Marla Bosworth is the founder and owner of Back Porch Soap Company. She teaches classes, corporate events and experiences including candle making, soap making, organic skincare and perfumery.

March 03, 2017

How Much Fragrance for My Soap, Ice Trick and Other Cold Process Soapmaking Tips

Let's dive into some questions I recently received via email regarding cold process soap making. I hope that you'll find them helpful. Do you have other questions? Feel free to leave a comment and I may choose yours as my next blog post!

Q: Do carrier oils and butters lend any fragrance to the soap?

A: Not enough to notice. The only exception that I've experienced is cocoa butter added at 15-20 percent. It results in a light cocoa scent. I find that most of my clients and students want to add essential oils to create a beautifully scented soap. (I no longer use synthetic, fragrance oils. I stopped using them five years ago when I began to have breathing issues around them.)

Q: Is it true that sodium lactate will speed up the saponification process? What's the cure time when using sodium lactate? Is the cure time based on the weight of the soap?

A: Sodium lactate won't speed up saponification. However, it will result in a harder bar. I recommend that you try sodium lactate at 1% of your oil weight. If you've never seen it, it's clear and looks similar to glycerin.

To use, simply stir into cooled lye water (under 130F). However, you may not want to use sodium lactate if you are reducing the water content in your soap. It can cause overheating and cracking, which is a complete bummer.

Also, if you plan to use any liquid with a high sugar content (juices, milk, etc.), I suggest that you try a small batch first to see if the sodium lactate will behave in the batch. It can cause overheating in milk and juice soaps.

Cure time for the soap will be standard, which is around four weeks depending on your formula. For example, if you make a castille soap (100% olive oil), then your bars may take six to eight weeks to cure.

Try using ice in your lye water to keep fumes at a minimum
and to help cool your lye water temperature quickly.

Q: We used ice in our water during the soap making class with you in New York City. Can you remind me of the ratio of ice to water? Does it matter how much? Should I assume the weight of the ice and water should equal the water liquids needed for that particular batch?

A: Great question! And I'm sure many soapmakers will appreciate this tip. Let me first explain that I use ice for two reasons: 1.) to help the lye water temperature drop faster and 2.) to keep the sodium fumes at a minimum, which your lungs will thank you for years down the road.

The maximum amount of ice I recommend is 70% of your required liquid. You'll just replace 70% of your liquid weight with ice, then add the rest in water. Sometimes students ask if ice weighs the same as water, and the answer is yes. And yes, you're right in the assumption that you're going for the total amount of water liquids needed for the batch. The higher the ice amount, the stronger the probability that some of your lye may not dissolve completely. So start with a 50:50 ice to water ratio and you won't run into any problems with the lye not dissolving.

Q: How do I determine how much fragrance to add to my soap batch? When do I add it?

A: You can either add your fragrance to your oils before you begin soaping or you can add them at trace (thickening of the soap batter). I recommend adding them at trace, especially if you aren't sure how they are going to behave once added. Add a small amount at a time. If you see your soap thickening quickly or turning into tiny chunks, stop and quickly pour into your mold. This can happen with floral essential oils and especially fragrance oils, since the latter is made up of different chemical components. We never know how fragrance oils are going to behave. So if you are new to soap making, stick to essential oils like lavender, lemongrass, peppermint and rosemary in the beginning and you'll have very little chance of something going wrong because of them.

The usage rate for essential oils in cold process soap is 0.5 - 1 oz. per pound of oils used in your formula. This doesn't include water. Just your oil weight (olive, shea butter, coconut, etc.) Always weigh your fragrance and rest of ingredients for accuracy as opposed to using measuring cups.

To determine the amount of essential oils/fragrance, take the weight of your formula oils in pounds and multiple by .5 ounces. For example:

3 lb. oil
x .5 oz fragrance
1.5 oz.

Q: Do I have to line my molds?

A: If you are using wood or cardboard, yes. Line it with freezer paper or plastic wrap. If you are using plastic molds, I suggest you use plastic wrap inside the mold for an easy release. However, if you are using silicone molds, you can forgo the plastic wrap.

Q: Can you remind me what the temperature of the lye water and oils need to be before I combine them? Does it matter about the temperature of the essential oil?

Honestly, I don't even check temperatures anymore. I now teach my students to feel the sides of the lye/water and oil containers and get a feel for the temperature of under 120F or 130F. If you are new to soap making, you might want to use a thermometer in the beginning. Under 120F is ideal, but if you are at 130 or even higher your soap will be fine. My favorite temperature is room temp, which is right around 68 degrees in my house this winter.

Thanks for reading. If you're in the New York City area this month, be sure to check out my upcoming workshops!

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