Frequently Asked Questions

SoapIndex is a free soap formulation platform that combines a precision lye calculator, an ingredient library of 316+ oils and additives, a recipe collection from soapmakers worldwide, and an AI assistant called Soapy. Whether you are a first-time soapmaker or an experienced formulator, SoapIndex gives you the chemistry data and tools to create safe, high-quality soap.

No. The soap calculator is completely free and works without an account. You only need to sign up if you want to save recipes, publish them to the community, or use features like recipe remixing. Creating an account is free and takes about 30 seconds.

Start by reading our safety guide, then pick a simple beginner recipe from the recipe library (look for "Beginner" difficulty). A classic first recipe uses olive oil, coconut oil, and palm oil (or a palm alternative like lard). Weigh your oils, prepare your lye solution, combine at the right temperature, pour into a mold, and wait 24-48 hours to unmold. Cure for 4-6 weeks before using.

At minimum you need: a digital scale accurate to 1 gram, an immersion (stick) blender, heat-resistant mixing containers (stainless steel or HDPE plastic), a silicone spatula, a thermometer, a soap mold, and safety gear (chemical splash goggles, nitrile gloves, long sleeves). See our safety guide for the full PPE checklist.

Cold process (CP) soap is poured into a mold after reaching trace and saponifies slowly over 24-48 hours, then cures for 4-6 weeks. Hot process (HP) soap is cooked (usually in a slow cooker) to force saponification to complete in a few hours, so it is usable sooner but has a more rustic, textured appearance. Both produce real soap; CP gives smoother bars and more design options.

Active hands-on time is about 1-2 hours for a cold process batch. After pouring, the soap needs 24-48 hours in the mold, then 4-6 weeks of curing time where excess water evaporates and the bar hardens. Hot process soap can be used sooner (1-2 weeks) but still benefits from curing.

Yes, when you follow proper safety procedures. Lye (sodium hydroxide) is caustic and requires respect, but millions of people make soap safely at home. Always wear goggles and gloves, work in a ventilated area, and keep children and pets away from your workspace. Read our full safety guide before your first batch.

Most beginners start with 450-700 grams (1-1.5 lbs) of oils. This produces 4-6 bars and is small enough to manage safely while being large enough to work well with a stick blender. Avoid very small batches under 300g as they are harder to blend and more sensitive to measurement errors.

Open the calculator, choose your soap type (bar or liquid), then add oils from the ingredient list by clicking them or searching by name. Enter each oil's weight or percentage, set your superfat level and water ratio, and the calculator instantly shows you the exact lye and water needed plus quality metrics and fatty acid breakdown. You can adjust in real time until you are happy with the formulation.

Superfat is the percentage of oils that remain unsaponified (not turned into soap) in your final bar. It acts as a safety margin ensuring no free lye remains, and the leftover oils add moisturizing properties. A 5% superfat is the standard starting point. Go lower (2-3%) for a harder, more cleansing bar, or higher (6-8%) for extra moisture. Above 8% increases the risk of dreaded orange spots (DOS) from rancid unsaponified oils.

They are two ways of expressing how much water to use. Water-as-percentage-of-oils (e.g., 38%) calculates water relative to your total oil weight. Lye concentration (e.g., 33%) describes what percentage of the lye solution is actual lye. A 33% lye concentration is the most common "water discount" and produces bars that unmold faster and cure more quickly. The calculator lets you switch between both methods.

The quality bars (hardness, cleansing, conditioning, bubbly, creamy, iodine, INS) have ideal ranges, but no single oil scores perfectly in all categories. A high-olive recipe will have excellent conditioning but low cleansing and bubbles. That is normal. Use the metrics as a guide to balance your recipe, not as a strict pass/fail. A well-balanced bar typically combines a hard fat (coconut, palm, or tallow), a conditioning oil (olive, avocado), and a luxury oil (castor, shea butter).

