Glossary of Soap-Related Terms 

Acid Value
(fatty acids) The number of milligrams of KOH (potassium hydroxide) needed to neutralize the free fatty acid in 1 gram of fat or oil.
(Acidic) A solution which has a pH less than 7. See also pH.
Any ingredient added to soap that is not part of the soap molecule itself. Therefore, lye, water, and saponified oils/fats/butters are not considered additives. Examples of additives are color additives, fragrance, herbs, alcohol, silicon dioxide.
(Alkaline) A solution which has a pH greater than 7. Alkali is a synonym for base. See also pH.
Allergic Reaction
Hypersensitive response to a specific substance, called an allergen, which can be contacted through the skin, inhaled into the lungs, swallowed, or injected. The body's reaction to an allergen can be mild, such as a localized rash, or life threatening, such as anaphylactic shock.
(Basic) A solution which has a pH greater than 7. Base is a synonym for alkali. See also pH.
Base Note
See Notes
Batch Code
(Good Manufacturing Practices) A alpha-numeric code number associated with the manufacture of a specific batch of product.
Batch Record
(Good Manufacturing Practices) A record of pertinent information regarding the manufacture of a specific of batch of product, specified by its Batch Code. The record lists the manufacturing company, date made, ingredients with their sources and amounts used, their lot or batch numbers, and the signature or initials of the person verifying the product(s), measurements, temperatures, etc. It may also record any variations from normal soap making procedures, cure date, "do not use before" date, expiration date, and any additional comments.
The wax secreted by bees to make honeycombs. It is considered a natural product. It varies in color from white to yellow, is a waxy solid at room temperature, and has a melting point of 144 to 147°F (62 to 64°C).
Used as an additive in soap to make a harder bar. In Melt and Pour soap it may cause cloudiness in the soap and affect lather, depending upon the amount and soap base being used.
Best If Used by Date
(Good Manufacturing Practices) The date by which a product or ingredient should be used before it is considered unusable due to quality issues
In Melt and Pour soap bases, one condition that may happen after this date is that the MP soap base loses enough water to become dehydrated and will not work well.
(MP) The white crystal like substance that forms on the top of MP soap due to water loss (dehydration) of the soap. In MP soap, it is commonly caused by soap melted in the microwave or left out unwrapped.
The corrosive effect of a chemical on another material or living tissue. Caustic can refer to an acid or a base but is typically used to describe the action of a base.
Cold Process Method
(Abbreviated: CP) Soap making method where the starting ingredients of lye solution and a blend of oils/fats/butters are separately brought to their desired temperatures, mixed together, and allowed to react without additional heat.
Color Additives
Any ingredient which when added to a product causes the product to change color. The European Union, Canada, and United States regulate the type of color additives which may be used in cosmetics, and also regulate the specific area(s) of the body to which a color additive may be applied.
If an ingredient is added to a cosmetic for a specific functional or application purpose, and it happens to color the cosmetic, it is still considered color additive unless the color imparted is "clearly unimportant insofar as the appearance, value, marketability or consumer acceptability is concerned." [Quoted from US federal regulation 21CFR70.3(g)]
Color Fastness
The ability of a color additive to not bleed, not fade in light, and not transfer its color to lather or articles.
Color Migration
(Melt & Pour soap) The movement of color boundaries in a finished bar of soap. This occurs when using one or more water soluble color additive(s). The colored sections "bleed" or "migrate" into the section or part next to it which reduces the definition of colored boundaries.
Complaint File
(Good Manufacturing Practices) A record of a customer's complaint explaining the nature of the complaint, date of the complaint, and the action taken by the manufacturer.
To make impure or unclean by contact or mixture.
UNITED STATES: See also soap. A cosmetic is defined as:
(a) Articles intended to be rubbed, poured, sprinkled, or sprayed on, introduced into, or otherwise applied to the human body or any part thereof for cleansing, beautifying, promoting attractiveness, or altering the appearance, and
(b) Articles intended for use as a component of any such articles; except that such term shall not include soap. [Food, Drug, and Cosmetic (FD&C) Act, Sec. 201(j)]
CANADA: Cosmetics include any substance or mixture of substances manufactured, sold, or represented for use in cleansing, improving or altering the skin, hair or teeth and includes deodorants and perfumes. In Canada, soap is considered a cosmetic. [Canadian Cosmetic, Toiletry and Fragrance Association; Advertising Standards Canada; Health Canada June 1998 Revised June 2003]
EUROPEAN UNION (EU): A cosmetic product is any substance or preparation intended to be placed in contact with the various external parts of the human body or with the teeth and the mucous membranes of the oral cavity, with a view exclusively or mainly to cleaning them, perfuming them, changing their appearance, and/or correcting body odours, and/or protecting them or keeping them in good condition. In the EU, soap is considered a cosmetic. [Directive 76/768/EEC]
Cosmetic Ingredient Dictionary
A book published, usually annually, by the Personal Care Products Council. It contains the assigned INCI name for cosmetic ingredients and materials, as well as monographs for ingredients, lists of manufactures and a cross-reference from trade names to INCI names.
