Hot Process Crockpot Soap

Hot process soap making in a crockpot is the perfect entry point for soap makers seeking faster results without the curing time of cold process soap. This beginner-friendly method produces finished bars in hours rather than weeks, making it ideal for those who want to see immediate results. The heat accelerates saponification, creating a rustic, textured bar that's ready to use within 24-48 hours.

Ingredients

Oils & Butters

• 20.0 oz (567g) coconut oil
• 15.0 oz (425g) palm oil
• 10.0 oz (284g) olive oil
• 5.0 oz (142g) castor oil

Lye Solution

• 5.1 oz (145g) sodium hydroxide (food-grade)
• 12.0 oz (340g) distilled water

Additives (Optional)

• 1.0 tbsp (15ml) dried lavender buds
• 0.5 oz (14g) lavender essential oil
• Colorant (1 tsp mica or natural colorant)

Equipment Needed

• 5-6 quart crockpot (dedicated to soap making)
• Digital scale (accurate to 0.1 oz)
• Stainless steel or glass mixing bowls
• Stainless steel spoon or stick blender
• Rubber spatula
• Thermometer
• Safety goggles
• Rubber gloves
• Towels for insulation
• Soap molds or parchment-lined containers

Instructions

Step 1: Prepare Your Workspace

Set up your work area with all equipment within reach. Ensure proper ventilation by opening windows or working near an exhaust fan. Put on safety goggles and gloves before handling any materials. Have towels ready for spills and keep baking soda nearby to neutralize accidental lye splashes.

Step 2: Measure and Combine Oils

Using your digital scale, carefully measure coconut oil, palm oil, olive oil, and castor oil into a heat-safe bowl. You can gently warm the oils to approximately 120-140°F to help them blend together more smoothly, though this step is optional as the crockpot will heat them during the process.

Step 3: Prepare Lye Solution

In a separate glass or stainless steel container, carefully measure distilled water. Slowly add sodium hydroxide to the water (never add water to lye), stirring gently with a stainless steel spoon. The mixture will become extremely hot. Allow it to cool to 120-140°F before proceeding. This typically takes 15-20 minutes.

Step 4: Add Oils to Crockpot

Pour your measured oils into the crockpot and turn it to low heat. If you haven't pre-warmed the oils, the crockpot will gradually warm them. You want the oils to reach approximately 120-140°F before adding the lye solution. This should take about 30-45 minutes depending on your crockpot.

Step 5: Mix Lye Solution with Oils

Once both lye solution and oils reach similar temperatures, slowly pour the cooled lye solution into the oils while stirring constantly. Stir for 3-5 minutes until the mixture becomes slightly thicker and lighter in color. This phase is called "light trace."

Step 6: Start the Crockpot Cook

Turn the crockpot to high and cook on low-to-medium setting. Do not cover it completely; leave the lid slightly ajar or place it on at-an-angle to allow some steam to escape. Stir occasionally (every 15-20 minutes) to ensure even cooking. The soap will go through various stages: grainy, separated-looking, then smooth and creamy.

Step 7: Watch for Completion

Over 30-60 minutes, the soap will change appearance as it cooks. You'll notice it becoming creamy and smooth, resembling mashed potatoes. This is called "gel phase" in hot process. Some batches reach a point where the soap looks fully saponified (smooth and creamy). Use a small amount on your hand (rinsed immediately) to test for zap—you should feel no bite or sting if soap is done.

Step 8: Add Fragrance and Colorants

Once the soap appears fully cooked and the zap test is negative, turn off the crockpot and let it cool for 3-5 minutes. Add essential oils or fragrance (if using) and colorants, stirring thoroughly. Add any botanical additives like dried lavender at this point and fold them in gently.

Step 9: Mold Your Soap

Pour the hot soap into your prepared molds or a parchment-lined container. The soap will be warm and pliable. You can press dried botanicals into the top if desired. Allow it to cool to room temperature, approximately 4-6 hours.

Step 10: Cure and Cut

Once cooled, remove the soap from molds. If molded in a block, cut into bars with a knife or soap cutter. Unlike cold process soap, hot process bars can be used immediately after cooling, though waiting 2-3 days allows them to harden and cure slightly. Store in a cool, dry place.

Tips for Success

• Temperature Control: The most critical factor in hot process soap is maintaining consistent, moderate heat. Too high will cause acceleration; too low will extend cooking time unnecessarily.
• Avoid Over-Stirring: While you should stir occasionally, excessive stirring can introduce air bubbles into your final soap. Stir just enough to ensure even cooking.
• Exact Measurements Matter: Hot process soap requires precise calculations. Use a reliable lye calculator if adjusting oil ratios. Even small deviations can affect soap quality.
• Invest in a Good Thermometer: An accurate thermometer prevents overheating and helps you understand your batch temperatures for future improvements.
• Keep a Log: Document your batch, oil amounts, temperatures, and timing. This helps you replicate successful batches and troubleshoot problems.
• Use a Dedicated Crockpot: Never use the same crockpot for food after using it for soap making. Label it clearly for soap use only.

Variations

• Moisturizing Version: Replace 5 oz castor oil with 5 oz jojoba oil for extra skin conditioning.
• Essential Oil Blend: Combine lavender (0.3 oz) with peppermint (0.2 oz) for an energizing morning soap.
• Herbal Infusion: Infuse oils with dried herbs like chamomile or rose petals before making soap for natural color.

Cost Breakdown

Estimated Cost per Bar: $0.76-$0.85

Related Recipes

• Fluid Hot Process Soap Recipe
• Marbled Clay Hot Process Soap
• Melt and Pour Lavender Soap

Storage Tips: Keep your finished soap bars in a cool, dry place away from direct sunlight. Use a soap dish that allows water to drain between uses to extend the life of each bar.