Yes. Switch the soap type to "Liquid" in the calculator and it will automatically use potassium hydroxide (KOH) SAP values instead of sodium hydroxide (NaOH). KOH requires about 40% more alkali by weight than NaOH for the same amount of oil. The calculator handles all the math for you.

INS is a calculated index that predicts overall bar quality based on the iodine value and SAP values of your oils. An ideal INS value is around 160. Below 135 tends to produce soft, easily spoiled bars; above 170 can be overly hard and brittle. It is a useful guideline but not an absolute rule — many excellent recipes fall outside the "ideal" range.

Click the "Save Recipe" button in the calculator. If you are not signed in, you will be prompted to create a free account. Saved recipes appear in your dashboard where you can edit, duplicate, or publish them. You can also share a direct link to any saved recipe.

There is no automatic import feature yet, but recreating a recipe is quick. Open the calculator, add the same oils and percentages from your existing recipe, and set the same superfat and water ratio. The SoapIndex calculator will recalculate lye amounts using its own SAP values, which may differ very slightly from other calculators. Always verify lye amounts before making a batch.

The three most common starter oils are olive oil (conditioning, gentle, widely available), coconut oil 76° (hardness, lather, cleansing), and palm oil or lard/tallow (hardness, creaminess, long-lasting bars). A classic beginner recipe is 40% olive, 30% coconut, and 30% palm. Browse the ingredient library to see each oil's properties.

Yes. Regular, light, or extra-virgin olive oil all work for soap making. Extra-virgin produces a greenish bar with a subtle earthy scent; lighter grades produce a more neutral color and smell. Pomace olive oil (the cheapest grade) is actually preferred by many soapmakers because it reaches trace faster than extra-virgin. All grades have the same SAP value.

The number refers to the melting point in Fahrenheit. Coconut oil 76° is the standard variety sold in grocery stores; it melts at about room temperature and produces excellent lather and hardness. Coconut oil 92° is hydrogenated, stays solid at higher temperatures, and produces an even harder bar. They have slightly different SAP values, so make sure to select the right one in the calculator.

Palm oil is popular because it produces a hard, long-lasting bar with a creamy lather at a low cost. However, palm oil farming has significant environmental concerns including deforestation. Common palm-free alternatives include lard, tallow, cocoa butter, mango butter, or a blend of shea butter and coconut oil. Check the ingredient library to compare properties and find substitutions that hit similar quality metrics.

Castor oil is a unique soap additive because it is high in ricinoleic acid, which acts as a humectant and produces a dense, stable, bubbly lather. Most recipes use castor oil at 3-8% of the total oils. Higher percentages can make the bar sticky and soft. It is one of the most universally recommended oils in soap formulation.

Essential oils (EOs) are steam-distilled or cold-pressed from plants and are 100% natural. Fragrance oils (FOs) are synthetic or blended compounds designed to provide specific scents. Both work in soap, but they behave differently: some EOs fade or discolor in cold process soap, while certain FOs can accelerate trace or cause seizing. Always check the supplier's recommended usage rate.

A common guideline is 3-5% of total oil weight for essential oils, which translates to roughly 15-25 grams per 500 grams of base oils. However, some essential oils (like cinnamon bark or clove) are skin sensitizers and should be used at much lower rates. Always check the IFRA guidelines for your specific essential oil and do a small test batch first.

SAP (saponification) values tell you exactly how much lye is needed to fully convert a specific oil into soap. Every oil has a unique SAP value based on its fatty acid composition. The calculator uses these values to compute the precise lye amounts for your recipe. SoapIndex maintains SAP values for all 316+ ingredients in its library, sourced from published chemical references.

Additives like clays, colorants, fragrance oils, milk, honey, and exfoliants are not oils and cannot be saponified, so they have no SAP value. They are added to soap for their specific properties (color, scent, texture, skin benefits) but do not participate in the lye reaction. The calculator only needs SAP values for the base oils and butters.

Yes, all three are popular soap additives. Honey adds a golden color, gentle sweetness, and extra lather. Milk (cow, goat, coconut, oat) replaces some or all of the water and produces a creamier, more moisturizing bar. Beer adds sugars for lather. With all three, you must soap at lower temperatures (room temperature lye solution) because the sugars can overheat and scorch. Freeze milk or beer before mixing with lye.