Excessive loss of water. In Melt and Pour soap base, dehydration may compromise the useability of the product.
Dermal Irritant
A substance that causes skin irritation when it comes in direct contact with skin. Such irritation can be an immune response (such as an allergic reaction to latex) or a direct toxic effect (such as contact with some fragrance and essential oils, herbs, spices, etc.)
Embed Material
Items that are added to soap for aesthetic purposes, such as colored or shaped pieces of soap, toys or other materials.
Embed Soap
A soap that has embed material suspended in it. This type of soap is frequently used with clear Melt and Pour soap base to showcase a design or object, or to make colored designs in opaque soap.
An agent that softens or soothes the skin.
Essential Oils
(Abbreviated EO) Undiluted volatile oils extracted from plant matter by distillation (steam or water), expression, or solvent extraction.
When a substance gives off heat, often due to a chemical reaction.
Fatty Acid
A molecule that has a saturated or unsaturated carbon chain, typically of 4 to 28 carbons, with a carboxylic acid group at one end. When a triglyceride is reacted with lye (sodium hydroxide), the fatty acids are released from the glycerin backbone, combine with the sodium hydroxide and form the sodium salt of the fatty acid. Examples:
Lauric Acid: A fatty acid with a saturated carbon chain of 12 carbons. Found in coconut oil.
Stearic Acid: A fatty acid with a saturated carbon chain of 18 carbons. Found in palm oil and lard.
Oleic Acid: A fatty acid with an unsaturated carbon chain of 18 carbons and 1 double bond. Found in palm oil
Linoleic Acid: A fatty acid with an unsaturated carbon chain of 18 carbons and 2 double bonds.
Ricinoleic Acid: A fatty acid with an unsaturated carbon chain of 18 carbons and 1 double bond, and a hydroxyl group on the twelfth carbon of the chain. Found in castor oil.
FD&C and D&C Dyes
Dyes which have been approved by the FDA for use in food, drugs, and cosmetics (FD&C) or use in drugs and cosmetics (D&C). Dyes are typically soluble in water and produce a very vibrant color. They are generally not UV-stable (colorfast) and will fade over time without the use of a color stabilizer.
In MP clear soap base, these dyes stay clear. However the colors will migrate in a multicolored MP soap as both the dye and soap are water soluble.
In hot or cold process soaps, some dyes react with the alkalinity of the soap which can alter the final color. Many blue dyes will turn to pink in cold or hot process soap.
Foul or dirty matter. An unwanted or undesired mixture of dust, soil, and other solids, such as on floors or carpets.
Flash Point
The lowest temperature at which the vapors of a liquid in air, ignite in the presence of an ignition source.
Fragrance Burn-off
When the intensity of the fragrance is reduced because the fragrance evaporates due high temperatures. This can happen when the fragrance is added to MP soap that is too hot or to cold/hot process soap that reaches high tempertures during the saponification process.
Fragrance Oils (FO)
Also known as aroma oils or aromatic oils. These oils are blends of synthetic, plant-based or "nature identical" aroma chemicals. combined to produce a particular scent. They may be diluted with a carrier like propylene glycol, vegetable oil, or mineral oil.
Gel Phase
A phase of saponification during which the cold or hot process soap temporarily becomes transparent gel. It is caused by the temperature and consistency of the soap. Not all ot all batches go through gel phase.
Glycerin Dew
(Melt and Pour soap) The appearance of clear beads of liquid on the surface Melt and pour soap soap when exposed to air. Though unsightly, it has no effect on the quality or usefulness of the soap. Wrapping finished soaps with shrink or plastic wrap to create a barrier between the soap and air prevents this problem.
