconut Oil is derived.

Cosmeceutical
This refers to cosmetic products, claimed to have medicinal or drug-like benefits, which are applied topically. The term is not recognized by the FDA (Food and Drug Administration).

Cosmetic
Substances to enhance the beauty of the human body, apart from simple cleaning.

Cosmetic Grade
Refers to approval for use in cosmetics, such as colorants, dyes or fragrance oils which will come into direct contact with your skin.

CPHP
Crock Pot Hot Process, refers to a method of soap making, utilizing the heat from an electric crockpot during the soap making process (Hot Process Soap).

Cruelty-Free
Not tested on animals.

Curing
In soap, this is considered the aging process of soap and in which, most of the water evaporates from the soap, making it last longer and less likely to become soggy and sticky when used.

D

D & C
The prefix used to designate the approved safe for use in drugs and cosmetics, but not food. Example: D & C Red # 7.

DBHP
Double Boiler Hot Process. Hot Process Soap Making using a double boiler to apply heat during processing.

Decoction
A tea or infusion brewed from hard plant material or herbs, such as leaves, bark, or roots.

Deodorize
The process in which odorous matter or scent is removed from fat or oil.

Detergent
This is a petroleum-based surfactant other than soap; artificially made with a variety of chemicals. Detergent was developed during WWII when soap making oils were scarce.

DHHP
Direct Heat Hot Process. Hot Process Soap Making utilizing externally applied heat during processing.

Distillate Water
This is a by-product of steam distillation, known as floral water or hydrosol.

Distillation
A process for separation and purification of a liquid mixture which requires boiling of the liquid mixture. It is based on differences in vapor pressure of components of the mixture. The process involves vaporization of the more volatile component(s) and then condensation of the vapor back to a liquid.

DOS
Known as Dreaded Orange Spots, these are small dark orange spots radiating to yellow that occur on the surface of cold processed soap. The primary cause is thought to be unsaponified oils turning rancid. This is more prevalent in highly superfatted soaps.

DWCP
Discounted Water Cold Process. A method of making cold process soap, utilizing a lower percentage of water in the formula for the stronger lye solution.

E

Embeds
Used in soap molds to create varied shapes, colors, and designs such as the moon, stars, curls, circles, geometric shapes, etc. Embeds can be long lengths as in the full length of a loaf mold and when to cut into bars, shows a cross-section of the design or bits and pieces scattered throughout the loaf.

Emollients
These are substances that soften and soothe the skin. They are used to correct dryness and scaling of the skin. Examples are Cocoa Butter and Shea Butter.


Emu Oil
Refined from the fat of the Emu bird. Emu oil has been used for thousands of years by the Australian aborigines for the treatment of burns, wounds, bruises, and as a pain reliever for bone, muscle, and joint disorders. It is used in a variety of cosmetics for its skin-nourishing properties.

Emulsify
The blending of two or more, unblendable liquids. Many emulsions are oil/water emulsions, such as in lotions, butter, and mayonnaise.

Emulsifier
A substance that stabilizes an emulsion, such as a surfactant. This principle is exploited in soap to remove grease for the purpose of cleaning. Common examples include emulsifying wax, Cetearyl Alcohol, polysorbate 20, and ceteareth 20.

Emulsifying Wax
Used to bind oils with water when manufacturing lotions and creams. Emulsifying wax is created when a wax material (either a vegetable wax of some kind or a petroleum-based wax) is treated with a detergent (typically sodium dodecyl sulfate or polysorbates) to cause it to make oil and water bind together into a smooth emulsion.

Emulsion
A stabilized blend of oils and water such as a lotion or the suspension of one liquid within another liquid which normally does not mix.

Enfleurage
The process of withdrawing the aromatic essences from plants using odorless fats, which are solid at room temperature, to absorb the oils from plants. The fat is then dissolved in ethyl alcohol to separate the essence from the fat and distilled to remove the alcohol.

EO
See Essential Oil.

Epsom Salt
Hydrated magnesium sulfate. A white crystalline powder, bitter and colorless often used in bath preparations and foot soaks. Epsom Salts were originally obtained from the mineral waters found in Epsom, England.

Essential Oil
An oil is “essential” in the sense that it carries a distinctive scent, or essence, of the plant. A highly concentrated, volatile or ethereal oil (the essence of a plant) which is extracted from aromatic plants, (leaves, stems, flowers, bark, roots or grasses) most commonly through pressing or steam distillation. They are used for fragrance and flavorings. Historically known to have both medicinal and therapeutic properties.

