Soap Making Glossary

When a soap batter thickens faster than expected, often caused by fragrance oils, high temperatures, or certain oils like castor oil. Acceleration can make it difficult to swirl or pour designs before the batter sets up.

A base note fragrance or essential oil added to help fix and extend the scent of a lighter fragrance in soap. Common anchors include patchouli, benzoin resin, and cedarwood. The anchor slows evaporation of the lighter top notes so the scent lasts longer in the finished bar.

A soap recipe that uses at least 70% olive oil, with the remaining oils making up the balance. The name plays on Castile soap (which is 100% olive oil) but with added oils for better lather and hardness.

Dried plant materials added to soap for decoration or mild exfoliation. Examples include lavender buds, calendula petals, chamomile flowers, and rose petals. Most botanicals turn brown in cold process soap over time due to the high pH. Calendula is a notable exception that retains its golden color.

The big, fluffy type of lather produced by lauric and myristic fatty acids (found in coconut oil, palm kernel oil, and babassu oil). High bubbly lather often comes with higher cleansing, which can be drying. Balancing bubbly and creamy lather creates the most satisfying bar.

A base oil used in soap making (and cosmetics) that 'carries' essential oils and other ingredients. Carrier oils provide the fatty acids that become soap. Common carrier oils include olive, coconut, palm, avocado, and sweet almond oil. Each contributes different properties to the finished bar.

Soap made with 100% olive oil. Named after the Castile region of Spain. Castile soap produces a mild, conditioning bar with a creamy (not bubbly) lather. It requires a longer cure time of 6 to 12 months for best results.

An additive that binds metal ions in water (calcium, magnesium, iron) to prevent soap scum, dreaded orange spots, and rancidity. Common chelators for soap include citric acid (1 to 2% of oil weight, with extra lye to compensate), EDTA, and sodium citrate.

A natural chelator (water softener) commonly added to soap at 1 to 2% of oil weight. It binds calcium and magnesium ions, reducing soap scum and extending bar life. Extra lye must be added to neutralize the citric acid (0.624g NaOH per 1g citric acid). The result is sodium citrate in the finished bar.

A natural mineral additive used in soap for color, gentle exfoliation, and to help anchor fragrance. Popular clays include kaolin (white, gentlest), bentonite (green-gray, absorbing), French green clay, and Moroccan red clay. Typically added at 1 to 2 teaspoons per pound of oils.

A bar property determined by the lauric and myristic acid content. Higher cleansing bars remove more oils from the skin. Recommended range is 12 to 22. Above 22, the bar may strip the skin's natural moisture barrier and feel drying. Coconut oil is the primary contributor to cleansing.

A hard, brittle butter extracted from cacao beans. Adds hardness, creaminess, and a subtle chocolate scent to soap. Rich in stearic and palmitic acids. Typically used at 5% to 15% of a recipe. Higher percentages can cause cracking and reduce lather.

One of the most common soap making oils. Produces a very hard bar with big, bubbly lather and strong cleansing. Rich in lauric and myristic acids. Typically used at 15% to 30% of a recipe. Higher percentages (above 30%) can be drying to skin unless superfat is increased. The 76-degree variety is standard for soap.

A soap making method where oils and lye solution are mixed at relatively low temperatures (around 100 to 130 degrees F). The soap is poured into molds and left to saponify on its own over 24 to 48 hours, then cured for 4 to 6 weeks.

Any substance used to add color to soap. Options include micas (shimmer), oxides and ultramarines (matte), natural clays, activated charcoal, turmeric, paprika, and lab-certified FD&C or D&C colorants. Not all colorants are stable in the high pH environment of cold process soap.

A bar property determined by oleic, linoleic, linolenic, and ricinoleic acid content. Higher conditioning bars are more moisturizing and leave skin feeling softer. Recommended range is 44 to 69. Olive oil, avocado oil, and shea butter are major contributors to conditioning.

A hybrid method where cold process soap is placed in a warm oven (around 170 degrees F, then turned off) after pouring into the mold. This forces gel phase throughout the entire bar, producing more vibrant colors and a slightly translucent appearance.

A regulatory requirement in the EU and UK for selling cosmetic products, including soap. The report assesses the safety of each ingredient and the finished product. It must be prepared by a qualified safety assessor. Required before any soap can be legally sold in these markets.

The thick, lotion-like type of lather produced by palmitic and stearic fatty acids (found in palm oil, lard, tallow, cocoa butter, and shea butter). Creamy lather is stable and feels luxurious on skin. It complements bubbly lather for a well-rounded bar.