Also known as glycerol and glycerine. The glycerine molecule is three carbons long, with a hydroxyl group attached to each carbon. It is extracted through the saponification of triglycerides, which releases the glycerin molecule. It is a clear,viscous liquid at room temperature which tastes sweet.
Glycerin is used as an additive to make transparent soap and is typically present in MP soap base to improve its clarity. Glycerin acts as a humectant and is often used in cosmetics for that purpose. It is also used in foods and drugs.
Gross Weight
Total weight of the container and contents.
Hot Process Method
(Abbreviated: HP) Soap making method where the soap is made as in cold process method, but then further cooked using additional heat.
Substances that absorb moisture or help another substance retain moisture.
Hydrogenated Oil
An oil that has had its unsaturated fatty acids changed to saturated fatty acids by reacting the oil with hydrogen and converting the double bonds to single bonds.
The tendency for a material to draw moisture from the air. For example, sodium hydroxide is hydroscopic and should be kept in airtight containers.
Acronym for International Nomenclature for Cosmetic Ingredients. This naming system, started by American Cosmetic, Toiletries, and Fragrance Association (CTFA), was initially used in the United States to standardize ingredient names for labeling purposes that the public would recognize. Since then, the European Union and Canada have adopted INCI nomenclature for their cosmetic ingredient labeling and in some cases, have applied their own naming conventions. Thus, the INCI name for a specific cosmetic in the United States may be different from the INCI name in Canada or in the European Union.
INCI names for specific products are assigned by the International Nomenclature Committee, sponsored by the Personal Care Products Council (the new name of the CTFA). In order to get an INCI name assigned, the manufacturer must submit an application with the appropriate fee to the International Nomenclature Committee for review.
INCI names for cosmetic ingredients and materials are published in the Cosmetic Ingredient Dictionary and Handbook, available from the Personal Care Products Council.
Iodine Value
The measure of unsaturation (referring to presence of double bonds) in a fat or oil.
An oil dispersible combination of dyes and insoluble material that is man made.
In MP soap base, they produce a very bright color that remains colorfast Lakes migrate in multilayered MP soap and are best used in single color soap pours.
Low Sweat MP Soap Base
A MP soap base, either clear or opaque, which does not form as much glycerin dew as standard MP soap bases. Low sweat MP soap base is manufactured with less glycerin than standard MP soap bases.
A solution of sodium hydroxide or potassium hydroxide dissolved in water
Soapmakers may use the term "lye" for sodium hydroxide/potassium hydroxide in it's solid state, however this is not scientifically accurate.
Material Safety Data Sheet
(Abbreviated: MSDS) A document which contains pertinent safety information about a product, ingredient or material. Generally it contains: Manufacturer or vendor information, chemical composition, hazards and potential health effects, first aid measures, fire fighting measures, spill measures, handling and storage, exposure and protection, physical and chemical properties, stability and reactivity, toxicological information, environmental information, disposal considerations, transportation information, and regulatory information.
Melt and Pour Method
(Abbreviated: MP) A soapmaking method where the soap base is commercially produced and the saponification process is complete. This pre-made soap base is formulated to withstand remelting so that the soap sets up immediately with no curing or drying time.
Melt Point
The temperature at which a solid becomes fully liquid.
A quartz-like mineral that sparkles due to optical reflection. The reflection can vary from a bright sparkle to a fine pearl depending upon the particle size. Colored micas are produced by coating mica with various dyes and pigments.
In soapmaking, the light reflection is best viewed in transparent soaps. In opaque soap, the mica tends to provide only a dull color. If dyes have been used to color the mica, the color may migrate in MP soap.
Minute, simple, single-celled forms of life which are the cause of many infectious diseases.
Middle Note
See Notes
The containers into which soap is poured. When hardened, the soap take on the shape of the mold into which it was poured. Molds may be made out of a variety of substances, depending on the type of soap being made and the intended life-span of the mold. For example, an empty milk carton may be used as a one-time mold, whereas a silicone liner in a wood mold may last for many years.
Molds come in various shapes and sizes.
Loaf mold: A long, deep three-sided mold, open on the top, to cast soap for slicing.
Log Mold: A long, three-sided mold, open on the top, large enough to slice length-wise to produce several loaves for slicing.
Vertical Log mold: A A tall mold, the size of a single bar, which is poured from the top and then unmolded into a loaf to be sliced into individual bars.
Slab mold: A shallow mold,the depth of one bar of soap. It is designed to be cut crosswise and lengthwise to product individual soaps.