Exfoliant
An abrasive added to slough off dead cells from the surface of the skin; such as pumice, oatmeal, ground cinnamon, cornmeal, and various, ground nutshells.

Expeller Pressed
A mechanical method for extracting oil from raw materials. The raw materials are  squeezed under high pressure in a single step. The oil is extracted from a base by crushing and pressing the material at temperatures less than 210° F (99° C).

Expression
The production method used to obtain citrus oils and fruit juices. The expressed or cold-pressed Essential Oils are obtained from the peels of the fruits. Expression yields Essential Oils which can contain a certain amount of non-volatile material. Juices are produced by expression of the fruit itself, often concentrated.

F

Fats
Consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water. Fats may be either solid or liquid at normal room temperature.

FDA Approved
Approved by the Food and Drug Administration of the United States.

FCC
Food Chemicals Codex, the industry-standard listing of food-grade ingredients; indicates materials safe for use in food and cosmetics.

FD&C
The prefix used to designate the approved use in foods, drugs, and cosmetics.

Felting
Wrapping a bar of soap in a non-woven fabric made of un-spun wool fiber which is matted together using heat and water. Felt is available at most fabric shops.

Fixative
Used to anchor or stabilize a scent or fragrance, to slow evaporation. Examples; Orris root is used in potpourri, Patchouli, and Vetiver in EO blends. Essential Oil scents may generally be classified by their notes or scent characteristics. They can be categorized as top notes, middle notes, and bottom (base) notes. The bottom notes tend to have the strongest staying power. The strong staying power of bottom notes plays an important role as a fixative.

Fixed Oils
The non-volatile oils obtained from botanicals such as Palm, Coconut, Olive, and Vegetable Oils. Also known as Base Oils.

Flash Point
It is the minimum temperature at which the liquid produces a sufficient concentration of vapor above it and forms an ignitable mixture with air. Examples:  Spearmint has a flashpoint of 155° F (68° C). It should not be sent by air. Patchouli is 210° F (99° C). Gasoline is -50° F (-65°C).

Floral Water
The condensed water produced during the steam distillation of a botanical base when making essential oils. It is used quite extensively in skin and body care products. This is also known as a Hydrosol or Hydrolat.

FO
See Fragrance Oil.

Formula
A list of ingredients in measured proportions. It can be expressed by volume, weight or percentages. The best way to write a formula is by percentage. This allows the use of any form of measurement and any total amount.

Fragrance-Free
Products that contain no added fragrance. The USA has no regulated definition for this term. Some commercial, fragrance-free or unscented products contain a masking fragrance.

Fragrance Oil
Combinations of synthetic and natural aroma chemicals blended to create scented oil for use in candles, bath products, and other aroma products. Some are blended to mimic natural Essential Oils or blends of EOs.

G

Gel Phase
An early phase of the saponification process, when the soap batter temporarily becomes a  warm transparent gel and slowly returns to being opaque, slightly more sold, and cooler. Not all soap batches and all soap batters go through a gel phase. 

Germaben II
An oil and water-soluble, anti-microbial preservative used in personal care products and cosmetics to inhibit the growth of yeast and mold.

Glycerin
An emollient that exists naturally in vegetable and animal fats and is present as a by-product of saponification. Glycerin is hygroscopic (absorbs water from the air) and softens the skin by helping it attract and retain moisture.

Glyceryl Stearate
An emulsifier and by-product of the soap making process.

Glycol Monostearate
An emulsifier.

Goat Milk
Goat’s Milk has long been recognized as a rejuvenator of the skin, acting as a natural moisturizer.

Goat Milk Soap
Cold Processed Soap that is made with goat’s milk. The goat’s milk can be fresh, previously frozen, or powdered goat’s milk.

Grapefruit Seed Extract
Derived from the seeds and pulp, thought to have antibiotic, antioxidant, and antiseptic properties it is used as a preservative in handmade toiletries.

GSE
Grapefruit Seed Extract

H

Hand Milled Soap
Soap made from rebatching Cold Processed Soap.

Handcrafted Soap
Often used to refer to handmade soap, this soap is crafted from a ready-made soap base using the melt and pour process.

Handmade Soap
Soap fashioned by combining a base oil with an alkali using a variety of traditional methods including hot and cold processing.

Hemp Seed Oil
Pressed from viable or sterilized seeds of the hemp plant. Contributing moisturizing properties to soaps and cosmetics; hemp seed oil is high in essential fatty acids that are easily absorbed by the skin.

Herb
A plant having aromatic qualities. Used as a seasoning and in medicine, it does not produce woody tissue and usually dies back at the end of the growing season.

