Making soap at home or in a small-scale business is a rewarding and creative craft that allows for total customization of ingredients, scents, and colors. The foundation of any great soap is its base oil or fat. With so many options available—from animal-derived fats like tallow and lard to plant-based oils like coconut, olive, and shea butter—it can be overwhelming to determine what is the best fat to make soap. This article dives deep into the properties of various fats and oils used in soapmaking, providing you with the knowledge needed to choose the ideal fat for your specific soap recipe.
Why Choosing the Right Fat for Soapmaking Matters
The fat or oil used in soapmaking directly determines the soap’s qualities, such as hardness, lather, moisturizing properties, cleansing ability, and curing time. Each fat contributes differently to the final bar, which means the right choice can make the difference between a soft, mushy bar and a firm, luxurious, long-lasting soap.
In cold process soapmaking, the oils react with lye (sodium hydroxide) in a process called saponification to form soap. Each oil has a unique saponification value, meaning it requires a specific amount of lye to fully convert the fat into soap. Using the wrong fat or miscalculating the lye amount can result in a failed batch that is either caustic or overly oily.
Animal Fats vs. Plant-Based Oils: The Ongoing Debate in Soapmaking
There are two broad categories of fats used in soapmaking: animal fats and plant-based oils. Each brings its own set of benefits and potential drawbacks.
Animal Fats
Animal fats, such as lard (from pork fat) and tallow (from beef fat), have been used for centuries in soapmaking. They are naturally saturated fats, making them excellent for producing hard bars of soap with a creamy lather.
- Lard is softer than tallow and produces a gentle, conditioning bar of soap ideal for sensitive skin.
- Tallow gives a harder bar with a luxurious, stable lather and is particularly favored in artisan soapmaking for its stable qualities and gentle cleansing action.
One benefit of animal fats is that they tend to be more economical. However, their source may be a concern for those following vegan lifestyles or for environmental and ethical reasons.
Plant-Based Oils
Plant-based oils offer a wide variety of options, each contributing unique properties to the final soap. These oils are typically categorized into hard oils and soft oils, referring to their consistency at room temperature and their impact on soap characteristics.
Hard Oils (Solid at Room Temperature)
- Coconut oil – Known for its excellent cleansing and lathering properties, but must be used in moderation to avoid over-drying the skin.
- Palm oil – Adds hardness to the bar and produces a creamy lather. Ethical concerns around deforestation have led many soapmakers to seek sustainable or alternative sources.
- Shea butter – Adds moisture and conditioning, but can make soap softer if used in larger percentages.
- Cocoa butter – Another luxury oil, adds hardness and a silky feel to soap but is expensive.
Soft Oils (Liquid at Room Temperature)
Understanding the Soapmaking Properties of Fats
When choosing fats for soapmaking, it’s essential to understand how each one contributes to the overall bar. Soap-making calculators and saponification charts help you determine the lye quantity needed, but knowing the properties each fat brings will guide your blend for the desired result.
Here is a comparison table of popular oils and their saponification values and properties:
| Fat/Oil | Lye Value (NaOH) | Insaponifiables (%) | Hardness | Lather | Conditioning | Cleansing |
|---|---|---|---|---|---|---|
| Coconut Oil (76%) | 0.190 | 15 | High | Excellent | Low | High |
| Olive Oil | 0.134 | 2 | Low | Low | High | Low |
| Palm Oil | 0.141 | 10 | High | Moderate | Moderate | Moderate |
| Shea Butter | 0.128 | 17 | Moderate | Moderate | Superior | Low |
| Lard | 0.138 | 10 | Moderate | Moderate | High | Moderate |
| Tallow | 0.140 | 10 | High | Moderate | Moderate | High |
| Castor Oil | 0.128 | 0 | Low | High | Moderate | Moderate |
Insaponifiables are components in oil or fat that do not react with lye but contribute other benefits such as vitamins and skin-friendly properties. Coconut oil has high insaponifiables and contributes to the conditioning effect in soap.
Coconut Oil: The Lathering Champion
Coconut oil is one of the most popular oils in soap-making due to its ability to create a firm bar and produce a rich, bubbly lather. A soap made entirely of coconut oil would be highly cleansing and drying, so it’s typically used in combination with other oils—usually around 20-30% of the total oil blend.
Benefits of Coconut Oil in Soap:
- Enhanced cleansing
- Produces a stable, long-lasting lather
- Hardens the bar quickly
- Great for oily skin due to its ability to remove excess oil
However, overuse of coconut oil can lead to dryness, especially for those with sensitive or dry skin. Soapmakers often balance it out with more conditioning oils like olive oil, shea butter, or avocado oil to avoid stripping natural oils from the skin.
Olive Oil: The Gentle Conditioning Base
Olive oil is often the base oil in Castile soap, a traditional soap often associated with gentle, natural cleansing. Typically green in color (when made from green olive oil), Castile soap is soft and moisturizing, making it ideal for sensitive skin.