Tray mold: A single cavity mold that is meant to be cut into multiple full-size bars of soap. It is similar to a slab mold.
Single mold: A single cavity, which when filled produces a single bar of soap. Single molds may be simple squares or circles or may have intricate designs.
Sheet mold: A mold that has multiple cavities on one sheet, each producing on bar of soap.
3-D Mold: A 3-dimensional mold into which soap is poured to produce a three dimensional shaped soap.
Mold Pitting
A rough texture that develops on the interior surface of a molded plastic cavity due to the use of excessive fragrance or essential oil in the soap.
MP Soap Base
(MP) A man made soap specifically formulated to be heated, melted, and solidified without changing the soap base's original properties. MP soap base is water soluble and has a pH range of 8 to 10.
See Material Safety Data Sheet
Net Weight
Weight of the contents in a container, not counting the weight of the container or lid.
Nonconforming Product
(Good Manufacturing Practices) A product in which one or more characteristics fails to meet specified requirements, deviates from quality requirements, or fails to conform to required standards.
Notes (fragrance)
The order of volatile release of a fragrance into the air. Using the analogy to a musical chord, there are top, middle, and bottom fragrant notes that harmonize to create an accord.
Top or head notes are the most volatile molecules of the fragrance that evaporate quickly and are the ones typically noticed first. They are usually light, refreshing scents that don't linger after they have been released to the air.
Middle or heart notes are the scents that are noticed after the top notes are gone. These scents form the main theme, or heart, of the fragrance.
Base notes are the scents from molecules that volatilize very slowly over a period of hours. By their nature, they provide a rich and deep lingering scent, forming the base of the perfume.
Order of Predominance
The listing of items in decreasing order based on the amount present. In the ingredient declaration for cosmetics, ingredients are listed with the ingredient present in the highest percentage first, then the ingredient with the next highest percentage, and so on.
The use of this term is regulated in many countries as it signifies that the producers follow certain business and production standards and are certified by the governing body.
(A secondary mass of soap that surrounds embed materials or embed soap.
The acidity or basicity of a chemical typically dissolved in water. The measurement scale goes from 0 (strongly acidic) to 14 (strongly basic) with pH of 7 representing neutral condition. Alkaline solutions have pH values higher than 7.0, and acidic solutions have pH values lower than 7.0. Water has a neutral pH of 7.
A substance that causes skin to become hypersensitive in the presence of radiant energy and especially sunlight. Some substances which are photo-sensitizers are citrus oil and St. John's Wort oil.
A dry, insoluble colorant, usually as a fine powder, which is used to impart color. The most common pigments approved for use in cosmetic are iron oxides, ultramarines, and titanium dioxide. Cosmetic grade pigments are required by FDA to be man made (although they have the same chemical composition and thus are "nature identical."
Pigments color soap by becoming suspended in the liquid soap and then being locked into place when the soap hardens. When added to liquid soap, the pigment should be well dispersed in a carrier liquid before being added, otherwise pigment particles may settle out, float to the surface, or clump.
In soap, pigments do not migrate and remain colorfast. Many pigments, though not all, are opaque and can cloud clear MP soap. Titanium dioxide is the industry's most commonly used pigment to make MP soap base an opaque white.
Pouring Temperature
(MP) The temperature to pour melted MP soap into the mold.
Quality Assurance
(Good Manufacturing Practices) A set of activities or techniques whose purpose is to ensure that all quality requirements are being met. In order to achieve this purpose, processes are monitored and performance problems are solved.
Quality Requirement
(Good Manufacturing Practices) A characteristic that a product must have. For example, quality requirements of soap could be defined as a soap that is free of excess alkali, has a stable shelf life, lathers and cleans adequately.
A written document which provides measurements for each ingredient and any necessary directions to correctly make the product. The measurements are typically given as percentages of the total weight of the batch or weight of each ingredient for a given batch size.
Saponification Value
Also SAP Value. The number of milligrams of KOH (potassium hydroxide) needed to saponify 1 gram of fat or oil.
If sodium hydroxide is used in a recipe rather than potassium hydroxide, the SAP Value is multiplied by a conversion factor of 0.713, which is the ratio of NaOH molecular weight to KOH molecular weight.
Saturated Fatty Acid
A fatty acid that has only single bonds connecting carbons to each other in its carbon chain.
The point in the saponification reaction when the mixture quickly becomes very thick and prevents it from being poured.