Hot Process Soap Making
The soap (Oils and Lye) are heated and forced through the saponification process by cooking for several hours until the saponification is complete. The soap is then put into molds to finish setting up. Hot Process (HP) does not have the same texture and look as Cold Process. For more information on HP in production see our Q & A page.

Humectant
A substance that draws and holds moisture unto itself, for instance, glycerin.

Hydrogenation
Using hydrogen, this is a chemical process of converting vegetable oil from a liquid into a solid.

Hydrolat
See Hydrosol

Hydrosol
The condensate water produced during the steam distillation of botanical bases when making Essential Oils. Used in skin care preparations and bath products. Also known as Hydrolat or Floral Water.

Hygroscopic
The tendency of a material to absorb moisture from air. Lye and Citric Acid both have hygroscopic properties. One way to prevent this is to use desiccants packets, place in airtight containers and remove all air, etc.

Hypoallergenic
Little likelihood of causing an allergic reaction

I

INCI Name
International Nomenclature of Cosmetic Ingredients. The INCI name is a requirement when labeling cosmetics marketed in the USA.

Infusion
A product made by steeping botanicals in oil or water.

Insoluble
Not capable of being dissolved in a liquid, such as water or alcohol.

Irritant
Something that causes irritation or inflammation of the skin.

Isopropyl Mysristate
Used as an emollient to reduce greasiness.

J

Jojoba Oil
Liquid wax expressed from the seeds. Jojoba Oil is often used in skincare preparations.

K

Karite Butter
See Shea Butter

Kokum Butter
Extracted from the fruit kernels of the Garcinia Indica Tree, native to India, it is used in medicines and cosmetics. Also, know as Goa Butter. 

KOH
Potassium Hydroxide

Kukui Nut Oil
Valued as an emollient and often used in skincare products to treat dry skin. Also known as Candle Nut Oil. It is obtained from the fruit of the tree. Hawaiians have used Kukui Nut Oil for generations to treat dry skin.

L

Lanolin
Also called wool fat, wool grease or wool wax this fatty substance is obtained from wool and used in soaps and cosmetics as a moisturizer.

Lard
The semi-solid or solid fat rendered from a hog commonly used in soap making.

Lauric Acid
Dodecanoic Acid. A saturated fatty acid. It is the main acid in Coconut Oil and in Palm Kernel Oil and is believed to have antimicrobial properties.

Layering 
The process of pouring multiple layers of soap, usually of varying colors and sometimes scents.

Loofa
Also spelled, loofah or luffa. The dried fibrous section of the fruit from the plant (Luffa aegyptiaca) is often used as an exfoliating sponge. 

Lye
Known as Sodium Hydroxide. See Sodium Hydroxide.

Lye Discount
To withhold a certain percentage of Lye from a soap formula. After determining the amount of lye needed to completely saponify the fats in a recipe, only a percentage of the lye is actually used. For example; if a 6% Lye discount is called for, the amount of Lye is calculated to completely saponify the oils and or fats, then only 94% of the calculated amount of lye is actually used; 6% is withheld.

M

Macadamia Nut Oil
Expressed from the nut of the tree.  Also known as Queensland Nut Oil. Used as an emollient in soaps and cosmetics as well as a fragrance fixative.

Mango Butter
Expeller pressed and refined from the fruit kernels. Used as a base ingredient or as an added emollient in cosmetics.

Melt & Pour Soap
Also known as M&P. This is a method of handcrafting soap by melting a ready-made soap base, often adding fragrances and shaping using molds.

Melting Point
The temperature at which a solid becomes a liquid.

Mica Powders
Used in soap making to give a sheen to the soap; available in a wide spectrum of colors.

Milling
A process during commercial manufacturing where the soap is blended with fragrance, colorants and other ingredients using mechanical rollers.

Mineral Oil
A refined synthetic petroleum-based oil. Mineral Oil is widely used in commercial cosmetics. It creates a barrier and interferes with the skins normal functions. This is a poor choice for skincare preparations.


MSDS
Material Safety Data Sheet. These are information sheets provided by the manufacturer or distributor to define the health, safety and fire risks associated with products that are considered hazardous.

N

NaOH
Sodium Hydroxide.

Natural Soap
Soap that is produced from natural ingredients, free from petroleum, chemical or other artificial ingredients.

Natural Source
Obtained or derived from a natural source such as that from a botanical base.

Neem Oil
Most often used in skincare preparations for its antiseptic properties. Neem Oil is also used in insect repellents.

O

OHP
Oven Hot Process; Hot Process Soap Making using an oven to apply heat during processing

Olfactory
Of or relating to the sense of smell.