Lye (sodium hydroxide and potassium hydroxide) is a strong caustic alkali that can cause serious chemical burns on contact with skin or eyes. However, it is perfectly safe to work with when you wear proper protective equipment (goggles, gloves, long sleeves), work in a ventilated area, and follow standard procedures. Every bar of handmade soap requires lye — there is no way around it. Read our full safety guide before handling lye for the first time.

Immediately flush the affected area with cool running water for at least 15 minutes. Remove any contaminated clothing. Do not use vinegar or other acids — the neutralization reaction generates heat and can make the burn worse. If irritation persists or the exposure is large, seek medical attention. For eye contact, flush with water for 15 minutes and seek medical help immediately.

No. Saponification — the chemical reaction that creates soap — requires an alkali (lye). Every real soap, including commercial bars, was made with lye. The good news is that no lye remains in properly formulated finished soap; it is entirely consumed in the reaction. If you want to skip handling lye, you can use a pre-made melt-and-pour soap base, but that is not true from-scratch soap making.

In the US, food-grade or technical-grade sodium hydroxide is available from soap making suppliers (Bramble Berry, Nurture Soap, Bulk Apothecary), Amazon, and some hardware stores (sold as drain cleaner, but ensure it is 100% pure NaOH with no additives). In other countries, check chemical supply shops or soap making suppliers. Always buy 97-99% pure NaOH with no added metals or fragrances.

Sodium hydroxide (NaOH) is used for solid bar soap. Potassium hydroxide (KOH) is used for liquid soap and cream soap. KOH produces a softer, more water-soluble soap paste. The SoapIndex calculator supports both; just switch the soap type and it adjusts the SAP values and lye amounts automatically. You can also use a dual-lye blend for specialty formulations.

Store lye in a tightly sealed, clearly labeled, moisture-proof container in a cool, dry location. Lye is hygroscopic — it absorbs water from the air and can clump or weaken over time if exposed to humidity. Keep it out of reach of children and pets, away from aluminum (which it reacts with), and separate from acids. A labeled HDPE container with a screw-top lid is ideal.

Seizing happens when the soap batter suddenly solidifies into a thick, unworkable mass. The most common cause is fragrance oils or essential oils that accelerate trace (cinnamon, clove, and vanilla-heavy fragrances are notorious). Other causes include soaping at too high a temperature or using a very fast-moving recipe. If it seizes, try spooning it into the mold (it will still be safe soap) or cook it hot-process style.

Soda ash is a harmless cosmetic issue caused by unsaponified lye on the surface reacting with carbon dioxide in the air. It does not affect the soap's performance or safety. Prevent it by forcing gel phase (insulate the mold with towels), covering the mold with plastic wrap, or spraying the top with 99% isopropyl alcohol immediately after pouring. You can steam it off or wash it off after unmolding.

Dreaded Orange Spots are caused by unsaponified oils oxidizing and going rancid. They usually appear weeks or months after making the soap and often have a rancid smell. Common causes include high superfat (above 8%), using old or already-rancid oils, high percentages of linoleic-rich oils (sunflower, grapeseed), and warm or humid storage. Prevent DOS by using fresh oils, keeping superfat at 5%, and storing soap in a cool, dry place.

Soft soap is usually caused by too much water (try a higher lye concentration like 33%), too little hard fat (add more coconut oil, palm, tallow, or lard), or not enough cure time. Let the bars cure for the full 4-6 weeks on a wire rack with good airflow. Adding 1 teaspoon of sodium lactate per pound of oils to the cooled lye solution also helps produce harder bars and faster unmolding.

Low lather is typically caused by too little coconut oil or castor oil in the recipe. Coconut oil provides big, fluffy bubbles; castor oil adds dense, stable lather. Try increasing coconut oil to 20-30% and adding 5% castor oil. Also, freshly made soap lathers less than fully cured soap — always wait the full 4-6 weeks before judging. Hard water can also reduce lather significantly.