Common definition: A substance, solid or liquid, used with water to make suds and clean things.
Legal definition (US): A substance which (a) The bulk of the nonvolatile matter in the product consists of an alkali salt of fatty acids and the detergent properties of the article are due to the alkali-fatty acid compounds; and (b) The product is labeled, sold, and represented only as soap. [21 CFR 701.20]
Not all soap by the common definition meets the legal defintion. For example, many liquid hand soaps and even bar soaps are made with cleaning compounds (detergents) which are not the alkali salts of fatty acids. Soaps which meet the legal chemical definition (alkali salt of fatty acids) but claim to do more than clean (such as moisturize or hydrate) also do not meet the legal definition of soap.
In the US, soap used on the human body which meets the legal definition of "soap" (above) is exempt from the definition of a cosmetic and the regulations governing cosmetics. However, it is still regulated by the Consumer Product Safety Commission (for safety) and the Federal Trade Commission (for labeling).
In other countries, including Canada and the EU, soap applied to the human body IS considered a cosmetic and must follow the appropriate regulations.
Sodium Hydroxide
Also referred to as lye, caustic soda, sodium hydrate, white caustic, and soda lye. Molecular formula: NaOH. Molecular weight: 40.0 g/mol. It is a corrosive chemical and strong base with a pH greater than 13 when dissolved in water. Sodium hydroxide is the INCI term for NaOH.
Sodium hydroxide is used in soapmaking to react with oils and fats to produce soap.
Sodium Laureth Sulfate
(Abbreviated: SLES) Used in soap and cosmetics as a foaming, cleansing, and emulsifying agent. It can be produced by the ethoxylation of sodium lauryl sulfate (SLS). Also known as sodium lauryl ether sulfate.
Sodium Lauryl Sulfate
(Abbreviated: SLS) Used in soap and cosmetics as a foaming, cleansing, and emulsifying agent. It can be produced by the reaction of sulphuric acid with lauryl alcohol, which may be produced from lauric acid (a fatty acid obtained from coconut or palm kernel oil).
Sodium Stearate
The sodium salt (soap) of the fatty acid stearic acid (found in palm oil and animal fats). It is used in soap and cosmetics as a cleansing and emulsifying agent.
A molecule that is 6 carbons long with 6 hydroxyl groups, one hydroxyl group attached to each carbon. It is used in MP soap base to improve clarity and also acts as a humectant.
Stearic Acid
Stearic acid is a saturated fatty acid with an 18-carbon chain. It is a white, waxy solid at room temperature which has a melting point of 157°F (69.6°C).
It may be added to all types of soap to create a harder bar. In MP soap base, it may cause cloudiness in the soap and affect lather, depending upon the amount and soap base being used.
An excess of oils/fats added to the soap batch which is over an above the amount calculated to completely saponify with the lye. After saponification, there will be excess oil in the final soap but no free lye.
Suspension Base
(MP) A MP soap base that has been formulated to suspend items in it due to the addition of silica (silicon dioxide) which thickens the soap base.
Tare Weight
Weight of an empty vessel or container. The tare weight is subtracted from the gross weight to get the net weight.
Titanium dioxide
A very white pigment used in soap and cosmetics to make a white product. In MP soap, it is used to create an opaque white soap base.
Tongue Test
A quick informal test for un-reacted lye in soap. Rub wet finger on soap and then touch finger to tongue. If a tingling, pinching, or burning sensation is felt, then the soap is not ready for use. This test is greatly dependent upon the interpretation and sensitivity of the soapmaker.
Top Note
See Notes
The point in the saponification reaction when the mixture becomes thick enough to prevent separation of the oils and lye. The term describes the activity of dragging a spoon through this thickened mixture and a "trace" is left on the mixture's surface.
A molecule that has three fatty acids attached to a backbone of glycerin. Commonly found in oils or fats, which may be solid or liquid at room temperature.
Unsaponifiable Matter
The weight percentage of an oil/fat/wax that does not react with alkali to form soap.
Unsaturated Fatty Acid
A fatty acid that has one or more double bonds connecting carbons to each other in its carbon chain. An unsaturated fatty acid that has only one double bond is known as monounsaturated. An unsaturated fatty acid that has more than one double bond is known as polyunsaturated.

NOTE: Some material in the How-To Library is limited to R Registered Users or M Members. If you Login or Register you can take advantage of more available content.