Why Use Olive Oil?
Using 100% olive oil will result in a very soft soap that takes longer to set and longer to cure—up to 4-6 months. To improve the hardness and lather, many soapmakers blend olive oil with harder oils such as coconut or palm oil.
Palm Oil: Hardness and Stability
Palm oil is a common fat used in many commercial and artisan soap recipes due to its high stearic acid content, which contributes to a firm bar with a rich lather. However, due to the environmental impact of palm oil production, especially in Southeast Asia, sustainable palm oil or alternative fat sources are increasingly favored.
Alternatives to Palm Oil:
- Palm kernel oil
- Shea butter
- Rice bran oil
These alternatives can offer similar qualities without the environmental drawbacks.
Shea Butter: The Superfattering Powerhouse
Shea butter, derived from the nuts of the shea tree native to Africa, is a luxurious addition to soap. It’s not typically used as the primary fat but is often incorporated at 5-15% to add extreme conditioning and mildness.
Benefits of Shea Butter in Soap:
- Makes the bar extra moisturizing
- Adds a creamy texture and stability to the bar
- Naturally rich in vitamins A, E, and F
Because of its high cost, it is typically used sparingly.
Lard and Tallow: Classic, Functional Oils
One of the oldest fats used in soapmaking, lard (from pigs) and tallow (from cows or sheep) were the oils that built early soapmaking industries in Europe and America.
Why Use Lard or Tallow?
- Very affordable if sourced locally
- Produces a very hard bar with a creamy, long-lasting lather
- Extremely conditioning and mild
They are often used in traditional castile or homemade soaps but can present sourcing and ethical concerns for vegan soapmakers.
Blending Fats for Optimal Results
Most soapmakers create a blend of several fats to achieve a well-balanced bar of soap. The key parameters to consider when blending oils are:
- Hardness – The firmness and durability of the bar
- Lather – The amount, creaminess, and duration of bubbles
- Conditioning – The soap’s moisturizing effect
- Cleansing power – How effectively the soap removes oils
A common beginner’s cold process recipe might include:
- Coconut oil (25%) – For lather and hardness
- Olive oil (50%) – For conditioning
- Shea butter (10%) – For extra moisturizing
- Palm oil (15%) – For additional hardness and lather
By using a lye calculator and monitoring how each oil contributes to the total mix, soapmakers can adjust blends to match their needs.
Fatty Acid Composition and Its Impact on Soap Quality
Each oil contains different fatty acids. Understanding these components is key to grasping the saponification process and predicting soap quality.
Key Fatty Acids and Their Effects:
Balancing these fatty acids ensures a bar that cleans effectively without being harsh or overly conditioning without lacking lather.
Eco-Friendly and Ethical Considerations in Choosing a Fat
Environmental and ethical concerns are increasingly influencing choices in soapmaking. Factors to consider when selecting a base fat include:
- Sustainability of the oil source
- Carbon footprint of oil transportation
- Animal welfare, especially for animal-sourced fats
- Impact on local and global ecosystems
As such, many eco-conscious soapmakers prefer:
Additionally, vegan-certified labels and cruelty-free production practices are now major selling points for natural soap brands.
Conclusion: What Is the Best Fat to Make Soap?
There is no one-size-fits-all answer to the question: what is the best fat to make soap. The optimal choice depends on:
- Skin type and needs (dry, oily, sensitive)
- Desired lather (bubbly, creamy, soft)
- Soap hardness and longevity
- Ethical considerations (vegan, eco-friendly, sustainable sourcing)
For gentle, conditioning skincare soap, a blend of olive oil with shea butter and a small percentage of coconut oil makes a luxurious bar. For maximum lather and cleansing, higher amounts of coconut oil and a stabilizing agent like tallow or palm oil produces a more bubbly and firm soap.
Regardless of your choice, the key to successful soapmaking is understanding each fat’s contribution and balancing them to suit your specific recipe goals.
Whether you’re a beginner or a seasoned soaper, learning what is the best fat to make soap for your desired outcome ensures you create a bar that not only cleanses but nourishes and delights the skin.
Why is choosing the right fat important in soapmaking?
Selecting the appropriate fat or oil is crucial in soapmaking because it determines the soap’s hardness, lathering ability, moisturizing properties, and overall cleansing effectiveness. Different fats contribute distinct qualities to the final product—some provide a rich lather, while others add conditioning or stability. Using the wrong fat can result in a soft, oily, or overly drying soap that doesn’t perform well or may irritate the skin.
The chemical composition of each fat, particularly its fatty acid profile, directly influences the characteristics of the soap. For example, oils high in lauric acid, such as coconut oil, produce a hard bar with abundant lather, while oils like olive oil offer a softer bar that is gentle and moisturizing. Understanding these properties helps soapmakers craft a product that balances cleansing, conditioning, and durability, tailored to specific skin types and desired outcomes.
What are the best oils for making a moisturizing soap?