It depends on the problem. A seized batch can be hot-processed (cook it in a slow cooker with a splash of water until it reaches a smooth, mashed-potato consistency). Soap that is lye-heavy (zap test positive) can be rebatched by grating, adding a bit more oil, and cooking. Soap that separated partially can sometimes be re-blended. However, if the batch is severely lye-heavy, rancid, or contaminated, it is safest to discard it.

Cracks usually mean the soap overheated in the mold. This is common with milk soaps, honey soaps, and recipes with a lot of sugar. Overheating causes the interior to expand and the surface to crack as it cools. Prevent it by soaping at lower temperatures, not insulating the mold (or even putting it in the fridge for the first 24 hours), and reducing sugar-containing additives.

Separation means the oils and lye solution did not fully emulsify. If you catch it early (within a few hours of pouring), you can scrape it back into a pot and re-blend with a stick blender until you reach trace again. If the soap has already partially hardened with pockets of oil or liquid lye, it is safest to rebatch it (grate and cook it down) or discard it, especially if there may be pockets of unreacted lye.

Save your recipe from the calculator, then open it from your dashboard and click "Publish." Published recipes appear in the public recipe library where other soapmakers can discover them. You can add a description, cover photo, difficulty level, and process notes. Published recipes include proper attribution to you as the creator.

Template recipes are pre-formulated starting points created by experienced soapmakers and the SoapIndex team. They cover common recipe types (basic beginner, Castile, bastille, high-lather, luxury bar, etc.) and are designed to be customized. Open any template in the calculator, adjust the oils or percentages to your liking, and save it as your own recipe.

Verification badges indicate that a recipe or ingredient has been reviewed for accuracy. For recipes, it means the formulation has been checked for safety (proper superfat, balanced metrics, no known issues). For ingredients, it means the SAP values and fatty acid profiles have been verified against published chemical references. Unverified content is community-contributed and should be double-checked.

Yes. Any published recipe can be opened in the calculator where you can modify it freely. When you save your modified version, it is linked back to the original recipe as a "remix," giving credit to the original creator. This is one of the best ways to learn formulation — start with a proven recipe and make small adjustments to see how they affect the quality metrics.

The recipe library features soap traditions and techniques from cultures worldwide, including Aleppo soap (Syria), Castile soap (Spain), African black soap, Nabulsi soap (Palestine), and many more. Recipes can be tagged with their tradition and origin, and you can browse by tradition to explore how different cultures approach soap making.

Yes. The soap calculator, ingredient library, recipe browser, safety guide, and glossary are all completely free to use with no ads. Creating an account is free and lets you save recipes, publish to the community, and access the AI assistant. SoapIndex is an independent project built for the soap making community.

The calculator uses published SAP values sourced from chemical references and industry databases for all 316+ ingredients. These values may vary slightly from other calculators because natural oils have inherent variability depending on harvest, region, and processing. The differences are small (typically less than 1%) and well within the safety margin provided by a 5% superfat. We recommend always running your recipe through at least one other calculator for critical batches.

Soapy is SoapIndex's built-in AI assistant, powered by GPT-4.1-mini. You can ask Soapy questions about soap making, ingredients, troubleshooting, or formulation advice, and it will respond with context-aware answers drawing on soap chemistry knowledge. Soapy is available from any page on SoapIndex and is a great way to get quick answers while you are working on a recipe.

If you cannot find an ingredient in the library, use the feedback widget at the bottom of any page to let us know. Include the ingredient name, and ideally the SAP values and fatty acid profile if you have them. We add new ingredients regularly and prioritize community requests. You can also reach us by email through the contact form.

Use the feedback widget available on every page — click the "Feedback" button in the bottom corner. You can report bugs, suggest features, or share general feedback. Include as much detail as possible (what you were doing, what you expected to happen, and what actually happened). Every report is read and helps improve SoapIndex for the entire community.