The process of allowing finished soap to sit in open air for 4 to 6 weeks after unmolding. During curing, excess water evaporates, the bar hardens, the crystal structure matures, and the pH drops. A properly cured bar lasts longer, lathers better, and is milder on skin.

Reducing the amount of water in a recipe below the standard ratio. A 10% water discount means using 10% less water than calculated. Less water produces harder bars faster, but the batter traces more quickly, leaving less working time.

Orange or yellow spots that appear on cured soap, caused by the oxidation of unsaturated fatty acids (rancidity). DOS is more likely in recipes with high iodine values, high superfat, or when exposed to heat, light, or metals in the water. Chelators like citric acid and proper storage help prevent DOS.

The initial stage of mixing oils and lye solution where the two liquids blend together but have not yet reached trace. The mixture looks like thin, smooth liquid. Stick blending speeds emulsion significantly compared to hand stirring.

A concentrated, volatile aromatic compound extracted from plants through distillation or cold pressing. Essential oils provide natural fragrance to soap and some offer therapeutic properties. Usage rates vary by oil (typically 2% to 5% of oil weight). Some essential oils accelerate trace or discolor soap.

An ingredient added to soap for physical exfoliation. Options range from gentle (colloidal oatmeal, jojoba beads) to aggressive (pumice, walnut shell). Ground coffee, poppy seeds, and sea salt are also popular. The amount added determines how scrubby the finished bar feels.

When soap batter appears to have reached trace but has not actually emulsified. This usually happens when solid oils or butters re-solidify because the temperatures dropped too low. The batter may look thick but will separate later. Working at proper temperatures prevents false trace.

The building blocks of oils and fats that determine the soap's final properties. Each fatty acid contributes different qualities: lauric and myristic acids add cleansing and bubbly lather, palmitic and stearic acids add hardness and creamy lather, oleic acid adds conditioning, and linoleic acid adds a silky feel.

A variation of hot process soap making that uses extra water or additives like sodium lactate and yogurt to keep the cooked soap batter more fluid and pourable, resulting in smoother bars that resemble cold process soap.

The percentage of fragrance oil or essential oil relative to the total oil weight in a soap recipe. A typical fragrance load is 5% to 7% of oil weight for fragrance oils and 2% to 4% for essential oils. Exceeding the recommended usage rate can cause skin irritation or batter problems.

A synthetic or blended aromatic compound designed for use in soap and cosmetic products. Fragrance oils are typically stronger and more stable than essential oils in soap, but quality varies. Always check that a fragrance oil is rated for cold process soap, as some may accelerate, discolor, rice, or seize.

A stage during saponification where the soap heats up (reaching 140 to 180 degrees F internally) and becomes translucent and gel-like. Gel phase produces more vibrant colors and a slightly shinier bar. It can be forced (by insulating the mold) or prevented (by putting the mold in the refrigerator).

A natural humectant (moisture-attracting substance) that is a byproduct of saponification. In handmade soap, glycerin remains in the bar, contributing to its moisturizing properties. Commercial soap manufacturers often remove glycerin to sell separately, which is one reason handmade soap feels better on skin.

A swirling technique where a wire hanger or similar tool is pushed through poured layers of differently colored soap batter in the mold. The tool is moved in specific patterns (figure-eight, S-curve, zigzag) to create flowing designs throughout the bar.

Oils and fats that are solid at room temperature, such as coconut oil, palm oil, lard, tallow, cocoa butter, and shea butter. Hard oils contribute to bar hardness, longevity, and typically contain more saturated fatty acids. A good recipe usually has 40% to 60% hard oils.

A bar property determined mainly by palmitic, stearic, lauric, and myristic acid content. Harder bars last longer in the shower and unmold more easily. Recommended range is 29 to 54. Very hard bars (above 54) may crack or feel waxy. Coconut oil, palm oil, tallow, and cocoa butter increase hardness.

A soap making method where the soap batter is cooked (usually in a slow cooker or double boiler) after reaching trace. Cooking accelerates saponification so the soap is technically usable immediately, though curing for 1 to 2 weeks still improves the bar.

The essential tool for soap making. A handheld blender that quickly emulsifies oils and lye solution, bringing the batter to trace in minutes rather than the hours required by hand stirring. Use short bursts of blending alternated with stirring to control trace speed.

A swirling technique where colors are added directly to the soap pot rather than the mold. Different colored batters are layered or drizzled into the main pot, then gently stirred before pouring into the mold for a marbled effect.