Oils that are high in oleic acid and low in saturated fats are ideal for creating moisturizing soaps. Olive oil is one of the most popular choices for this purpose due to its gentle and skin-nourishing properties. It produces a conditioning bar that is especially suitable for sensitive or dry skin. Other oils like avocado, almond, and sunflower also provide excellent moisturizing qualities and are often incorporated into formulations to enhance skin benefits.
In addition to their fatty acid content, these oils often contain natural antioxidants such as vitamin E, which help protect and repair the skin. However, because oils like olive oil can produce a softer bar that takes longer to cure, they are often blended with harder oils such as coconut or palm oil to improve bar firmness and longevity. This combination allows soapmakers to achieve the right balance between moisture and durability in the final product.
Which fats are best for creating a hard, long-lasting bar of soap?
Fats that are high in saturated fatty acids, such as coconut oil and palm oil, are best for producing a hard, durable bar of soap. Coconut oil, in particular, contributes significant hardness and generates a rich, bubbly lather that cleanses effectively. Palm oil adds stability and helps maintain a firm bar without drying the skin excessively. These oils are commonly used as the base in many commercial and homemade soaps to ensure a quality bar that lasts.
The use of animal fats such as lard or tallow can also help in making a hard bar, especially when rendered properly. These fats produce a long-lasting, conditioning soap when balanced with other oils. However, it’s important to consider sourcing and sustainability, especially when using palm oil or animal-based fats. The ideal approach is to blend high-saturation oils with more moisturizing oils to achieve the desired hardness and skin feel in the final bar.
Can I use cooking oils like vegetable or canola oil to make soap?
Yes, vegetable oils such as canola, soybean, and corn oil can be used to make soap, though they may yield different results compared to more traditional soapmaking oils. These oils are generally high in unsaturated fats, making them less ideal for producing a hard bar on their own. However, they are often used in combination with harder oils like coconut or palm oil to add conditioning and moderate cleansing properties without significantly altering the soap’s performance.
Canola oil, in particular, is a popular substitute among eco-conscious soapmakers due to its availability and affordability. It contributes mildness and a creamy lather when properly balanced in a formulation. Because these oils are often already hydrogenated or processed for culinary use, it’s important to verify that they are 100% pure with no additives before using them in soapmaking. Overall, while they are viable for soap, using them in blends yields better results than using them as a sole oil.
What is the role of lye in soapmaking and how does it affect the choice of fat?
Lye, or sodium hydroxide, is essential in soapmaking because it initiates the saponification process—the chemical reaction that turns fats into soap. The type of fat used affects how quickly and thoroughly this reaction occurs, as well as the properties of the resulting bar. Different oils have varying saponification values, which determine the exact amount of lye needed to fully convert the fat into soap without leaving excess lye, which could irritate the skin.
Choosing the right fat-lye ratio is critical to ensure that the soap is safe and effective. If too much lye is used, the soap can become overly alkaline and drying. Conversely, too little lye will leave the soap greasy and soft. Therefore, formulating a proper soap recipe involves calculating the appropriate lye amount based on the specific oils used. Understanding each fat’s saponification value allows soapmakers to create a balanced, skin-friendly product that cleanses well without being harsh.
Are animal fats a good option for soapmaking?
Animal fats, such as lard (from pork) and tallow (from beef), have been used for soapmaking for centuries and remain a viable option today. These fats produce a hard, long-lasting bar that lathers moderately and is often gentle on the skin. Tallow, in particular, is high in stearic acid, which contributes to a firm bar and stable lather, while lard provides a conditioning bar with a softer, creamier texture. These fats are often favored for their low cost and availability, especially for homemade soapmakers.
However, the use of animal fats requires careful rendering and purification to avoid impurities that can affect the final soap. Additionally, animal fats may not be suitable for those following vegan lifestyles or ethically conscious of animal sourcing. When used appropriately and in combination with other oils, animal fats can produce a high-quality bar that rivals those made with vegetable oils. Their sustainability and low environmental impact compared to some tropical oils also make them an attractive choice for eco-friendly soapmakers.
How can I blend different fats to create the perfect homemade soap?
Blending different fats allows soapmakers to balance the properties of each oil and tailor the final bar to specific preferences, such as hardness, lather, moisturization, and cleansing ability. A common approach is to use a primary oil (like coconut oil for lather and hardness), a secondary oil (such as olive oil for conditioning), and an oil with unique benefits (like castor oil for a rich, stable lather). Calculating the right combination involves understanding each oil’s fatty acid profile and how it contributes to the final soap.
Using a soap calculator is essential in determining the appropriate lye amount and ensuring that all oils are fully saponified for a mild, balanced bar. Adding a small amount of a luxury oil—such as jojoba, shea butter, or hemp oil—can further enhance moisturizing effects. It’s also important to consider how long the soap will need to cure, as some oil combinations may take longer to stabilize. Experimenting with blends over time helps soapmakers refine their recipes and create bars that meet both functional and aesthetic goals.