Whether you're a seasoned soap maker or just starting out, the longevity of your bar soap is crucial. No one likes a soft, mushy soap that dissolves too quickly. In this guide, we'll explore nine effective methods to ensure your soap remains firm and lasts longer. From choosing the right oils to adding specific ingredients and adjusting curing times, these tips will help you craft a hard bar of soap that stands the test of time.
1. Use Hard Oils
One fundamental way to make your bar soap last longer is by incorporating hard oils into your recipe. Oils like coconut oil, palm oil, palm kernel oil, tallow, lard, and shea butter are rich in saturated fats, creating a solid structure in your soap. The increased solidity results in a longer-lasting bar that holds its shape.
2. Explore Oils’ Fatty Acid Profiles
Understanding the fatty acid profiles of the oils you use is essential for crafting a long-lasting bar of soap. Aim for a balanced ratio between saturated and unsaturated fats, typically between 54:46 and 51:49. This balance provides hardness while leaving room for moisturizing liquid oils.
3. Add Sodium Lactate
Enhance the hardness of your soap by adding sodium lactate to your recipe. Sodium lactate acts as a humectant, attracting and retaining moisture, ultimately increasing the soap's hardness. Incorporate it at around 1-3% of your oil weight for optimal results.
4. Add Beeswax or Other Waxes
Boost the firmness of your soap by adding beeswax or other waxes. A ratio of 1-2% in your recipe can significantly contribute to the hardness of the soap, giving it a sturdy and durable texture.
5. Use Water Reduction
The amount of water used in soap making affects its hardness. Reduce the water content in your recipe to create a harder soap. Decrease it by approximately 10%—for example, if your recipe calls for 5.75 ounces of water, use around 5.2 ounces.
6. Add Salt
Introduce salt to your soap recipe to enhance hardness. Whether it's sea salt, Himalayan salt, or table salt, adding around 1 teaspoon per pound of oils can contribute to a firmer soap. Mix the salt into cooled lye water for optimal results.
7. Add Stearic Acid
Incorporate a small amount of stearic acid to help harden your soap. As a vegetable-derived thickening agent, use stearic acid at a ratio of 0.5% of the total oils in your soap recipe.
8. Extend the Cure Time
Patience is key in soap making. Allowing your soap to cure for an extended period results in a harder final product. While most soaps require 4-6 weeks of curing, some high olive oil content soaps, like bastille or castile, may need up to a year for optimal hardness.
9. Use a Well Draining Soap
Proper drying is essential for a longer-lasting bar of soap. Handmade soap dissolves quickly if left in water for too long. Ensure your soap dries thoroughly between uses, and consider using a soap saver or similar products to facilitate proper drainage.
Simple Hard Soap Recipe
This recipe creates a 1 lb batch of soap with a lye concentration of 37%. Follow these steps for a unique and accurate hard bar soap:
INGREDIENTS:- Distilled water: 2.5 oz / 71 g
- Lye (sodium hydroxide): 1.5 oz / 43 g
- Coconut oil 76 (30%): 3.5 oz / 99 g
- Palm oil (30%): 3.5 oz / 99 g
- Shea butter (20%): 2 oz / 57 g
- Olive oil (15%): 1.5 oz / 43 g
- Castor oil: 0.5 oz / 14 g
- Beeswax: 0.5 oz / 14 g
- Sodium lactate: 1 teaspoon
- Himalayan salt: 1 teaspoon
- Cedarwood essential oil: 0.5 oz / 15 g
EQUIPMENT:- Gloves
- Goggles
- Heat-resistant container (plastic or stainless steel)
- Small plastic cup (for lye)
- Digital kitchen scale
- Stick blender / immersion blender
- Medium-sized heat-resistant container (plastic or stainless steel)
- Silicone soap mold or upcycled mold (e.g., empty yogurt cups or plastic food containers)
- Small plastic spoon
- Silicone spatula
INSTRUCTIONS:- Gear Up for Safety:
- Ensure you wear gloves, goggles, a face mask, and long sleeves throughout the entire soap-making process.
- Soap in a well-ventilated area, and keep kids and pets away. Stainless steel appliances are also important as lye can react with some metals like aluminum.
- Prepare Lye Solution:
- Measure lye into a small plastic cup.
- Measure water into a heat-resistant container.
- Slowly and carefully pour lye into water while stirring continuously. Avoid inhaling fumes.
- Set aside to cool. Sodium lactate will need to be added to the cooled lye solution.
- Melt Oils:
- Measure coconut oil, palm oil, shea butter, and beeswax into a heat-resistant container.
- Melt in the microwave (for plastic containers only), over the stove, or in a water bath.
- Once fully melted, remove from heat.
- Add olive oil and castor oil. Stir well.
- Combine Lye Solution and Oils:
- Wait until the lye solution and melted oils are cooled to slightly above room temperature.
- Carefully pour the lye water solution into the base oils. Essential oils should be added after you have emulsified your soap batter.
- Blend and Thicken:
- Use a stick blender on 10-second bursts until the soap batter starts to thicken.
- Continue stirring with a spatula until the batter reaches a thin pudding stage.
- Mold and Cure:
- Pour the soap batter into the mold.
- Set aside in a safe spot for 48 hours.
- Unmold and cure for 4 weeks.
- Store for Longevity:
- Store the soap in a small cardboard box away from sunlight and humidity for up to 12 months.
- Enjoy Your Long-Lasting Soap!
Mastering the art of making long-lasting bar soap requires a combination of quality ingredients, careful formulation, and patience during the curing process. By following these tips and experimenting with different recipes, you can create bars of soap that stand the test of time.