International Nomenclature of Cosmetic Ingredients. The standardized naming system used on cosmetic and soap labels. For example, water is listed as Aqua, coconut oil as Cocos Nucifera Oil, and sodium hydroxide as Sodium Hydroxide. INCI names are required on product labels in most countries.

A quality indicator for soap recipes, calculated from the SAP value and iodine value of the oil blend (INS = SAP x 1000 minus Iodine Value). An INS between 136 and 170 generally indicates a well-balanced bar. It is a guideline, not an absolute rule, and should be considered alongside individual bar properties.

A measure of how unsaturated (soft) an oil or fat is. Higher iodine values indicate more unsaturated fatty acids. In soap making, a blend's iodine value above 70 suggests the bar may be soft and prone to rancidity (dreaded orange spots). Below 50 indicates a very hard bar.

The alkali used to make liquid soap. KOH reacts with oils to produce potassium salts of fatty acids, which are softer and more water-soluble than sodium soaps. KOH has a different SAP value than NaOH (approximately 1.4 times higher by weight) and the two cannot be directly substituted.

Legal requirements for selling soap vary by country. In the US, true soap (makes no cosmetic claims) is regulated by the CPSC and needs only the product name, net weight, and business name/address. Soap with cosmetic claims (moisturizing, anti-aging) falls under FDA cosmetic regulations and requires full ingredient listing in INCI order.

Rendered pig fat. Produces a mild, white bar with creamy lather and good hardness. Similar fatty acid profile to palm oil, making it a common palm-free substitute. Lard soap benefits from a longer cure time (6 to 8 weeks) and traces slowly, allowing good working time.

The common name for sodium hydroxide (NaOH) or potassium hydroxide (KOH), the alkali needed to convert oils into soap. NaOH produces solid bar soap. KOH produces liquid soap. Lye is fully consumed during saponification and no lye remains in properly made soap.

A tool that calculates the exact amount of lye and water needed for a soap recipe based on the oils used, their SAP values, and desired superfat percentage. A lye calculator is essential because each oil requires a different amount of lye. Soaply provides a free, full-featured lye calculator.

The ratio of lye to total lye solution (lye plus water), expressed as a percentage. A 33% lye concentration means the solution is 33% NaOH and 67% water. Higher concentrations produce faster trace, harder bars, and shorter unmolding times. Standard range is 28% to 33%.

Another term for superfat. It refers to using less lye than required to saponify all oils in the recipe, leaving a percentage of unsaponified oils (free oils) in the finished bar for extra moisturizing. A 5% lye discount is the same as 5% superfat.

A pre-mixed lye solution made in bulk and stored for future soap making sessions. By preparing a large batch of lye solution at a known concentration, you save time and can measure out exactly what you need for each recipe. The solution should be stored in clearly labeled, HDPE plastic containers.

A soap making method using pre-made soap base that is melted, customized with color, fragrance, and additives, and poured into molds. No lye handling is required, making it beginner-friendly. The base has already undergone saponification during manufacturing.

A mineral-based pigment that provides shimmer and color to soap. Micas are available in a wide range of colors and are popular for swirl designs. Some micas morph (change color) in cold process soap due to the high pH. Lab-tested micas labeled safe for soap are most reliable.

The container into which soap batter is poured to set. Common types include silicone loaf molds (most popular, easy release), wooden molds (lined with freezer paper or silicone), individual cavity molds (for guest-sized bars), and slab molds (for cutting into bars).

The alkali used to make solid bar soap. NaOH reacts with oils and fats in a process called saponification to produce sodium salts of fatty acids (soap) plus glycerin. Must be food-grade or technical-grade, at least 97% pure for soap making.

The backbone of many soap recipes. Produces a mild, conditioning bar with creamy (not bubbly) lather. Rich in oleic acid. Pomace grade is preferred for soap as it traces faster than extra virgin. High olive oil percentages (above 70%) require longer cure times for best results.

A common hard oil that adds hardness, longevity, and a stable creamy lather to soap. Palm oil must be fully melted and mixed before measuring to ensure even distribution of its components. Environmental concerns about palm oil production have led some soap makers to seek alternatives or use only RSPO-certified sustainable palm.

When only part of the soap bar goes through gel phase, typically the center (which retains more heat) while the edges stay cooler. This creates a visible ring or color difference between the gelled center and ungelled edges. Usually considered undesirable.