Olive Oil
Obtained from the fruit of the tree through pressing and solvent extraction. There varying grades of olive oil available. Olive Oil is often used in soap making since it does not interfere with the skins normal functions.

P

Palm Kernel Oil
Obtained from the kernels of the oil palm.

pH
Scale to measure the acidity or alkalinity of a chemical typically dissolved in water. The measurement scale goes from 0 (very acidic) to 14 (very alkaline or very basic), with pH of 7 representing neutral. Lye, a corrosive chemical used to make natural soap, has a pH of 14. Water, also used to make soap, normally has a pH of 7 and cured soap will generally have a pH between 8.5 and 10. (Note: there are many opinions on the pH of soap and what it should be. Always best to do your own research and make your own assumptions.) See article by Ann Perius-Parker: http://www.millersoap.com/phtome.html

Palm Oil
Obtained from the pulp of the fruit from the oil palm.

Paraffin
Derived from petroleum. A solid wax used in candles and cosmetics.

Peanut Oil
Rich in Vitamin E and easily absorbed into the skin, peanut oil is obtained from pressing shelled peanut kernels. 

Potassium Hydroxide
(KOH) is sometimes known as caustic potash, potassa, potash lye, and potassium hydrate. White in color, it is used in the manufacturing of soft or liquid soaps.

Propylene Glycol
Used as a moisturizer in cosmetics and a carrier in fragrance oils, also used to clarify soap.

Propylparaben
Occurs naturally in plants, it is generally made synthetically when used in water-based cosmetics.

Pumice
Light and porous lava. Used in solid and powdered form as an abrasive.

Q

R

RBD
Refined, Bleached, Deodorized.

Rebatching
Also known as hand milling, this is the process of liquefying pre-made Cold Processed Soap, adding fragrance and molding. Also known as hand milling.

Recipe
A list of ingredients in exact quantities with directions for preparing and making soap or other skincare products. This is also called a formula or formulation.


Refined
The process of purification; removing impurities from the natural or crude base.
 
Rendering
The process of melting down lard or tallow to a liquid state in order to remove solids or impurities.

Rosemary Oil Extract
Rosemary Oleoresin. This is an anti-oxidant often used as a preservative in personal care products.

S

SAP Value
See Saponification Value.

Saponaceous
Exhibits the characteristics of, or resembling the qualities of soap.

Saponification
The process or reaction of combing a base (fat) with an alkali, (sodium hydroxide) to produce a salt (soap) and free alcohol (glycerin).

Saponification Value (SAP)
The SAP Value of oil is equivalent to the amount of potassium hydroxide needed to saponify one gram of that oil.

Sea Salt
Salt obtained by the evaporation of seawater either by solar or kiln drying.

Seize 
The unforeseen thickening and uneven hardening of the soap mixture during processing. Often this is caused when adding synthetic fragrance oils to the mixture.

Separation
A term to describe trouble signs in the soap making process when the oils separate from the lye mix.

Shea Butter
A pale, solid fat from the seeds of the Shea tree, Shea Butter is used as a base ingredient or as an emollient in handmade soaps and skin preparations. Having a high content of unsaponifiables which contribute to its moisturizing properties.

Soap
Soap is a surfactant used in conjunction with water for washing and cleaning that is available in solid bars and in the form of a viscous liquid.
Chemically, soap is a salt of a fatty acid.
Traditionally, soap is made by the reaction between a fat and a strong alkali such as lye (sodium hydroxide), potash (potassium hydroxide), or soda ash (sodium carbonate).
Historically, the alkali was leached from hardwood ashes.
The chemical reaction that yields soap is known as saponification. In the saponification of fat to form soap the alkali and water hydrolyze the fat thus converting it into free glycerol/glycerin and soap (fatty acid salt). Occasionally, saponification can occur naturally.
The most common soap making process today is the Cold Process method, where fats such as vegetable oils, Palm, Olive, Coconut, Soybean, Lard, Tallow, etc. react with Lye.
Soap makers sometimes use the melt and pour process, where a premade soap base is melted and poured in individual molds. While some people think that this is not really soap making, the Hand Crafted Soap Makers Guild does recognize this as a legitimate form of soap crafting. Some Soapers also practice other processes, such as Hot Process, clear or transparent soap, which must be made with ethanol or isopropyl alcohol.
Handmade soap differs from industrial soap in that whole oils containing intact triglycerides are used and glycerin is a desirable byproduct.
Industrial detergent manufacturers commonly use fatty acids, which are detached from the glycerol heads found in triglycerides. Without the glycerol heads, the detached fatty acids do not yield glycerin as a byproduct.
Most commercial bar soaps are made from recycled and reprocessed vegetable oils gathered from restaurant grease traps, fryers, rendered animal fats, etc. These oils have to be cleaned, filtered of contaminates and sanitized. The oils are generally overcooked and valueless, except to make a cleaning agent. Fragrance oils are used to cover any off-color scent.

