Beginner's Guide to Soapmaking: Cold Process
If you want to customize soap down to the last ingredient, cold process is a great option. You get to choose the oils, colorants, scents, and more. Once you find your perfect recipe you can start getting creative with the designs.
Cold process soap is made by combining Oils and Sodium Hydroxide Lye. That causes a chemical reaction called saponification. Melt and pour soap has already gone through that process – learn more about it in the Beginner's Guide to Melt and Pour.
Below you’ll find cold process terms, safety tips, and a list of the equipment you need to get started.
Trace: This is the point when the oils and lye water are emulsified. At thin trace, there will be no streaks of oil and the soap will be the consistency of thin cake batter. As the soap sits, it will continue to thicken to medium and thick trace.
Gel phase: During gel phase, soap gets as hot as 180°F and develops a gelatinous appearance. Gelled soap has a brighter color and a slightly shiny appearance. It can also be unmolded more quickly. Some makers force their soap through gel phase with blankets and heating pads. However, gel phase isn’t required – it’s personal preference. It only affects the look of the bars, not the quality. Ungelled soap has a more matte appearance. You can prevent gel phase by putting soap in the freezer for 24 hours.
Curing: Technically, cold process soap is safe to use after a few days. However, we recommend letting the soap cure for 4-6 weeks in a cool, dry place with good airflow. Excess water will evaporate, which creates harder and milder bars that last longer in the shower. It’s definitely worth the wait.
Lye Calculator: This tool makes formulating cold process recipes easy. All you have to do is enter the oil weight or percentage and the Lye Calculator will give you the lye and liquid amount you need for your recipe. It also calculates the superfat level. Click here to learn about Using the Bramble Berry Lye Calculator.
Soda ash: This creates an uneven, white, ashy film on soap. It forms when unsaponified lye reacts with naturally-occurring carbon dioxide in the air. It doesn’t affect the quality and the soap is safe to use. However, it can obscure more intricate designs or make the bars feel crumbly. You can prevent it with a few tricks, including a 10% water discount and gel phase.
Sodium Hydroxide Lye is a highly corrosive product. It’s safe to use as long as it’s handled properly. Make sure there are no kids, pets, or other distractions in the room when you’re making soap and always do so in a well-ventilated area. You’ll need the following items to work with lye.
Nitrile Gloves: Rubber dish gloves that go almost to the elbow work great, but they can be bulky. Thinner nitrile or latex gloves provide protection without the bulk. Whatever you choose, they should be paired with long sleeves.
Soap Making Goggles: Alkali burns are extremely dangerous for your eyes. Your safety goggles should protect them from all sides, so regular glasses aren’t sufficient protection. If you wear glasses, make sure to get goggles that fit over them (like these Soap Making Goggles.)
Long sleeves, pants, and close-toed shoes: Protect yourself from unexpected splashes by covering any exposed skin.
Face mask: This is an optional step. If you’re sensitive to lye fumes or if you’re making large batches, you can wear a dust mask.
Any equipment used for soapmaking should be exclusive – don’t use it for food. Lye and fragrance can get stuck in cracks, even with thorough washing. We also recommend hand washing instead of using the dishwasher.
Containers We recommend heat-safe glass, plastic, or stainless steel bowls. Don’t use aluminum – it can react with the lye and create toxic fumes.
Stick/Immersion Blender Using a whisk or stand mixer can take hours. Stick blenders emulsify the soap in just a minute or two, so it’s worth the investment.
Silicone Spatulas and Spoons Use these to scrape every last bit of soap out of your container and into the mold. They’re also great for smoothing the top or creating texture.
Molds: There are plenty of options to choose from:
- Silicone: These molds are easy to use, unmold, and clean. They’re a great option for beginner and advanced crafters.
- Wood These are great for large batches and they make it easy to force gel phase. They need to be lined with freezer paper or a silicone liner.
- Plastic: You can use these for cold process, but they do require a few extra steps. We recommend a recipe with lots of hard oils and Sodium Lactate to help the bars come out cleanly and quickly.
A basic recipe:
30% Palm Oil
30% Coconut Oil
30% Olive Oil
10% Sweet Almond Oil
STEP ONE: Suit up in safety gear (goggles, gloves) and make sure all kids and pets are not in the general area. Measure out the lye and water amounts. Slowly and carefully add the lye to the water. Stir until the water turns clear again and set aside. Do not breathe the lye fumes.
STEP TWO: Melt (when necessary), measure and combine your oils (often referred to as ‘Fixed Oils‘).
STEP THREE: Once the oils and the lye water have cooled to below 130 degrees (and ideally are within 10 degrees of each other), carefully pour the lye water into the fixed oils. Pour the lye water down the shaft of the blender to avoid air bubbles.
STEP FOUR: “Burp” the stick blender by tapping on the base of the container to release any additional air bubbles. Pulse the stick blender to mix the oils and the lye water initially, then hold the mechanism at continuous blending until the soap reaches trace. Make sure your stick blender is fully submerged in the soap before turning it on, lest you end up with fresh soap batter all over your kitchen!
STEP FIVE: Once the soap has reached trace pour the soap into your mold. Tamp the mold on your work surface to release any air bubbles. Note: Trace is the time that you’ll add any color or fragrance additives. Always hand stir them in and start with the color before the fragrance oil.
STEP SIX: Allow the soap to stay in the mold for 24-48 hours. Unmold, cut, and cure for 4-6 weeks.