Glossary of General Soap Making Terms - The Soap Coach
Glossary of General Soap Making Terms

The soap making world seems to be full of lots of odd, sometimes long and sometimes science related words which are a bit overwhelming when you first start out with your new hobby so here is a round up of all those I can think of. If you are looking for those that are used more in the soap business space then take a look at THIS blog post.

Alkali - A compound with a PH greater than 7. Sodium Hydroxide (lye) is an alkali as is Potassium Hydroxide.

Accelerate - When a soap batter thickens up and reaches trace far quicker than expected. Normally caused by a particular essential oil or fragrance oil. See also Seize.

Allergen - A substance that can cause an allergic reaction in some individuals. Normally found in fragrances in the context of soap making.

Base -The alkali used in soap making. Sodium Hydroxide and Potassium Hydroxide are bases.

Bastille Soap - Soap which is high in olive oil, generally over 70% of the total weight of oils.

Botanicals- Any petal, powder, seed etc which is plant derived.

Caustic Potash Another name for Potassium Hydroxide. It is the alkali (base) used in liquid soap making.

Caustic Soda - Another name for Sodium Hydroxide (lye). It is the alkali (base) used in bar soap making.

Cold Process - The traditional method of soap making that only requires heat to melt oils. No additional heat is used.

Cosmetic Grade - Ingredients that are suitable for using in body products like soap, bath and body products and make-up. Generally refers to colour and fragrance in soap making.

Cold Process - Acronym for 'cold process' soap making.

CPOP - Acronym for 'cold process/oven process'. Soap is made using the cold process method but is then placed in a pre warmed oven in order to force the gel stage.

Cure - The time period between making the soap and its use. Generally 4 to 6 weeks. During this time the soap loses water and also undergoes chemical changes.

DOS - An abbreviation for Dreaded Orange Spot. Exact cause unknown. Possibly by using oils with a short shelf life or other impurities. Looks a little like rust spots.

Embeds - Smaller pieces of soap that are 'embedded' into the soap batter during the soap making process. Can be used to create pictures or just add pattern.

Emulsion -The blending of substances that are normally not mixable. In soap making when you mix your lye solution with your butters and oils you are causing them to emulsify.

Essential Oil -An oil that has been obtained from a plant. Generally by steam distillation but other methods are used depending upon the plant.

Exfoliant -An ingredient added to soap to help remove dead skin cells and dirt. Ground pumice is a good example.

Exothermic reaction -A chemical reaction between substances that releases energy, normally in the form of heat, when it occurs. When you mix your sodium hydroxide with water to generates an exothermic reaction.

Fatty Acids -The building blocks of your soap. They are compounds of carbon, oxygen and hydrogen found in fats and oils and can be saturated or unsaturated. There are several different types and each brings a different property to your soap.

Fragrance Oil - Synthetic, lab created scent.

Gel Phase -If the soap batter is kept warm after pouring into the mould it will warm up so much during the chemical reaction that it becomes translucent and gel like. Colours will generally be more vibrant if your soap reaches gel phase but it is not necessary to create a lovely bar of soap. There are some situations where you would not want gel phase - milk soap is an example as the milk may scorch.

Glycerine -A thick, sticky, clear liquid created as a result of saponification. Handmade soaps retain the glycerine. Commercial soaps often remove it as it is more valuable to them in other skincare products. Glycerine is a natural emollient and humectant and a god thing to have in your soap.

Glycerine Rivers -Silvery lines running through your soap where the glycerine pools during saponification. Harmless but often not appreciated by soap makers for aesthetic reasons.

Glycerine Soap -Transparent soaps made using a similar method to hot process soaps that also contain extra glycerine, solvents and sugar.

Heat Transfer Method -A soap making method similar to the cold process. Instead of using heat to melt hard oils, the hot lye solution is used instead. Useful for time saving but it does not work for those recipes high hard butters and oils.

Hot Process - A method of soap making that requires external heat to speed up the process of saponification. Generally but not exclusively done in a slow cooker.

HP - Acronym for 'hot process' soap making.

INCI -The International Nomenclature of Cosmetic Ingredients, abbreviated INCI, is a global system of names for waxes, oils, pigments, chemicals, and other ingredients of soaps, cosmetics, and the like. Using INCI names ensures there is no confusion over identifying ingredients in cosmetics and all labels of such products in the UK must use INCI names.

KOH -The chemical formula for Potassium Hydroxide.

Lye -Another name for Sodium Hydroxide. Should be used for the water and sodium hydroxide solution rather than Sodium Hydroxide alone.


M & P - Pre made soap that can be melted down, have fragrance and colour added and then be poured into a mould. Generally has solvents added to enable this.

Melting Point - The temperature at which a solid substance (butters and hard oils) melts.

Milled Soap - A commercial process that removes the glycerine from the soap, forms it into pellets, adds fragrance, and presses the soap into shape.

NaOH - The chemical formula for Sodium Hydroxide.

pH - pH is the measure of the acidity or alkalinity of a solution. A substance with a pH value greater than 7.0 (alkaline) are bases; less than 7.0 (acidic) are acids with 7.0 being neutral. All soaps are alkaline with a PH of between 9.5 and 10.5 generally. If it is any less than this it is not a true soap.


Potassium Hydroxide - The alkali (base) used in liquid soap making.

Re-batching - Can sometimes be used to rescue a soap that has gone wrong by grating it up, adding a small amount of liquid and applying heat until it reaches a translucent stage and then remoulding. Care should be taken as often it is hard to know how lye heavy or light a soap that has gone wrong is.

Ricing - When a fragrance oil reacts with your base oils and produces little rice shaped grains in your soap batter. The soap batter will resemble rice pudding.

SAP Value - The number of milligrams of potassium hydroxide or sodium hydroxide required to saponify 1 gram of fat. All butters and oils have different SAP values.

Saponification - Saponification is the chemical reaction between an alkali (lye) and a fat or oil to form soap.

Seize - A rapid solidifying of the soap while still in the soap pan. Usually caused by high amounts of stearic or palmitic acid (found in your butters and oils) or most commonly by some fragrance & essential oils. There is nothing you can do except get it in your mould as quickly as possible.

Soap - The end result of a chemical reaction between a lye solution (sodium hydroxide for bar soap or potassium hydroxide for liquid soap) and fats/oils/butters.

Soap Calculator - An online tool for calculating the quantity of sodium or potassium hydroxide to make soap using your chosen butters and oils.

Soda Ash - A powdery white residue (sodium carbonate) that sometimes forms on the surface of soap. It is caused by the sodium hydroxide reacting with the air before it has chance to turn into soap.

Sodium Hydroxide - The alkali (base) used in bar soap making.

Superfat - The excess oils left unsaponified in the finished soap. This excess oil contributes to the moisturising qualities of soap.Usually between 5 and 8% in most recipes.

Tongue Test - A very basic test to check for excess lye in your soap. Also known as a zap test. Not one I teach just in case!!!

Trace - The point in soap making where the mixed lye and oils have combined to a pancake like batter. Trails of the batter can be seen when dropped from your blender on to the surface . At this point you can be sure you lye and oils will not separate back out.

Unsaponifiables - The portion of oils that do not participate in the saponification process and remain in their natural state in the finished product.

Zap Test - See tongue test as above

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