Soap Casting
The art of making handcrafted soaps using melt and pour soap base.

Sodium bicarbonate
Also called Baking Soda. White crystalline powder that is slightly alkaline, used in bath preparations as a water softener.

Sodium Cocoate
Saponified Coconut Oil, the sodium salt of Coconut Oil.


Sodium Hydroxide
Is a corrosive alkaline substance also known as Lye, NaOH, and Caustic Soda. Previously, Lye was among the many different alkalis leached from hardwood ashes. Solid dry Lye is commonly available as flakes, pellets, microbeads, and coarse powder. It is also available as a solution, often dissolved in water. Lye is valued for its use in food preparation, soap making, biodiesel production, and household uses, such as oven cleaner and drain opener.

Sodium Laureth Sulfate (SLES)
Emulsifier and foamer.

Sodium Palmate
Saponified Palm Oil, the sodium salt of palm oil.

Sodium Stearate
Saponified stearic acid, the sodium salt of stearic acid.

Sodium Tallowate
Saponified tallow, the sodium salt of tallow.

Solar Sea Salts
Sea Salt derived from sun evaporated seawater. It is not mined or mechanically processed. This method preserves the natural mineral content.

Soluble
Dissolvable in liquid, as in water, oil or alcohol soluble.

Solvent Extraction
A method of separating oils from their base using another liquid in which the oil is soluble. The oil is then distilled and the solvent is evaporated leaving the oil.

Soybean Oil
The oil obtained from soybeans. This is the primary ingredient in vegetable shortening.

Specific Gravity
The relative density with respect to water. This is the ratio of the weight of a given volume of a substance in relation to the weight of the identical volume of water.

Steam Distillation
A separation process in which Essential Oils are extracted from plant materials using steam and pressure. The volatile oils are separated from the hydrosol following condensation.

Stearic Acid
A fatty acid obtained from animal and vegetable fats. Commonly used in soaps, candles, and other cosmetic products.

Sunflower Seed Oil
Obtained from the seeds, sunflower oil contains vitamin E and is used as an emollient.

Superfatted 
The addition of extra oils or butter that remain unsaponified within the finished soap. These excess oils and butter contribute to the moisturizing properties of the soap.

Surfactants
Are wetting agents that lower the surface tension of a liquid, allowing easier spreading, and lower the interfacial tension between two liquids.

Synthetic
Something that is artificially produced and not of natural origin.

T

Tallow
The solid rendered suet or fat from animals such as sheep or cows. This is primarily used in soap, candles, and lubricants.

Titer
The temperature at which fatty acids solidify.

Tocopherol
Any of the four forms (alpha-, beta-, delta-, gamma-) of Vitamin E, Alpha-tocopherol having the greatest amount of Vitamin E. An antioxidant often added to soaps and lotions as an emollient due to its moisturizing properties. 

Trace
A stage in soap making where the mixture reaches a certain consistency or thickness that is most noticeable when the soap is drizzled upon itself and leaves a trail before disappearing back into the mixture.

Turbinado Sugar
Also known as Demerara Sugar, this is unrefined, raw cane sugar It is used in sugar scrubs and body polishes.

Turkey Red Oil
Also known as Sulfonated Castor Oil. It is the only oil that completely disperses in water. It is made by adding sulfuric acid to pure Castor Oil. This allows easy use for making bath oil products.

U

Unrefined
The natural unaltered base, such as the oil obtained from the first pressing.

Unsaponifiables
Components that remain in their original state and do not react with Sodium Hydroxide during saponification. These components are beneficial to a soap formula due to their moisturizing or other skin-nourishing properties.

Unscented
Products that contain no added fragrance. See Fragrance Free.

V

Vegetable Shortening
A solid fat made from vegetable oils, usually soybean oil. The oils are converted to a solid-state through hydrogenation.

Viscosity
The property of resistance to flow in a liquid or semi-liquid.

Volatile Oils
Oils that evaporate or vaporize readily at room temperatures such as Essential Oils.

W

Water -Soluble
Susceptible to being dissolved in water.

Wildcrafted
This refers to herbs and botanicals grown and harvested in the wild without the use of pesticides or other chemicals.

X

Xanathan Gum
A derivative of corn sugar used as a thickening agent in cosmetics and foods.