A measure of acidity or alkalinity on a scale of 0 to 14. Properly cured soap typically has a pH of 8 to 10, which is mildly alkaline. Fresh soap may have a higher pH that drops during curing. A pH above 10 may indicate excess lye. pH test strips provide a quick check, though the zap test is more reliable for lye safety.

A common unit of measurement for soap additives. Recipes often specify additives in amounts per pound of base oils. For example, '1 teaspoon sodium lactate PPO' means adding 1 teaspoon for each pound of oils in your recipe. This keeps the ratio consistent regardless of batch size.

The process of grating or chopping cured or partially cured soap, melting it down with a small amount of liquid, and remolding it. Rebatching is used to fix failed batches (wrong measurements, ugly appearance) or to add heat-sensitive ingredients like essential oils.

When soap batter develops tiny, rice-like lumps, usually caused by a fragrance oil reacting with the batter. The batter separates into a grainy or cottage cheese-like texture. Stick blending through mild ricing can sometimes save the batch.

A cold process technique where both the oils and lye solution are brought to room temperature before mixing. This gives the most working time and reduces the chance of acceleration, making it popular for intricate swirl designs.

The amount of lye required to fully saponify one gram of a specific oil or fat. Each oil has a unique SAP value. Soaply's calculator uses these values to determine exactly how much lye your recipe needs. SAP values differ for NaOH and KOH.

The chemical reaction between an alkali (lye) and fatty acids (oils/fats) that produces soap and glycerin. The reaction is exothermic (generates heat) and typically takes 24 to 48 hours to complete in cold process soap, though curing continues for weeks.

When soap batter suddenly solidifies in the pot, becoming too thick to pour or work with. Seizure is usually caused by fragrance oils (especially floral fragrances like jasmine and lily of the valley), high temperatures, or acceleration that was not caught early enough.

A soft butter from the African shea tree. Adds conditioning, creaminess, and a silky feel to soap. Rich in stearic and oleic acids. Typically used at 5% to 15% of a recipe. Higher percentages can produce a softer bar with less lather. Often contributes to a sticky feel at trace.

A tool for cutting loaf soap into even bars. Options range from a simple straight knife to multi-bar wire cutters. Most soap is cut 24 to 48 hours after pouring, when it is firm enough to hold its shape but soft enough to cut cleanly. Bar thickness is typically 1 to 1.25 inches.

A white, powdery residue (sodium carbonate) that can form on the surface of cold process soap when unsaponified lye reacts with carbon dioxide in the air. It is harmless but cosmetically unappealing. Spraying with 99% isopropyl alcohol after pouring and covering the mold can prevent it.

A salt derived from the fermentation of sugars. Added to cooled lye solution at 1 teaspoon per pound of oils, it produces a harder, smoother bar and helps with unmolding. Sodium lactate acts as a humectant in the finished soap and is especially helpful for recipes with lots of soft oils.

Oils that are liquid at room temperature, such as olive oil, sunflower oil, avocado oil, sweet almond oil, and canola oil. Soft oils contribute to conditioning, moisturizing, and a silky skin feel. Too many soft oils produce a bar that is mushy and does not last long.

The percentage of oils in a recipe that remain unsaponified in the finished soap. A 5% superfat means 5% of the total oil weight is free oil, making the bar more moisturizing. Most recipes use 3% to 8% superfat. Too high a superfat may produce greasy bars that go rancid faster.

Rendered beef fat. Produces a hard, white bar with creamy lather and excellent longevity. Rich in palmitic and stearic acids. Tallow has been used in soap making for centuries and is still valued for producing a firm bar with a smooth feel. It can be rendered at home or purchased pre-rendered.

The point during soap making when the oil and lye mixture has emulsified and thickened enough that drizzling batter across the surface leaves a visible trail before sinking back in. Light trace resembles thin cake batter. Medium trace holds a light pattern. Thick trace is like pudding.

Removing the soap from its mold, typically 24 to 72 hours after pouring. The soap should be firm enough to hold its shape. Silicone molds release easily; wooden or plastic molds may need freezing or lining with parchment. Sodium lactate added at trace helps bars unmold more easily.

Selling soap in bulk to retailers, boutiques, or other businesses at a discounted price (typically 50% of retail). Wholesale requires consistent quality, reliable supply, proper labeling, and liability insurance. Pricing must account for the 50% discount while still covering costs and profit.

A method of testing whether soap has excess lye. Touch your tongue briefly to the soap surface. If you feel a 'zap' similar to touching a 9-volt battery, there is still free lye present and the soap needs more curing time or should not be used. If it just tastes like soap (unpleasant but no zap), it is safe.